Will anaphylaxis wake you up?

7 Surprising Triggers of Anaphylaxis

Peanuts and shellfish aren’t the only causes of anaphylaxis. Here are some more triggers you should be aware of.

Latex and red meat are among the lesser-known triggers for anaphylactoid reactions. iStock (2)

The best-known triggers for anaphylaxis, a severe allergic reaction, are foods like peanuts, tree nuts (such as walnuts), eggs, shellfish, and milk. (1)
But foods like these are responsible for just 6.7 percent of fatal cases of anaphylaxis, according to a study published in December 2014 in the Journal of Allergy and Clinical Immunology.
It may surprise many people to learn that drugs and blood products are the most common causes of anaphylaxis deaths, according to the 2014 report. These deaths usually occur when people are on an IV in a hospital, so avoiding these triggers on your own is difficult. (2)

Some other surprising causes of anaphylactic reactions include exercising, getting stung by an insect, or even having your period — though these are not nearly as likely to be fatal reactions.

What Is Anaphylaxis?

In anaphylaxis, your immune system reacts to a food or substance as if it’s a harmful invader and attempts to defend your body by releasing a flood of chemicals that cause allergy symptoms. It can be scary — and life-threatening.
“Anaphylaxis is an immune response gone wild,” explains Daniel J. Stone, MD, an internist at Cedars-Sinai Medical Group in Los Angeles.
Symptoms of anaphylaxis can include shortness of breath, wheezing, tightening of the throat, hives, facial or body swelling, stomach pain, and heart palpitations.

In especially severe cases, anaphylaxis can cause shock, a dangerous condition in which your blood pressure drops and your pulse weakens. (1)

The first line of treatment for an anaphylactic reaction is epinephrine, Dr. Stone says. If you have a history of serious allergies or anaphylaxis, you should carry an epinephrine auto-injector — a penlike device that delivers a single dose of the medication — and use it at the first sign of an episode.
“It buys you time to get to the emergency room,” says Scott H. Sicherer, MD, a pediatric allergist and immunologist at Mount Sinai Medical Center in New York City.
You may also want to wear a medical ID bracelet and carry a card identifying your allergy, Dr. Sicherer says. In an emergency, this information can be useful to first responders and doctors, especially if you’re unable to speak.
Still, the best defense against an anaphylactic reaction is to avoid whatever causes it. Here are some lesser-known potential causes of anaphylaxis.

1. Exercise Can Be a Cause, on Its Own or With Food, Pollen, or Medication

You may be running on the treadmill and suddenly experience extreme fatigue, warmth, flushing, wheezing, itching, hives, or facial swelling. These are symptoms of exercise-induced anaphylaxis, which also can be triggered by moderate activities such as brisk walking or vigorous yard work.
This form of anaphylaxis is estimated to make up 5 to 15 percent of all episodes, according to a study published in February 2011 in the journal Current Allergy and Asthma Reports. (3)
In some instances, exercise alone triggers anaphylaxis. In others, it’s exertion combined with a food eaten just before the workout. Symptoms can come on suddenly.
“A person can go jogging every day of the week and be fine,” then eat a certain food before jogging and have a reaction, Sicherer says.
Other potential triggers in combination with exercise can be pollen or medication, such as penicillin or aspirin.
To make diagnosis even more confusing, your response may not be consistent. A severe reaction may happen repeatedly or only sporadically, says Sicherer.

If you’ve experienced anaphylaxis while exercising, work out with a friend who can administer treatment and get help. If you feel symptoms coming on, take your epinephrine and seek medical help.

2. For Susceptible Women, Semen Is a Trigger

Sperm allergy, also called semen allergy, is a rare cause of anaphylaxis but can cause life-threatening symptoms in women who have it during or after intercourse with a man.

It’s more likely in women who have allergic asthma (asthma triggered by allergies) or atopic dermatitis (a skin disorder sometimes caused by allergens).
In some cases, the anaphylactic reaction occurs because the woman’s partner ate something or took a drug that she’s allergic to, which is then transferred through his semen. In other cases, it’s an allergy to seminal plasma protein, a natural component of semen.

