Does diarrhea make you dehydrated

What Causes Vomiting and Diarrhea? 

What is stomach flu and what are the symptoms?

The stomach flu is an infection of the gut, which often causes vomiting and diarrhea. It can also cause you to feel tired and have a slight fever.

Viral or bacterial infections are often to blame. You usually catch the stomach flu if you eat or drink food or water that is contaminated with infections (caused by bacteria, viruses or parasites). You can also catch it if you come in contact with a person who is unwell, such as by breathing in vomit particles that spray into the air (they can fly as far as 10 feet!).

Other names for gastrointestinal infections include – gastro, food poisoning, travelers’ diarrhea, stomach bug, stomach flu, gastro distress, gastro flu, norovirus, Montezuma’s revenge, and gastroenteritis.

An average male can lose up to 3 L of fluid during a case of the stomach flu*! This loss of water and electrolytes causes mild to moderate dehydration.

*Mild dehydration, 4% fluid deficit, in a 80 kilos adult

Dehydration is the biggest health risk associated with the stomach flu and can occur more quickly for small babies, children, and the elderly. If dehydration becomes severe, you can end up in the hospital on a fluid drip.

  • What Is Diarrhea?
  • What Causes Diarrhea?
  • What Are the Symptoms?
  • Diarrhea in Children
  • What Is Dehydration?
  • When Should a Doctor Be Consulted?
  • What Tests Might the Doctor Do?
  • What Is the Treatment?
  • Preventing Traveler’s Diarrhea
  • Points To Remember

Diarrhea–loose, watery stools occurring more than three times in one day–is a common problem that usually lasts a day or two and goes away on its own without any special treatment. However, prolonged diarrhea can be a sign of other problems. Diarrhea can cause dehydration, which means the body lacks enough fluid to function properly. Dehydration is particularly dangerous in children and the elderly, and it must be treated promptly to avoid serious health problems. Dehydration is discussed below. People of all ages can get diarrhea. The average adult has a bout of diarrhea about four times a year.
What Causes Diarrhea? Diarrhea may be caused by a temporary problem, like an infection, or a chronic problem, like an intestinal disease. A few of the more common causes of diarrhea are

  • Bacterial infections. Several types of bacteria, consumed through contaminated food or water, can cause diarrhea. Common culprits include Campylobacter, Salmonella, Shigella, and Escherichia coli.
  • Viral infections. Many viruses cause diarrhea, including rotavirus, Norwalk virus, cytomegalovirus, herpes simplex virus, and viral hepatitis.
  • Food intolerances. Some people are unable to digest a component of food, such as lactose, the sugar found in milk.
  • Parasites. Parasites can enter the body through food or water and settle in the digestive system. Parasites that cause diarrhea include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.
  • Reaction to medicines, such as antibiotics, blood pressure medications, and antacids containing magnesium.
  • Intestinal diseases, like inflammatory bowel disease or celiac disease.
  • Functional bowel disorders, such as irritable bowel syndrome, in which the intestines do not work normally.

Some people develop diarrhea after stomach surgery or removal of the gallbladder. The reason may be a change in how quickly food moves through the digestive system after stomach surgery or an increase in bile in the colon that can occur after gallbladder surgery. In many cases, the cause of diarrhea cannot be found. As long as diarrhea goes away on its own, an extensive search for the cause is not usually necessary. People who visit foreign countries are at risk for traveler’s diarrhea, which is caused by eating food or drinking water contaminated with bacteria, viruses, or, sometimes, parasites. Traveler’s diarrhea is a particular problem for people visiting developing countries. Visitors to the United States, Canada, most European countries, Japan, Australia, and New Zealand do not face much risk for traveler’s diarrhea.
What Are the Symptoms? Diarrhea may be accompanied by cramping abdominal pain, bloating, nausea, or an urgent need to use the bathroom. Depending on the cause, a person may have a fever or bloody stools. Diarrhea can be either acute or chronic. The acute form, which lasts less than 3 weeks, is usually related to a bacterial, viral, or parasitic infection. Chronic diarrhea lasts more than 3 weeks and is usually related to functional disorders like irritable bowel syndrome or diseases like celiac disease or inflammatory bowel disease.
Diarrhea in Children Children can have acute (short-term) or chronic (long-term) forms of diarrhea. Causes include bacteria, viruses, parasites, medications, functional disorders, and food sensitivities. Infection with the rotavirus is the most common cause of acute childhood diarrhea. Rotavirus diarrhea usually resolves in 5 to 8 days. Medications to treat diarrhea in adults can be dangerous to children and should be given only under a doctor’s guidance. Diarrhea can be dangerous in newborns and infants. In small children, severe diarrhea lasting just a day or two can lead to dehydration. Because a child can die from dehydration within a few days, the main treatment for diarrhea in children is rehydration. Rehydration is discussed below. Take your child to the doctor if any of the following symptoms appear:

