Plants that cause rashes

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7 plants that will make you sting, itch and blister

Marcus Schneck | [email protected]

Seven plants that will make you sting, itch and blister

Many plants cause skin irritation in humans. Different people react to the toxins in those plants differently and at different times in their lives.

Rash-, blister- and pain-causing toxins in many wild plants are everywhere in Pennsylvania, waiting for the slightest contact with some unsuspecting human. Depending upon your susceptibility, your reaction to some of them can range from mild to severe and requiring medical attention.

Here are seven common toxic plants that can give you a really bad day.

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Leaves of three, let it be

The trademark “leaves of three” makes poison ivy one of the easiest rash-makers to identify. It’s called trifoliate leaves, which means three leaves sprout at the same point on the stem. Poison ivy can grow as a vine, low shrub or ground cover. Poison ivy bears its fruit as clusters of greenish-white drupes, which are fleshy fruits each with a hard stone enclosing a seed inside.

The toxin, urushiol oil, is in the sap of the plant. Touching the plant can cause skin irritation, rashes and blisters.

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Close relative of poison ivy

Like its cousin, poison oak carries it leaves in trifoliate patterns on the stem. However, the leaves of the poison oak look like hairy oak leaves. Poison oak also can grow as a vine or shrub, and also bears its fruit as clusters of greenish-white drupes.

The same toxin, urushiol oil, as in poison ivy, causes the skin irritation, rashes and blisters from poison oak contact.

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Poison sumac

Growing as a tall shrub or small tree to a height of 6-30 feet, poison sumac carries the same urushiol oil as poison ivy and poison oak, but in higher concentrations. Some botanists rate poison sumac as the most toxic plant in North America.

Skin reaction to poison sumac includes painful swellings and eruptions, but if the smoke from burning sumac leaves is inhaled the result can be a life-threatening pulmonary edema, whereby fluid enters the lungs.

Poison sumac normally grows in wet areas.

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Giant hogweed

An invader from Asia, giant hogweed was introduced to the U.S. in the early 20th century and is now growing throughout the northeastern and mid-Atlantic U.S. It’s a giant member of the carrot family, growing as tall as 14 feet or more, with hollow stems 2-4 inches in diameter and large compound leaves as much as five feet wide. The tiny white flowers grow in clusters similar to the flowerheads of Queen Anne’s lace, but much larger.

The sap of giant hogweed, in combination with moisture and sunlight, can cause severe skin and eye irritation, painful blistering, permanent scarring and blindness.

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Wild parsnip

Also known as the poison parsnip, the wild parsnip is an aggressively invasive, non-native that has taken hold throughout the eastern U.S. It tends to colonize disturbed sites quickly. It grows 2-5 feet tall with tooth-edged basal leaves and small yellow flowers that grow in cluster similar to those of the Queen Anne’s lace.

Chemicals in the sap contains photosensitizing chemical compounds that are activated by ultraviolet radiation in sunlight. Exposure produces burnlike blisters.

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Stinging nettle

Native to Europe and Asia, stinging nettle found its way to North America and now grows coast to coast. It generally grows in highly invasive patches of single-stem plants 3-4 feet tall.

The stinging nettle is covered in small hairs. When touched those hairs “sting” with a nasty blend of histamine, serotonin, acetylcholine and formic acid. Skin reaction of localized pain, reddish swelling, itching and numbness generally last for a few hours maximum before resolving on their own.

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Wood nettle

Also known as Canada nettle, the low-standing wood nettle grows in open woods with moist soils, along streams and in drainages. It often grows into small clumps. Each plant has both stinging and non-stinging hairs on the foliage and the stems. It has small, whitish green flowers spring to early fall.

Contact with the stinging hairs will produce a painful burning sensation, following by rash and blistering, which can last for several days.

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More scary stuff

For another look at additional scariness lurking in the Pennsylvania outdoors, check out this slide show on wildlife-borne diseases in Pennsylvania.

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Plants that can make you itch

For most, knowledge of hazardous plants is limited to the phrase, “leaves of three, leave them be.” However, despite widespread awareness of a few common culprits, many casual outdoor enthusiasts may find themselves with an itchy souvenir following an encounter with a flower or shrub.

While poison ivy is the most common cause of contact dermatitis in the United States, a host of other common plants are capable of producing skin reactions. (Learn more about poison ivy, oak, and sumac)

Your backyard can be home to a variety of potentially hazardous plants. The following homegrown crops have been known to cause skin reactions:

  • Strawberry

  • Garlic

  • Tomato

  • Comfrey

  • Borage

  • Rose hips

  • Hot peppers

  • Tulip bulbs

  • Daffodil bulbs

  • Hyacinth bulbs

In addition, combined exposure to citrus fruit and sunlight should be avoided. Lemons, limes, clementines, oranges, and grapefruit all contain light-sensitizing chemicals that can cause a rash.

Avoid rash decisions — Don’t touch these plants!

Watch out! These plants can be found in all continental U.S. states:

Source: https://plants.usda.gov
*Spotted Water Hemlock can also be found in Alaska

Poison ivy prevention

Plastic bags are your friends
Use plastic or heavy shopping bags to pull plants from the soil, replacing the bags with the pulling of each plant. Plastic bags can also be used to cover arms for additional protection during the removal process.

Get to the root
Any lingering shoots or seedlings can be killed with white vinegar.

Cover up
Keep skin as covered as possible to avoid any potential contact. Wear long-sleeved shirts and pants.

Rinse, rinse, rinse
After removal or exposure to poison ivy, rinse any exposed skin with water immediately (avoid soap or harsh scrubbing), and wash clothes immediately.

Reference
“More Than Just Poison Ivy,” Dermatology World, June 2018.