After contact with semen, a woman may experience serious anaphylactic symptoms ranging from itching and hives to shortness of breath, throat swelling, wheezing, pelvic pain associated with uterine contractions, low blood pressure, or loss of consciousness.
To prevent this reaction, use a condom (but remember that latex can also trigger an allergic reaction), and ask your partner to avoid eating foods or using medications that you’re allergic to. (4,5)

3. Catamenial Anaphylaxis Is Linked to the Menstrual Cycle

Some women experience anaphylaxis just before or during their menstrual cycle. Known as catamenial, or cyclic, anaphylaxis, this rare disorder often goes unrecognized.
“Most patients, and even healthcare providers, aren’t aware of the association between anaphylaxis and the menstrual cycle,” says Cindy Salm Bauer, MD, an allergist and immunologist at Phoenix Children’s Hospital in Arizona.
In some cases, the culprit is a medication or food consumed around the time of menstruation.
At other times, though, no cause can be found, according to a study conducted by Dr. Bauer and colleagues and published in August 2013 in the journal Annals of Allergy, Asthma & Immunology.
The eight women followed in that study experienced hives, flushing, chest tightening, low blood pressure, light-headedness, unconsciousness, abdominal pain, diarrhea, facial swelling, throat constricting, wheezing, and difficulty swallowing.
For some women, the anaphylaxis didn’t recur when they were given a hormone called medroxyprogesterone, which regulates ovulation and menstruation. And one woman in the study found relief from symptoms after a salpingo-oophorectomy, a procedure in which the fallopian tubes and ovaries are removed. (6)
If you suspect you have catamenial anaphylaxis, you should be evaluated by an allergist, Bauer says. Your doctor’s questions may help uncover the link between anaphylaxis and your menstrual cycle.
“Sometimes, creating a diary of anaphylactic events and the menstrual cycle can clarify the association,” Bauer says.
You should also carry an epinephrine auto-injector.

4. Latex Is a Threat to Those Who Regularly Wear Latex Gloves

The more you’re exposed to this rubbery product, the more likely you are to develop an allergy to it, according to the Mayo Clinic.

So if you’re a healthcare worker, hairdresser, or housekeeper who wears latex gloves, you’re at a higher risk for latex allergy.
If you have any sensitivity to latex, avoid latex gloves. You can find latex-free gloves in drugstores or online.

If you have to wear latex, look for gloves that are powder-free, since they contain less latex protein — the substance that causes the allergic reaction. Wash your hands with soap and water after removing them.
If you receive medical or dental care, let healthcare workers know that you’re allergic to latex and ask that procedures be performed in a latex-free environment. (7)

5. Anaphylaxis From Eating Meat May Occur Hours After Eating

Meat from mammals — beef, pork, lamb, veal, venison, rabbit, and others — and sometimes poultry can cause symptoms of anaphylaxis hours after you eat it, making it difficult to draw a connection between the food and your allergy.
With most other allergies, “it’s unusual to have anaphylaxis hours after exposure,” Sicherer says.
But with this form of anaphylaxis, you may not experience symptoms until three to six hours later, he says. That’s because it takes time to digest the meat.
A bite from a tick called the lone star tick can cause this allergy. That’s because your immune system develops antibodies to alpha-gal, a sugar found in both the tick and red meat.
This form of anaphylaxis is more common in woodsy southeastern states where ticks thrive. Lone star ticks have been found from Texas to Iowa to New England. (8)

6. Insect Stings Are Among the Deadliest Animal Encounters

As many as 90 to 100 people in the United States die each year because of a severe allergic reaction to an insect sting, according to the Centers for Disease Control and Prevention. (9)
Bees, hornets, and wasps — including yellow jackets — and stinging ants are the insects whose stings are most likely to cause a severe anaphylactic reaction.