  • Stools containing blood or pus, or black stools
  • Temperature above 101.4 degrees Fahrenheit
  • No improvement after 24 hours
  • Signs of dehydration (see below)

What Is Dehydration?

General signs of dehydration include:

  • Thirst
  • Less frequent urination
  • Dry skin
  • Fatigue
  • Light-headedness
  • Dark colored urine

Signs of dehydration in children include:

  • Dry mouth and tongue
  • No tears when crying
  • No wet diapers for 3 hours or more
  • Sunken abdomen, eyes, or cheeks
  • High fever
  • Listlessness or irritability
  • Skin that does not flatten when pinched and released

If you suspect that you or your child is dehydrated, call the doctor immediately. Severe dehydration may require hospitalization.
When Should a Doctor Be Consulted? Although usually not harmful, diarrhea can become dangerous or signal a more serious problem. You should see the doctor if:

  • You have diarrhea for more than 3 days.
  • You have severe pain in the abdomen or rectum.
  • You have a fever of 102 degrees Fahrenheit or higher.
  • You see blood in your stool or have black, tarry stools.
  • You have signs of dehydration.

If your child has diarrhea, do not hesitate to call the doctor for advice. Diarrhea can be dangerous in children if too much fluid is lost and not replaced quickly.
What Tests Might the Doctor Do? Diagnostic tests to find the cause of diarrhea include the following:

  • Medical history and physical examination. The doctor will need to know about your eating habits and medication use and will examine you for signs of illness.
  • Stool culture. Lab technicians analyze a sample of stool to check for bacteria, parasites, or other signs of disease or infection.
  • Blood tests. Blood tests can be helpful in ruling out certain diseases.
  • Fasting tests. To find out if a food intolerance or allergy is causing the diarrhea, the doctor may ask you to avoid lactose (found in milk products), carbohydrates, wheat, or other foods to see whether the diarrhea responds to a change in diet.
  • Sigmoidoscopy. For this test, the doctor uses a special instrument to look at the inside of the rectum and lower part of the colon.
  • Colonoscopy. This test is similar to sigmoidoscopy, but the doctor looks at the entire colon.

What Is the Treatment? In most cases, replacing lost fluid to prevent dehydration is the only treatment necessary. (See “Preventing Dehydration” below.) Medicines that stop diarrhea may be helpful in some cases, but they are not recommended for people whose diarrhea is from a bacterial infection or parasite–stopping the diarrhea traps the organism in the intestines, prolonging the problem. Instead, doctors usually prescribe antibiotics. Viral causes are either treated with medication or left to run their course, depending on the severity and type of the virus. Preventing Dehydration
Dehydration occurs when the body has lost too much fluid and electrolytes (the salts potassium and sodium). The fluid and electrolytes lost during diarrhea need to be replaced promptly–the body cannot function properly without them. Dehydration is particularly dangerous for children, who can die from it within a matter of days. Although water is extremely important in preventing dehydration, it does not contain electrolytes. To maintain electrolyte levels, you could have broth or soups, which contain sodium, and fruit juices, soft fruits, or vegetables, which contain potassium. For children, doctors often recommend a special rehydration solution that contains the nutrients they need. You can buy this solution in the grocery store without a prescription. Examples include Pedialyte, Ceralyte, and Infalyte. Tips About Food
Until diarrhea subsides, try to avoid milk products and foods that are greasy, high-fiber, or very sweet. These foods tend to aggravate diarrhea. As you improve, you can add soft, bland foods to your diet, including bananas, plain rice, boiled potatoes, toast, crackers, cooked carrots, and baked chicken without the skin or fat. For children, the pediatrician may recommend what is called the BRAT diet: bananas, rice, applesauce, and toast.
Preventing Traveler’s Diarrhea Traveler’s diarrhea happens when you consume food or water contaminated with bacteria, viruses, or parasites. You can take the following precautions to prevent traveler’s diarrhea when you go abroad:

  • Do not drink any tap water, not even when brushing your teeth.
  • Do not drink unpasteurized milk or dairy products.
  • Do not use ice made from tap water.
  • Avoid all raw fruits and vegetables (including lettuce and fruit salad) unless they can be peeled and you peel them yourself.
  • Do not eat raw or rare meat and fish.
  • Do not eat meat or shellfish that is not hot when served to you.
  • Do not eat food from street vendors.

You can safely drink bottled water (if you are the one to break the seal), carbonated soft drinks, and hot drinks like coffee or tea. Depending on where you are going and how long you are staying, your doctor may recommend that you take antibiotics before leaving to protect you from possible infection.
Points To Remember

  • Diarrhea is a common problem that usually resolves on its own.
  • Diarrhea is dangerous if a person becomes dehydrated.
  • Causes include viral, bacterial, or parasitic infections; food intolerance; reactions to medicine; intestinal diseases; and functional bowel disorders.
  • Treatment involves replacing lost fluids and electrolytes. Depending on the cause of the problem, a person might also need medication to stop the diarrhea or treat an infection. Children may need an oral rehydration solution to replace lost fluids and electrolytes.
  • Call the doctor if a person with diarrhea has severe pain in the abdomen or rectum, a fever of 102 degrees Fahrenheit or higher, blood in the stool, signs of dehydration, or diarrhea for more than 3 days.

Last Reviewed: January 2001

What Causes Vomiting and Diarrhea?

How Hydralyte can help relieve mild stomach flu symptoms?

The stomach flu is an infection of the gut, which often causes vomiting and diarrhea. It can also cause you to feel tired and have a slight fever. Dehydration is the biggest health risk associated with the stomach flu and can occur more quickly for small babies, children, and the elderly. If dehydration becomes severe, you can end up in the hospital on a fluid drip. This is where Hydralyte comes in – the Hydralyte formula is designed to replenish those key electrolytes that may have been lost during vomiting or diarrhea due to viral or bacterial stomach infections. Viral or bacterial infections are often to blame for the flu. You usually catch the stomach flu if you eat or drink food or water that is contaminated with infections (caused by bacteria, viruses or parasites). You can also catch it if you come in contact with a person who is unwell, such as by breathing in vomit particles that spray into the air (they can fly as far as 10 feet!). Other names for gastrointestinal infections include – gastro, food poisoning, travelers’ diarrhea, stomach bug, stomach flu, gastro distress, gastro flu, norovirus, and Montezuma’s revenge. An average male can lose up to 3.2 QT (3 L) of fluid during a case of the stomach flu*! This loss of water and electrolytes causes mild to moderate dehydration.

*Mild dehydration, 4% fluid deficit, in a 176 lbs adult

Dehydration Symptoms

Being thirsty isn’t the only clue that you’re dehydrated. For adults, other signs include:

  • You pee less often than normal.
  • Your urine is dark-colored.
  • You have muscle cramps.
  • You’re easily fatigued.
  • You feel light-headed, especially when you stand up..
  • You don’t sweat as much as normal.

By the time these symptoms show up, dehydration may be far along. At the first sign of diarrhea or vomiting, you need to start to replace lost water and the salts you need called electrolytes.

Water is just part of the answer. It rehydrates the body. But you’ll still need the salts.