Department of Environmental Conservation

Harmful Plants

When you are enjoying the outdoors, keep an eye out for these harmful plants that can cause rashes or skin irritation.

Poison ivy grows as a vine or small shrub that can trail along the ground or climb low plants, trees and poles. Each leaf has three glossy leaflets with smooth or toothed edges. Leaves are reddish in spring, green in summer, and yellow, orange, or red in fall. The plant may have greenish-white flowers and whitish-yellow berries. Every part of the plant contains an oil that inflames skin and results in painfully itchy blisters and rashes. Inhalation of smoke from burning leaves and vines is extremely hazardous. Poison ivy is often found growing in young woodlands, thickets, path edges, sand dunes, walls and roadways. More information on poison ivy.

This plant can appear as a woody shrub or small tree and grows up to 20 feet tall. Each leaf has clusters of 7-13 smooth-edged leaflets. Its leaves are orange in spring, green in summer, and yellow, orange, or red in fall. Poison sumac may have yellow-greenish flowers and whitish green fruits that hang in loose clusters, and can be found growing exclusively in very wet or flooded soils, usually in swamps and peat bogs. Every part of the plant contains an oil that inflames skin and results in painfully itchy blisters and rashes. Inhalation of smoke from burning leaves and vines is extremely hazardous. More information on poison sumac.

Giant Hogweed

Giant hogweed is very large, erect biennial or perennial. The plant has white flowers that appear in late summer, forming a large, flat-topped umbel up to 2.5 feet across. Hollow, rigid stems grow 2-4 inches in diameter, can be 8-14 feet tall, and have purple blotches and coarse hairs. Leaves can be 5 feet across and are lobed and deeply incised. Giant hogweed is usually found growing in rich, moist soils in open fields, wooded areas, tree lines, roadsides, ditches and along streams and rivers. Its sap contains a phototoxin that reacts with ultraviolet light to cause skin irritation ranging from a mild rash to severe blistering. More information on giant hogweed.

Cow Parsnip

This large plant grows 3-10 feet tall. Leaves are 12″-18″, rough and hairy, and divided into 3 segments with coarsely toothed leaflets and a broad wing at the base of each leaf stalk. Stems are rough, hairy, hollow and grooved. The plant has white or cream colored flowers that bloom in mid-summer. These flowers have 5 petals of different sizes and are arranged in broad, flat-topped clusters at the top of short stalks. Cow parsnip grows in a variety of habitats including woodlands, forest openings, grasslands, stream and river edges and along roadsides. Its sap contains a phototoxin that reacts with ultraviolet light to cause skin irritation ranging from a mild rash to severe blistering. More information on cow parsnip.

Wild Parsnip

Wild parsnip typically grows 2-5 feet tall and is found along roadsides, in pastures, and in fields. Its leaves are alternate, pinnately compound, branched, and have saw-toothed edges. Each leaf has 5-15 ovate to oblong leaflets with variable toothed edges and deep lobes. The plant’s stem is hollow and deeply grooved. Wild parsnip has small, 5-petaled, yellow flowers that are arranged in a flat-topped broad umbel 2-6 inches across and appear June-September. The flowers produce a round, smooth, straw-colored seed pod that is approximately 0.25 inches in size. Sap in all parts of the plant contains a phototoxin that reacts with ultraviolet light to cause skin irritation ranging from a mild rash to severe blistering. More information wild parsnip.

Stinging Nettle

Stinging nettle is a perennial, erect herb that can be identified by its stinging hairs, opposite heart-shaped leaves, and small greenish flowers. The stinging hairs on stems and leaves produce an intense burning and itching sensation that can last up to 30 minutes. The plant is most often found in forests or at the edges of woods and streams. More information on stinging nettle.

To keep yourself safe follow these tips:

  • Learn how to identify giant hogweed, wild parsnip, cow parsnip, poison ivy, poison sumac and stinging nettle.
  • Stay on the trails and away from areas known to have these plants.
  • Carefully wash any sap from clothing, equipment and pets.
  • If you think you have Giant Hogweed or Wild Parsnip on your property, or you see it in the community, report it to [email protected], 845-256-3111 or iMapInvasives (leaves DEC website). If emailing, please include photos if possible to help with identification.
  • Do not touch, cut, or collect parts of these plants, even for identification purposes.

Michigan noxious weed laws, though rarely enforced, define and regulate prohibited/restricted weeds

Some people define a weed as “a plant out of place.” For farmers, that plant competes for space, light, nutrients and moisture intended for the desired crop. With this in mind, every weed is undesirable and Michigan farmers spend millions of dollars annually on herbicides and seed technology to limit crop losses to weeds. In addition to efforts by agricultural industry to control weed competition, Michigan laws and regulations also attempt to regulate possession and sale of certain weed species. Even though these laws are not actively enforced due to scarcity of state funds, they are useful in providing awareness regarding weeds of special interest.Prohibited plant species identified under Act 451 of 1994, as amended, cannot be sold or grown in the state. The plants, fragments, seeds or a hybrid or genetically engineered variant are specifically prohibited. Better known selections from this list of 12 plants include Japanese knotweed and giant hogweed.Restricted plant species identified under the same act are those that may occur within the state and are generally considered nuisances or economically detrimental and are restricted. These include:

  • Flowering rush
  • Purple loosestrife
  • Eurasian watermilfoil
  • Phragmites (or common reed)
  • Curly leaf pondweed

Noxious weeds are identified in two categories under the Michigan Seed Law (Act 329 of 1965) and Regulations 715 (Under Act 329) Seed Law Implementation.Prohibited noxious weeds – seeds of these species are prohibited as contaminants in seed offered for sale:

  • Ragweed (Common and Giant)
  • Hoary alyssum
  • Mustards
  • Whitetop (aka hoary cress, peppergrass)
  • Plumeless thistle
  • Musk thistle
  • Spotted knapweed
  • Russian knapweed
  • Canada thistle
  • Bull thistle
  • Field bindweed
  • Hedge bindweed
  • Dodder
  • Yellow nutsedge
  • Wild carrot
  • Leafy spurge
  • Morningglory
  • Serrated tussock
  • Poison ivy
  • Horsenettle
  • Perennial sowthistle
  • Johnsongrass
  • Poison sumac
  • Puncturevine

Restricted noxious weed seeds – generally, the limit is one seed per 2,000 of agricultural seed offered for sale:

  • Velvetleaf
  • Wild onion
  • Wild garlic
  • Wild oat
  • Yellow rocket
  • Hairy alyssum
  • Indian mustard
  • Black mustard
  • Jimsonweed
  • Wild carrot
  • Buckhorn plantain
  • Wild radish
  • Curled dock
  • Giant foxtail
  • Charlock
  • Nightshades (bitter, silver leaf, eastern black, hairy)
  • Fanweed
  • Common Cocklebur

Archive for the dangerous plants tag

If you crush the stems or foliage of Virginia creeper, do not allow the juices to get on your skin.

My hobby-turned-profession has brought me up close and too personal with so many surprisingly dangerous plants that I’ve cultivated a downright awe of plant defenses. Each time I encounter another plant-based allergic reaction, skin irritation or chemical burn, my library and files swell with more books and articles. In pursuing one or another plant, I’ve come across cautions on so many other, common garden plants and said “Ah ha, so that’s what that other thing might have been!” so many times that I thought you would be interested in some of the discoveries too.

In listing these plants I do not intend to put an end to your enjoyment of any plant, but to point out where precautions might be in order. You’ll probably even find that to eliminate all potentially harmful plants from your garden or landscape would be very difficult, simply because so many plants have potential to cause harm. Better to learn safe ways to interact with plants—wear gloves, cover your arms and legs while pruning and gardening, wash well after being in the garden, and eat only known edible plants.

So knowledge is your best defense against plant defenses, and you should be prepared to learn more every time you add another plant to your garden or yard. Start by learning the several categories of dangerous plants: 1) those we shouldn’t allow to contact our bare skin, 2) those with pollen or other airborne elements that can cause distress if inhaled, and 3) plants we shouldn’t eat.

When you rub fennel (top), Queen Anne’s lace (above left), or rue (above right), on your skin, then stay out in the sun, a burn-like rash will appear. Growing any of these plants is good reason to cover your arms and legs when working in the garden.

Plants we shouldn’t allow to contact our bare skin

Of these three groups, we are most likely to come across those that irritate or inflame the skin on contact. That’s because we often expose bare skin when we garden and it’s not necessary to be allergic to react to many of them. The trouble with these plants are chemicals in their saps, thorns or prickles, or needle-like crystals contained in the cells which can seep out when the plant is bruised or cut.

Plants with irritant sap. These should be handled carefully if they must be cut. Avoid getting sap from cut stems or bruised leaves of any of the following on your skin:

• Buttercup (plants in the genus Ranunculus)
• Clematis
• Daffodil (Narcissus species)
• Daphne (D. mezereum)
• Euphorbias, such as gopher or mole plant (E. lathyris) and myrtle euphorbia (E. myrsinites)
• Marsh marigold (Caltha palustris)

If you think you may have contacted the sap, flush affected skin with water and wash it with a mild soap. Hydrocortisone cream may help relieve the irritation if it develops. Seek medical attention if the reaction is severe.

Phototoxic plants. Some plants have sap or oil that is not in itself irritating, but once on the skin and exposed to any sunlight, it can cause a chemical burn. The burn can be severe enough to raise blisters on sensitive skin, such as on the face or on a young child. The worst reactions happen after gardening on hot, sunny days since heat tends to bring the most oil to leaf surfaces and sun is the trigger to burning on the skin. If you have noticed burn-like marks or felt a burning sensation after a day’s gardening, you may have come into contact with:

• Angelica
• Bishop’s weed (Ammi majus)
• Celery (Apium graveolens)
• Chervil (Anthriscus cerefolium)
• Fennel (Foeniculum vulgare)
• Fig (Ficus species)
• Gas plant (Dictamnus albus)
• Hogweed (Heracleum species)
• Lime (Citrus species)
• Lovage (Levisticum officinale)
• Masterwort (Astrantia species)
• Parsley (Petroselinum crispum)
• Queen Anne’s lace (Daucus carota)
• Rue (Ruta graveolens)

Keep your arms covered and face averted when you cut down that ravenna grass each spring, since the edges of the blades are sharp enough to inflict serious damage.

Prickly plants. We tend to be careful around plants with visible thorns such as roses, firethorn and barberry, but here are some with tiny but irritating bristles or sharply serrated leaf edges that may not alarm us until we handle them without gloves or brush against them:

• Prickly pear cactus (Opuntia species)
• Hops (Humulus lupus)
• Ravenna grass (Erianthus ravennae)
• Redtwig dogwood (Cornus sanguinea)
• Stinging nettle (Urtica dioica)

Other plants that cause contact dermatitis in some people may do so because of the bristly nature of their leaves (see list below).

Tiny spines, as from cactus, can be removed by applying and removing adhesive tape or spreading and allowing white glue to dry on the skin, then peeling it off.

Plants containing needle-like crystals. Intense, painful itching can come from bruising or cutting these plants, because their cells contain needle-sharp crystals:

• Elephant’s ear (Colocasia esculenta)
• Dumb cane (Dieffenbachia species)
• Pothos (Epipremnum aureum)
• Heartleaf philodendron (Philodendron scandens)
• Virginia creeper and Boston ivy (Parthenocissus species)

Perhaps our best defense against dangerous plants such as poison ivy is to learn to identify them and steer clear of them!