If you’ve ever had an anaphylactic reaction to a sting, you should carry an epinephrine auto-injector and take steps to prevent stings, including:

  • Wearing clean, light-colored clothing when outdoors
  • Avoiding perfume and scented toiletries
  • Covering up as much of your body as possible with clothing
  • Wearing closed-toe shoes outdoors
  • Staying away from food and garbage when outdoors
  • Remaining calm if a single stinging insect is flying around

Also, ask your doctor about venom immunotherapy. For this treatment, you’re regularly exposed to small amounts of the venom in a clinical setting until your immune system no longer reacts to a full-size dose of it. (10)

7. Idiopathic Anaphylaxis: When It Happens for No Known Reason

Sometimes, anaphylaxis happens for unknown reasons.
“A person is sitting there, watching TV, and has an allergic reaction,” Sicherer says of situations in which a cause can’t be found.
If you have a sudden and unexplained allergic reaction, your doctor will probably take a complete history and ask a lot of questions, such as: What did you eat or drink? Did you exercise? Did you take medication?
But sometimes, you’ll never know what triggered it. This situation baffles doctors and patients, but it’s not uncommon.
In fact, 39 percent of people with anaphylaxis may have had a reaction that can’t be explained by a known trigger, according to a study published in February 2014 in the Journal of Allergy and Clinical Immunology. (11)
If you have a history of reactions to unknown triggers, it’s important to carry an epinephrine auto-injector with you.

Additional reporting by Quinn Phillips.

Idiopathic Anaphylaxis

“There are so many potential causes and so many labs that could be done. It’s important to start out with a thorough history to narrow down which labs should be done,” Smith said. “The first thing to determine is whether it really is anaphylaxis.

“Could there be a nonimmunological explanation–perhaps a flushing syndrome or a vasovagal reaction? A true anaphylactic reaction is IgE mediated with mast cells releasing histamines that cause vasodilatation and can include hives, flushing and swelling. In addition to the cutaneous symptoms, there can be airway and GI involvement. The difference is that while other reactions may be uncomfortable, an anaphylactic reaction can be life threatening. Vasodilatation causes a drop in blood pressure with the potential for hypovolemic shock. Documented hypotension is a strong indicator of a true case of anaphylaxis.”

Ask the right questions, and you may be able to get a sense of where the problem lies before ordering labs, Smith said.

“A good place to start is with medications the patient is taking, including supplements and over the counter drugs. Even aspirin can cause problems. A new food allergy is less common in adults than in children, but you need to know everything patients have been eating. Have they had recent infections, bug bites or stings, dental procedures, or have they been in contact with latex?

“Where has the patient been that day, and what has he been doing? There are times of the year when a lot of guys say they’ve been hunting,” Smith said. “In addition to a different environment, exposure to cold, heat, and exercise can be involved. Sometimes there can be a combined reaction to food and exercise when the patient doesn’t react to the same food alone.”

Even sexual activity can be a factor, and not only because of possible contact with latex.

“Seminal fluid itself can be an allergen, or can be a problem after a man eats a food that causes an allergic reaction in his partner. It’s rare, but I’ve seen it,” Smith said.

Another possibility that recently came to light is the Alpha-Gal reaction to meats from antibodies that develop after bites from Lone Star ticks that are common in the South. The antibody binds to a carbohydrate present on beef, pork, lamb and other mammalian meats and can cause a delayed reaction up to six hours after a meal.

“This seemed to be a likely cause of the problem in the patient who was referred to me,” Smith said. “He had classic symptoms, with beef for dinner, and the onset of symptoms almost six hours later. However, the labs were negative. We were left with what continues to appear to be idiopathic anaphylaxis.”

To paraphrase Churchill, idiopathic anaphylaxis is something of a riddle wrapped in a mystery, inside an enigma. Some studies suggest that abnormalities in receptors on the surface of mast cells may be a predisposing factor. Other studies have followed hundreds of patients for many years without identifying a cause.

Whether in one specific case symptoms are occurring without an external trigger or the trigger is something that current allergy tests simply aren’t designed to identify is a difficult question. Conditions such as mastocytosis and clonal mast cell disorders are another rare possibility that can result in similar symptoms, but physicians typically evaluate the frequency of episodes and other indications before putting patients through testing that can be uncomfortable and expensive.

“To know whether you’re dealing with immunological anaphylaxis or a nonimmunologic cause, blood draws taken during the early stages of a reaction can be helpful. Histamine and tryptase levels can tell you whether you’re dealing with anaphylaxis and its severity,” Smith said. “You may want to advise patients to request the tests if there are future episodes, or have a request on file at the ER most likely to see the patient.”