If you have prolonged or severe diarrhea or if you’re vomiting, most experts recommend drinking rehydration solutions — special fluids that give your body salt and water. You can also drink juice that has some potassium and broth for sodium — they aren’t substitutes for rehydration solutions, but they may help mild dehydration not become worse.

Your doctor can also prescribe nausea medicine if your nausea and vomiting are severe.

Call your doctor if diarrhea or vomiting lasts for more than 2 days. Call sooner if there’s a fever or pain in the abdomen or rectum, if stool appears black or tarry, or if signs of dehydration appear.

How to Properly Rehydrate After Diarrhea

Oftentimes, diarrhea is caused by our body’s natural immune response to an unwanted microorganism in the gut. During an episode of diarrhea, your body sends water to your digestive tract to flush out the unwelcome intruders. This flushing process uses your body’s water and important nutrients, and can cause dehydration if you don’t effectively replace the lost fluids.

Dehydration from diarrhea can cause serious issues like muscle cramps, lightheadedness, fatigue, and in extreme cases, death. That’s why rehydrating during and after your bout of diarrhea is essential. Once you’ve got your diarrhea under control, here are the best ways to properly rehydrate.

Water Isn’t Enough

While drinking plain water is helpful during and after diarrhea, your body loses electrolytes and other important nutrients which can’t be replaced by water only. That’s why water infused with nutrients is the safest way to rehydrate after diarrhea.

What to Drink – Oral Rehydration Solutions

An oral rehydration solution (ORS) is a drinkable solution that helps to rehydrate better than water alone. Any ORS should contain three ingredients:

Clean Water

The water used in an ORS should be clean – from either commercially-sealed water bottles or reputable tap sources. If you don’t have access to clean water, boil water for one to three minutes to purify it.


Electrolytes commonly included in oral rehydration solutions include sodium, calcium, potassium, and magnesium (among others). These electrolytes help regulate your body’s water balance, acid/base levels, and nerve and muscle function.


The carbohydrate in most oral rehydration solutions is sugar, which is easy for your body to absorb and use as energy.

How to Drink – Oral Rehydration Solutions

You can either make a homemade electrolyte drink with coconut water, salt, and calcium-magnesium, or purchase an electrolyte beverage from your local grocery store.

Children ages two to nine should drink ½ to 1 cup of oral rehydration solution for each episode of diarrhea. Kids and adults over the age of ten should drink ORS whenever they feel thirsty, up to 2 liters (8 cups) per day. The elderly population should drink more frequently because they are not as sensitive to thirst and may experience dehydration faster.

What to Avoid

While rehydrating, avoid alcohol and caffeinated beverages, which can lead to greater dehydration and fatigue. Also, avoid high-fat and high-sugar beverages; instead, stick to drinks that are generally easy to digest.

Feeling Better After Diarrhea

While replacing lost fluids and nutrients is crucial for proper rehydration, quickly relieving your diarrhea is the best way to avoid potentially dangerous dehydration.

As soon as you experience diarrhea symptoms, consider taking DiaResQ, a food for special dietary use that supports your body’s natural immune response, providing beneficial nutrients and immune factors that help to relieve diarrhea and restore normal intestinal function. DiaResQ taken with an ORS is a safe way to relieve diarrhea quickly, without the use of drugs. Relieve diarrhea and properly rehydrate your body quickly, so you can get back to your normal routine.

Hydrating and rehydrating when you have gastroenteritis

Follow the rehydration and dietary instructions for the symptoms of diarrhea without dehydration or diarrhea with dehydration.

Diarrhea with dehydration

Symptoms of diarrhea with dehydration are:

  • increased thirst,
  • decreased urine output,
  • dry mouth.


Use a rehydration solution. To find out how much solution you should drink and when, call Info-Santé 811. A nurse will tell you exactly what to do depending on your or your child’s condition.


  • Stop eating temporarily (for about 3 to 4 hours).
  • When the vomiting subsides, gradually start eating again: eat small amounts of food at a time, but eat more often.
  • Go to the page Foods to eat when you have gastroenteritis to find out which foods are best.