Plants that cause allergic dermatitis. Some plants contain chemicals or have surface irritants which trigger allergic rashes in some, but not all people. Generally, reactions occur after the person becomes sensitized to the plant—it may take one or many contacts with a plant over many years to develop the sensitivity. The skin reacts most severely and most quickly where the most contact occurred, so that some parts of the body may “erupt” in a rash or blisters hours or days before another.

Poison ivy (Toxicodendron radicans) and its relatives cashew (Anacardium occidentale), smoke tree (Cotinus species), mango (Mangifera indica), and poison sumac (Toxicodendron vernix) are the most famous of these because they produce the most severe reaction among the widest range of people, but many other cultivated plants have been reported by doctors as causing irritated or inflamed skin. These include:

It’s hard to believe that something so universally loved as a magnolia can also be a dangerous plant. Yet some people are allergic to it, and develop a rash on contact with it.

• Artemisia (including the most notorious member of the genus, ragweed)
• Aster
• Balsam fir (Abies balsamea)
• Black walnut (Juglans nigra)
• Black-eyed Susan (Rudbeckia species)
• Blanket flower (Gaillardia species)
• Bleeding heart (Dicentra species)
• Castor bean (Ricinus communis)
• Daisy (Leucanthemum species)
• English ivy (Hedera helix)
• Feverfew (Matricaria species)
• Fleabane (Erigeron species)
• Garlic (Allium sativum)
• Gingko (Gingko biloba)
• Golden marguerite (Anthemis tinctoria)
• Helen’s flower (Helenium autumnale)
• Hyacinth (Hyacinthus species)
• Hydrangea
• Lady’s slipper (Cypripedium species)
• Magnolia
• Marigold (Tagetes species)
• Moses-in-a-boat (Rhoeo spathacea)
• Mullein (Verbascum species)
• Mum (Dendranthema/Chrysanthemum species)
• Oleander (Nerium oleander)
• Osage orange (Maclura pomifera)
• Pawpaw (Asimina triloba)
• Potato
• Primrose (Primula species)
• Purple heart (Tradescantia pallida)
• Tansy (Tanacetum vulgare)
• Tomato
• Trumpet vine (Campsis radicans)
• Tulip (Tulipa species)

Plants we shouldn’t inhale.

Plants with airborne pollen, such as ragweed, grasses and many conifers, can cause allergic respiratory distress. Those who suffer from pollen allergies should garden and landscape with plants visited by bees, moths, butterflies and hummingbirds, because such plants have heavy pollen which does not float but needs a lift to the next plant. Hosing down areas before working or playing outdoors can also be helpful, as wet pollen is less likely to waft into the air.

Plants we shouldn’t eat.

Although garden plants that, if eaten, can cause severe intestinal distress, nervous disorders and even death may get the most publicity of all dangerous plants, they are the most easy to live with—just don’t eat them! Never taste or eat any plant unless you are certain of its identity and safety.

Some plants are more dangerous than others, for various reasons. Tiny quantities of one species such as monkshood can cause great harm, while large quantities of another such as apple seeds or privet berries must be eaten to produce even mild side effects. In a few poisonous species such as anemone, calla, caladium, and Jack-in-the-pulpit, the symptoms are called “self-limiting,” meaning that it’s very tough to eat enough of the plant to cause life-threatening trouble since the plant is extremely distasteful or causes immediate burning and blistering on the tongue and lips.

The result of eating some toxic species may be gastrointestinal distress, which may be serious in young children and weakened adults, but may amount only to a tough lesson learned to other people. Some plant-produced toxins can cause circulatory or nervous system disorders as well and so are more serious. Some plants are toxic from top to roots, such as water hemlock. In others, poisons are concentrated enough to cause serious harm only in certain parts of the plant, even unlikely parts to eat, such as cherry and peach pits which contain cyanide.

Here are some of the most dangerous poisonous plants you may be growing, or which may be growing wild in your area, and the toxic parts:

• Adonis (Adonis species) – all parts
• Baneberry/Doll’s eyes (Actaea species) – berries and roots
• Buttercup (Ranunculus species) – sap
• Castor bean (Ricinus communis) – seeds
• Chinese lantern (Physalis species) – unripe fruits
• Daphne (Daphne mezereum) – all parts
• Datura, Jimsonweed, Angel’s trumpet, Devils’ trumpet (Datura and Brugmansia species) – all parts
• Fall crocus (Colchicum species) – all parts
• Flower tobacco (Nicotiana species) – all parts
• Foxglove (Digitalis species) – all parts
• Golden chain tree (Laburnum species) – all parts, toxins concentrated in seeds
• Hydrangea – flower buds
• Japanese andromeda (Pieris species) – leaves and nectar
• Lenten rose, Christmas rose (Helleborus species) – all parts
• Leucothoe – leaves and nectar
• Lily-of-the-valley (Convallaria majalis) – all parts, including water in the vase in which the flowers are held
• Monkshood (Aconitum species) – all parts
• Mountain laurel (Kalmia species) – leaves and nectar
• Oleander (Nerium oleander) – all parts, including water in the vase in which the flowers are held
• Pokeweed (Phytolacca americana) – leaves and roots
• Rhododendron and azalea (Rhododendron species) – leaves and nectar
• Star of Bethlehem (Ornithogalum species) – all parts
• Water hemlock (Cicuta species) – all parts
• Yew (Taxus species) – all parts except red portion of fruit

Janet Macunovich is a professional gardener and author of the books “Designing Your Gardens and Landscape” and “Caring for Perennials.” Read more from Janet on her website www.gardenatoz.com.