Until a more specific diagnosis is possible, the key to managing idiopathic anaphylaxis is focusing on what can be done to reduce the severity and frequency of reactions and to prepare patients to deal with emergencies until they can reach medical help. Patients should have one or more EpiPens and they and their families should be trained to use them. A daily dose of medications like Zyrtec or Cingular may be helpful, and patients with frequent severe reactions may need prednisone with the dosage tapered slowly.

Smith and her mystery patient are still working to identify a specific trigger causing his problem. However, he seems to be responding well to a daily dose of Zyrtec. There have been several occasions when he began to experience the itching and redness of an impending reaction, but they resolved within a few minutes.

Now, at last, he can go to bed with a reasonable expectation of being able to sleep through the night.

Allergic reactions to foods are milder in infants, study suggests

While in older children an allergic reaction to food can be life-threatening, anaphylaxis in infants mostly manifests as hives and vomiting, the study found. With over 350 cases analyzed, including 47 infants, this is the largest study to date to describe food-induced anaphylaxis in infants under 1 year of age compared to other age groups.

“We found that infants, unlike older children, have a low-severity food-induced anaphylaxis, which should come as reassuring news to parents who are about to introduce their baby to potentially allergenic foods like peanuts,” says lead author Waheeda Samady, MD, from Lurie Children’s, who also is an Assistant Professor of Pediatrics at Northwestern University Feinberg School of Medicine. “Since early introduction of peanuts is now encouraged by national guidelines, it is understandable that parents might be fearful of triggering a serious reaction.”

The latest guidelines from the National Institute of Allergy and Infectious Diseases, released January 2017, recommend that infants be introduced to peanut-containing foods between 4 and 6 months of age. These guidelines are a major shift from previous recommendations to avoid early introduction of peanut-containing products. The current guidelines are based on a study demonstrating that early peanut introduction to high-risk infants significantly decreased their risk of developing peanut allergy.

To describe food-induced anaphylaxis in infants, Dr. Samady and colleagues conducted a retrospective review of children who presented with this condition at the Lurie Children’s emergency department over a two-year period. Their analysis included 47 infants, 43 toddlers, 96 young children and 171 school-aged children.

They found that infants presented with gastrointestinal symptoms more frequently than any other age group (89 percent of infants vs. 63 percent of toddlers, 60 percent of young children and 58 percent of school-aged children). Vomiting, in particular, was present in 83 percent of infants. Infants and toddlers also presented with skin involvement more often than school-aged children (94 percent in infants and 91 percent in toddlers vs. 62 percent in school-aged children), with hives as the most common skin manifestation found in 70 percent of infants. Any respiratory symptoms including cough were more common in older age groups (17 percent in infants vs. 44 percent in young children and 54 percent in school-aged children). Only one infant in the study presented with wheezing. Low blood pressure also was present in only one infant. No infant in the study died from anaphylaxis.

“If a baby develops only a mild rash or gastrointestinal symptoms after trying a new food, we advise parents to discuss this reaction with the child’s physician,” says senior author Ruchi Gupta, MD, MPH, from Lurie Children’s, who also is an Associate Professor of Pediatrics at Northwestern University Feinberg School of Medicine. “If there are multiple symptoms, make sure to call 911 and get emergency help immediately.”

Serious Allergic Reactions (Anaphylaxis)

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Anaphylaxis is a severe allergic reaction. Things that can cause allergic reactions are called allergens.

Anaphylaxis (pronounced: an-eh-fil-AK-siss) most often happens during allergic reactions to:

  • foods
  • insect stings
  • medicines
  • latex

Anaphylaxis can be scary. But being prepared will help you treat a reaction quickly.

What Are the Signs & Symptoms of Anaphylaxis?