Jimsonweed – a poisonous plant that may be found in or around your horse pasture

The danger of poisonous plants depends on the plant’s prevalence, toxicity and palatability. Generally speaking, horses will avoid consuming most toxic plants if other forage is available. However, the risks of plant poisoning still exists if toxic plants are present. Good pasture management practices and honing your skills to be able to identify poisonous plants are important measures to prevent plant poisonings of your horse.

Jimsonweed (Datura stramonium) is a large summer annual (up to 5 feet tall) that typically emerges May through mid-June. Other common names include Jamestown weed, thorn apple, downy thornapple, devil’s trumpet, angel’s trumpet, mad apple and stinkwort.

Jimsonweed can be recognized by its distinctive tree -like shape, white to purple trumpet or funnel shaped flowers that are produced starting in June and prickly seed capsules. Photo Source: Tom Guthrie, Michigan State University Extension

Jimsonweed has long been known to be toxic all classes of livestock and to humans as well. Horses rarely consume Jimsonweed if other forage is available because of its foul odor and taste. All parts of the Jimsonweed plant are poisonous in which toxicity is caused by tropane alkaloids.

Symptoms of poisoning in horses may occur within minutes to several hours and may include: seeking water to drink, dilated pupils, agitation, increased heart rate, trembling, convulsions, coma and possibly death.

Methods for controlling Jimsonweed can range from mechanical to chemical. For chemical control options you may refer to the 2014 Michigan State University Extension Weed Control Guide for Field Crops, Table 4B – Weed Response to Herbicides in Established Forage Grasses. It is important to remember that if you choose to use a herbicide for control method, be sure to carefully read the label for grazing restrictions that may apply.

Additional resources:

Toxic plants of concern in pastures and hay for Michigan horses

MSU Weed Science

Poison Ivy, Poison Oak, and 7 Other Plants That Can Give You a Rash

Do you know which plants can give you a skin rash? It’s not just poison ivy.

Don’t touch! Both poison ivy and leadwort can give you a rash. Getty Images; Clare Gainey/Alamy

Being out in nature is good for body, mind, and spirit, but when you come home from your nature walk with an itchy rash — or develop one soon afterward — that innocent outdoor stroll can seem more stress-inducing than relaxing.

Chances are, that rash was caused by brushing against a common plant, such as poison ivy. But there are many other plants that can cause contact dermatitis — skin inflammation cause by an irritant or a substance that produces an allergic reaction — or shorter-lived burning or itching.

Learn what these irritating plants look like and where you might encounter them so you can avoid them on your next outdoor adventure.

1. Poison Ivy: The Best-Known Itchy Plant

Getty Images

Poison ivy is found across the United States. You can come into contact with it while hiking in the woods, but it grows virtually everywhere — along roadsides, on fences, in backyards. Poison ivy leaves grow in clusters of three on vines that can grow up into trees or trail along the ground. Every part of the plant contains the compound called urushiol, which causes poison ivy’s notorious rash — the vine, the roots, the leaves, the flowers, and the berries.

A poison ivy rash typically appears a few days after exposure, and can even take a week or two if this is your first time in contact with the plant. When it does, you’ll know it: You’ll see very red skin, swelling, and blisters, and you’ll feel a serious itch. A strong corticosteroid skin cream or ointment can help with the inflammation. Your doctor may prescribe other medication if the inflammation is severe, to either suppress your immune system or to help further reduce the reaction. Anti-itch topical creams may also help.

RELATED: How to Treat Poison Ivy and Reduce Discomfort

2. Poison Oak: Not Related to Oak Trees

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Poison oak is not related to oak trees, although its mature leaves somewhat resemble those of an English oak. Like poison ivy, poison oak is found throughout the United States, and it grows in forests as well as in dry spots, like sandy fields. Poison oak has deep green leaves that grow in clusters of three on a firm stem. Its yellow flowers are often described as hairy and its berries, fuzzy (unlike poison ivy’s smooth berries).

Also like poison ivy, every part of a poison oak plant contains urushiol in all seasons, meaning that any part of the plant can cause a rash if you come into contact.

Symptoms of and treatment for poison oak are the same as for poison ivy, and the severity of your reaction will depend on your individual sensitivity to the allergen.

3. Poison Sumac: Same Itch as Poison Ivy and Oak

John M Burnley/Getty Images

Poison sumac is another plant found throughout the United States that contains urushiol, the allergen in poison ivy and poison oak. It grows as a shrub or small tree in wet environments, such as near stream banks and ponds and in wetlands.

You can recognize poison sumac by its red stems that branch off the main trunk and its compound leaves, each with 7 to 13 green, smooth-edged leaflets. Poison sumac flowers are greenish-yellow and its berries gray and flattened.

Every part of the poison sumac plant can cause a rash if you come in contact with it.

4. Wood Nettle: Beware the Stinging Hairs

William Brooks/Alamy

Wood nettle is an herbaceous plant typically found in moist areas of woodlands. It tends to grow in large, dense patches, which can provide cover for wildlife. It is also a host plant for a number of insects and butterflies. It stands about 2 to 4 feet tall and has light- to medium-green stems covered with stiff, white hairs that sting when they’re rubbed against.

The leaves of the wood nettle plant are medium- to dark green, roughly oval-shaped, and serrated. Young leaves are densely covered with stinging hairs, while older leaves tend to have fewer of them, often located on the underside of the leaf. In summer the wood nettle blooms, with lacy strands of white flowers.

The sting from wood nettle usually subsides within an hour. You may also be able to reduce the irritation by pouring water over the irritated area when you notice the stinging, then washing the area with soap and water.

Some people collect wood nettle for food and sauté or steam it like a green vegetable.

5. Stinging Nettle: Close Relative of Wood Nettle

Alamy

Stinging nettle is the best-known member of the nettle family. It grows throughout the United States as well as in Europe, Asia, and North Africa. The plant tends to grow in dense patches near streams, along hiking trails, in ditches, and around farmland, often where the earth has been disturbed.

The stems of stinging nettle are singular, with few branches, and can grow 6 to 8 feet tall. The stems may be green or purple and may or may not have stinging hairs. The petioles (stem parts of the leaf) and undersides of the leaves also have stinging hairs.

The leaves of stinging nettle are longer than they are wide, and dark green, 2 to 4 inches long, with a tapered tip. Clusters of whitish flowers grow at the base of each pair of leaves along the stem.

Coming into contact with stinging nettle causes a sharp, painful sting, followed by a burning sensation and sometimes itching. The irritation can linger for several hours and cause hives near the site of contact which can last up to 24 hours.

Stinging nettle is sometimes gathered for food or to make into tea. It has long been a folk remedy for joint pain, eczema, arthritis, gout, and anemia. Cooking deactivates the stinging properties of stinging nettle.

6. Baby’s Breath: Irritating When Dried

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If you’ve ever gotten roses from a florist, chances are they were clustered with sprays of tiny white or pink flowers known as baby’s breath. You might also see baby’s breath in cultivated perennial gardens.

Baby’s breath generally isn’t an irritant while it’s still alive, but when it’s dried, it can irritate the eyes, nose, and sinuses, as well as the skin. It can additionally cause asthma in people who touch it frequently, such as floral industry employees.

The skin irritation caused by baby’s breath is usually minor and temporary.

People who have become sensitized to baby’s breath and are having asthma reactions ideally should stop handling it.

Interestingly, double-flower varieties of baby’s breath tend to cause fewer reactions than single-flower varieties, so if you’re planting it in your garden or have a choice when ordering a bouquet, go for the double-flower option.

7. Leadwort: Look but Don’t Touch

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Leadwort, also known as plumbago, is a mainly tropical shrub, but it can also be grown in the southern half of the United States. It is sometimes used by gardeners as a ground cover because of its tendency to spread underground and form a mat of plants.

Leadwort has shiny green leaves that turn red in autumn, and five-petal, medium-blue flowers that bloom in late spring or early summer and last until the first frost.

As lovely as this plant looks, resist any urge to touch it: Handling it can cause a skin irritation, redness, or blistering. Wear gloves when working with it in the garden.

8. Ragweed: Sneezing and Skin Rash

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Ragweed is best known for causing hay fever, or seasonal allergic rhinitis, in the fall. But it can also cause a rash in people who are allergic to ragweed pollen. The rash may appear as itchy red streaks on the skin or swollen eyelids.

A ragweed rash can develop after a person directly touches the plant pollen or is exposed to airborne pollen, making it difficult to avoid.

But if you have ragweed growing on or near your property, it may help your allergies to remove it.

Common ragweed has delicate, deeply lobed leaflets that are medium-green in color. The flowers — and sources of pollen — grow in “spikes” from the top of the plant and elongate over the summer.

Another type of ragweed, called giant ragweed, has similar flower spikes but very different leaves. The leaves at the bottom of the stalk have three or sometimes five lobes, while the leaves at the top of the plant are elliptical.

RELATED: 8 Tips for Fall Allergy Relief

9. Giant Hogweed: Invasive Plant, Serious Rash

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Giant hogweed is an invasive plant in Europe and North America and, according to the New York Department of Environmental Conservation, a “federally listed noxious weed” in the United States.

Contact with the sap of giant hogweed can cause serious skin and eye irritation, blistering, scarring, and even blindness if the sap gets in the eye. The skin rash may look like a second-degree burn and can leave you with long-lasting scars and sensitivity to sunlight.

Giant hogweed sap is phototoxic, which means it requires exposure to ultraviolet light to cause a reaction. If you touch giant hogweed — or think you might have — keep the exposed area away from sunlight for 48 hours, and wash it with soap and cold water as soon as possible. If you get sap in your eyes, rinse them with water and wear sunglasses. See a physician if you have a reaction.

You can recognize giant hogweed in part by its size: It can grow to 14 feet high or higher and has hollow, ridged stems 2 to 4 inches in diameter. Its deeply lobed, compound leaves can grow up to 5 feet across, and its white, umbrella-shaped flower heads, can be up to 2.5 feet across. The stems of giant hogweed are green with purple splotches and coarse, white hairs.

Beware of these poison ivy-like plants

By: health enews Staff

Most of us are probably familiar with the notorious poison ivy plant. It has three leaves, grows virtually anywhere and our parents have been warning us about it since we were kids.

Still, as the summer season unfolds and many of us plan trips to parks or maybe just a stroll through the local forest preserve, we may wonder – what else should we look out for?

Dr. Michael Jude Welsch, a dermatologist associated with Advocate Christ Medical Center in Oak Lawn, Ill., shares four common rashes or irritations he has seen from plants, beyond poison ivy: poison oak, poison sumac, stinging nettle and giant hogweed.

The reactions caused by these plants are called “contact dermatitis” because physical contact with these substances creates uncomfortable rashes. What is characteristic about these contact rashes is that they generally appear on a line where your body brushed against the plant.

It is important to remember that first contact with these allergens generally causes no symptoms. The body sensitizes to these substances and gets ready for the next contact. Once someone has an initial contact, each subsequent reaction gets worse.

1. Poison Oak

Contrary to what you may think, this rash doesn’t actually come from oak trees. It comes from the leaves or stems of the western poison oak plant, which looks like a leafy shrub and can grow up to six feet tall, and in some cases, grows like a climbing vine. The leaves usually have three separate leaflets, but there can be up to nine leaflets. Poison oak is found throughout the U.S. in forests and dry areas.