Allergic reactions can cause:

  • trouble breathing
  • throat tightness or feeling like the throat or airways are closing
  • hoarseness or trouble speaking
  • wheezing
  • nasal stuffiness or coughing
  • nausea, belly pain, vomiting, or diarrhea
  • trouble swallowing
  • fast heartbeat or pulse
  • skin itching, tingling, redness, or swelling
  • hives
  • a feeling like something bad is about to happen
  • pale skin
  • passing out

Anaphylaxis can cause different symptoms at different times. It’s considered anaphylaxis if someone has:

  • any severe symptoms, such as trouble breathing, repeated vomiting, passing out, or throat tightness
  • two or more mild symptoms, such as hives and vomiting or coughing and belly pain

The person needs treatment right away.

How Is Anaphylaxis Treated?

Someone with anaphylaxis needs help right away. The reaction can get worse very quickly. So doctors usually want people with allergies to carry injectable medicine called epinephrine. Epinephrine enters the bloodstream and works quickly against serious allergy symptoms.

Doctors prescribe

auto injectors. These should always be with the person with allergies, including at school, sports, jobs, and other activities. The auto injector is small and easy to use.

If you’re prescribed epinephrine, the doctor will show you how to use it. Always have two auto injectors with you in case one doesn’t work or you need a second dose.

Your doctor also might instruct you to take antihistamines in some cases. But always treat a serious reaction with epinephrine. Never use antihistamines instead of epinephrine in serious reactions.

What to Do if You Have Anaphylaxis

Give yourself epinephrine right away if you start to:

  • have trouble breathing
  • feel tightness in your throat
  • feel faint
  • have two or more milder allergic symptoms together (like hives with coughing)

Don’t try to use an inhaler or antihistamine and wait to see what happens. Go straight for the epinephrine! Seconds count during anaphylaxis.

If you have signs of a serious allergic reaction:

  1. Use the epinephrine auto-injector right away. Then call 911.
  2. Lay down with your legs raised while you wait for the ambulance.
  3. Go to the emergency room, even if symptoms improve after epinephrine. You must be under medical supervision for several hours. This is because a second wave of serious symptoms (called a biphasic reaction) often happens. You can get more treatment at the emergency room, if you need it.

What Else Should I Know?

Being prepared can help you stay safe:

  • Carry two epinephrine auto injectors with you at all times. Epinephrine can be a lifesaver.
  • Avoid the things you are allergic to.
  • Let friends, teachers, and coaches know about your allergies and how they can help you if you have a reaction.

Reviewed by: Larissa Hirsch, MD Date reviewed: November 2019


What is anaphylaxis?

Anaphylaxis is a serious and potentially life-threatening allergic reaction. Normally, when you are allergic to a substance, the body’s immune system overreacts by releasing chemicals. These chemicals cause the annoying symptoms — itchy, watery eyes, runny nose — of an allergy.

However, in some people, this reaction is much more severe, and anaphylaxis is the result. Symptoms of anaphylaxis may include swelling, hives, lowered blood pressure, shortness of breath, wheezing, and difficulty swallowing.

In these cases, a person can go into anaphylactic shock. Blood pressure drops severely and swelling occurs in the bronchial tissues, causing symptoms of choking and loss of consciousness. If anaphylactic shock isn’t treated immediately, it can be fatal.

What are the most common causes of anaphylaxis?

Food allergy is a recognized cause of anaphylaxis. Foods that may cause anaphylaxis include:

Venom allergies (for example, allergy to bee or wasp stings) can also cause anaphylaxis.

Some substances can cause reactions, called anaphylactoid reactions, that are similar to and just as serious as anaphylaxis. Aspirin, other nonsteroidal anti-inflammatory drugs, and dye given for CT scans can cause these reactions.

Pollens and other inhaled allergens (allergy-causing substances) rarely cause anaphylaxis.

What are the symptoms of anaphylaxis?

Anaphylaxis may begin with severe itching of the eyes or face. Within minutes, it can move on to more serious symptoms, including:

  • Swelling, which can cause problems with swallowing and breathing
  • Abdominal (belly) pain
  • Cramps
  • Vomiting
  • Diarrhea
  • Hives and angioedema (swelling)

If you have symptoms of anaphylaxis, get medical help immediately. The condition can quickly cause increased heart rate, sudden weakness, a drop in blood pressure, shock, and ultimately unconsciousness and even death.

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