“Poison oak symptoms include extreme itching, a rash or red streaks and patches, blisters that contain and sometimes leak fluid and inflammation,” says Dr. Welsch.

2. Poison Sumac

Dr. Welsch says poison sumac symptoms are similar to those of poison oak and poison ivy, causing an itchy and blistering rash. However, unlike poison oak, this plant is typically found in wet environments.

3. Stinging Nettle

The name says it all. When encountering stinging nettle, Dr. Welsch says you may experience a piercing sting followed by irritation and a burning feeling around the affected area. That’s because the plant has sharp, stinging, tiny hairs that break easily and encompass the entire plant. Contact with this plant may cause red, itchy welts in varying shapes and sizes, for six to 12 hours.

Be careful to watch out for this plant along hiking trails.

Plants like giant hogweed cause rashes when the allergen on the skin is exposed to sunlight. These reactions are called “Phytophotodermatiti” or literally: plants, light, rash.

4. Giant Hogweed

Giant hogweed has stout, bright green stems that are frequently spotted with dark red and hollow red-spotted leaf stalks that produce sturdy bristles. Contact can be severe, causing painful blistering that may lead to permanent scarring. If exposed to eyes directly or indirectly, it causes irritation and may even lead to blindness.

Other phytophotodermatitis come from parsley, celery, carrots, and limes.

“I’ve seen a number of cases where the use of limes in drinks especially in the summer, have caused severe rashes on the hands and lips,” Dr. Welsch says. “So be careful when drinking that margarita or squeezing that lime into your favorite beer.”

Treatments

Dr. Welsch offers the following advice to anyone exposed to the plants and showing symptoms:

  • First, wash the assumed affected area with soap and water thoroughly and carefully change clothes they have been exposed.
  • Depending on the severity of the rash, it may go away by itself after a couple of weeks. This is often common for rashes like poison ivy, oak or sumac.
  • Over-the-counter aids may help relieve the itching and inflammation. Those options include hydrocortisone creams, ointments or a soaked compress, such as Domeboro. In cases of hives, over-the-counter antihistamines are recommended to reduce itchiness.
  • In severe cases, seek medical attention.

Irritating Plants

A cactus is pretty obvious in showing its thorny side. Other plants are more subtle, but no less ouchy. “Some plants are just very irritating to the skin,” says Rajani Katta, MD. “Some from the presence of thorns or needles, but other plants have sharp edges or hairs on them that can cause skin irritation.”

Katta, who is the director of the contact dermatitis clinic at the Baylor College of Medicine in Houston, says plants that cause skin abrasions and irritated skin may have these features:

Sharp-edged or pointed leaves. Plants such as agave or yucca have needle-sharp leaves, and getting too close can leave you with a cut or skin abrasion. Some decorative plants such as pampas grass look soft, but actually have razor-sharp edges that can easily slice skin. And holly plants, while pretty to look at, can deliver a sharp poke if you touch their leaves.

Thorns. No surprise here. Classic beauties such as rose bushes and bougainvillea – just two examples of thorny shrubs — are notoriously prickly.

Spines and glochids. One look at a barrel cactus and you know to keep your distance. But some types of cactus, like the prickly pear, are covered with very fine, hair-like, barbed thorns called glochids. Glochids can become embedded at the slightest touch and are hard to see to remove.

Stem and leaf hairs. These fine hairs can be found on the stems and leaves of plants such as borage, an herb sometimes used in cooking, and seemingly innocent flowering plants such as forget-me-nots and dogwood trees. Because they are harmless-looking, stem and leaf hairs can catch people by surprise and cause skin irritation.

Barely visible irritant fibers. Home gardeners may be surprised to find out that tulip bulbs can cause skin abrasions. “Because these fibers are so small, you don’t think of tulips as being dangerous in any way,” Katta says. But people who frequently handle tulips bulbs can get a condition called “tulip fingers,” caused by a combination of the irritating fibers and a certain chemical in the bulb.

Pollen Allergy

What Is a Pollen Allergy?

Pollen is one of the most common triggers of seasonal allergies. Many people know pollen allergy as “hay fever.” Experts usually refer to pollen allergy as “seasonal allergic rhinitis.”

Each spring, summer and fall, plants release tiny pollen grains to fertilize other plants of the same species. Most of the pollens that cause allergic reactions come from trees, weeds and grasses. These plants make small, light and dry pollen grains that travel by the wind.

Grasses are the most common cause of allergy. Ragweed is a main cause of weed allergies. Other common sources of weed pollen include sagebrush, pigweed, lamb’s quarters and tumbleweed. Certain species of trees, including birch, cedar and oak, also produce highly allergenic pollen.

Plants fertilized by insects, like roses and some flowering trees, like cherry and pear trees, usually do not cause allergic rhinitis.

What Is a Pollen Count?

A pollen count is how much pollen is in the air. This is often reported during pollen season on local weather forecasts. Sometimes the main types of pollen are also reported.

What Are the Symptoms of Pollen Allergy?

People with pollen allergies only have symptoms when the pollens they are allergic to are in the air. Symptoms include:

• Runny nose and mucus production

• Sneezing

• Itchy nose, eyes, ears and mouth

• Stuffy nose (nasal congestion)

• Red and watery eyes

• Swelling around the eyes

How Do Doctors Diagnose Pollen Allergy?

Doctors use two tests to diagnose a pollen allergy.

Skin Prick Test (SPT)
In prick/scratch testing, a nurse or doctor places a small drop of the possible allergen on your skin. Then the nurse will lightly prick or scratch the spot with a needle through the drop. If you are allergic to the substance, you will develop redness, swelling and itching at the test site within 20 minutes. You may also see a wheal. A wheal is a raised, round area that looks like a hive. Usually, the larger the wheal, the more likely you are to be allergic to the allergen.

A positive SPT to a particular pollen allergen does not necessarily mean that a person has an allergy. Health care providers must compare the skin test results with the time and place of a person’s symptoms to see if they match.

Specific IgE Blood Test
Blood tests are helpful when people have a skin condition or are taking medicines that interfere with skin testing. They may also be used in children who may not tolerate skin testing. Your doctor will take a blood sample and send it to a laboratory. The lab adds the allergen to your blood sample. Then they measure the amount of antibodies your blood produces to attack the allergens. This test is called Specific IgE (sIgE) Blood Testing. (This was previously and commonly referred to as RAST or ImmunoCAP testing.) As with skin testing, a positive blood test to an allergen does not necessarily mean that an allergen caused your symptoms.

How Can I Prevent an Allergic Reaction to Pollen?

There are actions you can take to reduce allergic reactions to pollen:

  • Limit your outdoor activities when pollen counts are high. This will lessen the amount of pollen allergen you inhale and reduce your symptoms.
  • Keep windows closed during pollen season and use central air conditioning with a CERTIFIED asthma & allergy friendly® filter attachment. This applies to your home and to any vehicle (car, bus, train, etc.).
  • Start taking allergy medicine before pollen season begins. Most allergy medicines work best when taken this way. This allows the medicine to prevent your body from releasing histamine and other chemicals that cause your symptoms.
  • Bathe and shampoo your hair daily before going to bed. This will remove pollen from your hair and skin and keep it off your bedding.
  • Wash bedding in hot, soapy water once a week.
  • Wear sunglasses and a hat. This will help keep pollen out of your eyes and off your hair.
  • Limit close contact with pets that spend a lot of time outdoors.
  • Change and wash clothes worn during outdoor activities.
  • Dry your clothes in a clothes dryer, not on an outdoor line.

Look for this mark to find products proven more suitable for people with asthma and allergies.
Find CERTIFIED asthma & allergy friendly® products on our Certification program website or download our app on the App Store or Google Play.

What Is the Treatment for Pollen Allergy?

Certain over-the-counter and prescription medicines may help reduce pollen allergy symptoms.

  • Antihistamines come in pill, liquid or nasal spray form. They can relieve sneezing and itching in the nose and eyes. They also reduce a runny nose and, to a lesser extent, nasal stuffiness.
  • Decongestants are available as pills, liquids, nasal sprays or drops. They help shrink the lining of the nasal passages and relieve nasal stuffiness. Use decongestant nose drops and sprays only on the short-term.
  • Nasal corticosteroids are a type of nasal spray. They reduce inflammation in the nose and block allergic reactions. They are the most effective medicine type for allergic rhinitis because they can reduce all symptoms, including nasal congestion. Nasal corticosteroids have few side effects.
  • Leukotriene receptor antagonists block the action of important chemical messengers (other than histamine) that are involved in allergic reactions.
  • Cromolyn sodium is a nasal spray that blocks the release of chemicals that cause allergy symptoms, including histamine and leukotrienes. This medicine has few side effects, but you must take it four times a day.

Many people with pollen allergy do not get complete relief from medications. This means they may be candidates for immunotherapy. Immunotherapy is a long-term treatment that can help prevent or reduce the severity of allergic reactions. It can change the course of allergic disease by modifying the body’s immune response to allergens.

Allergy Shots – Subcutaneous Immunotherapy (SCIT) has been around for more than 100 years and can provide long-lasting symptom relief. SCIT is a series of shots that have progressively larger amounts of allergen. An injection of the allergen goes into the fat under the skin. Over time, allergic symptoms generally improve. Many patients experience complete relief within one to three years of starting SCIT. Many people experience benefits for at least several years after the shots stop.

Sublingual Immunotherapy involves placing a tablet containing the allergen under the tongue for 1 to 2 minutes and then swallowing it. In 2014, the FDA approved three types of under-the-tongue tablets to treat grass and ragweed allergies. More are in development. You take SLIT tablets daily before and during grass or ragweed season. This treatment offers people with these allergies a potential alternative to allergy shots.

Discuss your allergy symptoms and your allergy treatment plan with your health care provider.

Medical Review October 2015.

Allergic to Weeds? You Can Still Go Outside

In his book, Allergy-Free Gardening, author Thomas Ogren uses a Plant Allergy Scale to rate plants from 1 (low) to high (10) for pollen and allergies. The book also provides many useful tips for reducing your exposure to allergens.

Many weeds are among the worst allergenic plants. Take Common Ragweed for example. One Common Ragweed plant can produce up to one billion pollen grains, and they have been tracked over 400 miles away! Other weeds that can cause allergy problems with their pollen include Pigweed, Bermudagrass, Annual Bluegrass, Dallisgrass, Dandelion, Dock, Lambsquarters, Nettle, Plantain, Ryegrass and Sagebrush, plus many others. Bottom line – control weeds in your lawn and garden and you can reduce your exposure to troublesome pollens.

Weeds are usually easiest to control in spring when they are small and actively growing. However, fall can also be a crucial time to control cool-season weeds in mild winter areas, especially in lawns. Hoeing, mulching and cultivating can help reduce weeds, but herbicides that prevent or kill weeds are often an easier, more efficient method of control, especially if weed pollen is a health concern. Mowing can reduce weeds in lawns temporarily, but unfortunately, they’ll regrow. Just one missed mowing can result in abundant pollen, especially with weedy grasses like Bermudagrass or Annual Bluegrass. A herbicide like Season Long Weed Control For Lawns is a more effective and longer-lasting solution.

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