Diarrhea without dehydration

  • Drink more fluids. You can drink water, but if you are not eating, have a rehydration solution too. If your child is breast or bottle fed, they can drink their usual milk
  • If you are using a commercial rehydration solution, follow the instructions on the package
  • If you are using a homemade rehydration solution, call Info-Santé 811 to find out how much solution you should drink and when. A nurse will tell you exactly what to do depending on your or your child’s condition
  • If you or your child are vomiting, drink small amounts of fluids more often

Eat several small meals. Go to the page Foods to eat when you have gastroenteritis to find out which foods are best.

For people at risk of complications

If you or your child are among those people likely to experience complications, call Info-Santé 811. A nurse will give you rehydration and dietary instructions that are appropriate for your or your child’s situation.

Rehydrating After Diarrhea


What’s the best way to rehydrate after a bout of diarrhea? Nutritional supplements, sports drinks, water, or something else?


This is a great question as diarrhea is one of the biggest contributors to dehydration and malabsorption of nutrients. The degree of dehydration will determine the best treatment for rehydration.

It is important to respond quickly at the first signs of mild dehydration (i.e., dry mouth and thirst) by treating with consistent water intake and electrolyte replacement. In very mild cases, when there are no symptoms other than dry mouth and thirst, it is adequate to drink lots of water, non-caffeinated teas, 100% fruit juices and other beverages that don’t contain added sugars, alcohol or caffeine until symptoms disappear. Beverages containing alcohol, caffeine and added sugars should be avoided, as they contribute to dehydration rather than improve it. Electrolytes can be consumed by eating potassium, magnesium and sodium-rich foods that are tolerated.

When more severe dehydration sets in, with symptoms such as thirst, lack of urination, dry skin, fatigue, light-headedness or inability to sweat, it is important to see a doctor immediately to seek their advice.

If diarrhea persists for more than 3 days, with or without the above-stated symptoms, it is still a good idea to see a doctor, as dehydration can set in very quickly.

While waiting for medical attention, it is best to drink as much as possible of water, sports drinks, fruit drinks and broth, as well as to salt food and beverages. If getting liquids down is hard to do, try sucking on ice cubes or fruit popsicles.

When treating a dehydrated child, doctors often recommend over-the-counter replacement formulas, which have the ideal balance of water, sugar and salt for younger bodies. Please make sure to check the labels to ensure these products are gluten-free.

In the most severe cases of dehydration, when an individual is experiencing low blood pressure, fainting, muscle contractions, rapid and/or deep breathing or a fast, weak pulse, take them to the emergency room immediately.

Lastly, read all labels to be sure that what is being consumed is gluten-free. Diarrhea is one of the most common symptoms experienced by those with celiac disease and gluten sensitivity. Consuming a gluten-containing item will exacerbate the diarrhea in the short term as well as trigger the autoimmune response that damages the intestines.

Be well,

Rachel Begun, MS, RD

Related Content:

  • Celiac Disease Symptoms
  • Study Estimates Global Prevalence and Mortality Rate of Celiac Disease in Children Under Age 5

Vomiting and Diarrhoea

Vomiting and diarrhoea can be caused by highly contagious viral infections, and can spread through your family fast. It’s no fun for anyone.

The biggest risk associated with vomiting and diarrhoea is dehydration from losing a large amount of fluid and electrolytes. Dehydration can be alleviated by sipping on small amounts of an electrolyte solution like Hydralyte while you recover and get back on your feet.

You can recover faster by rehydrating with an electrolyte solution like Hydralyte.

What causes vomiting and diarrhoea?

Tummy bugs come in many shapes and forms.

There are viral infections like rotavirus and norovirus, which can spread like wildfire through child-care centres, aged-care facilities and hospitals. If your family is suffering through an outbreak of vomiting and diarrhoea, then it’s likely you’ve all got the same viral infection.

Viral pathogen Incubation period Average illness duration
A highly contagious virus, and the leading cause of acute gastroenteritis worldwide. Norovirus particles can live on surfaces for about three days, and in water for two weeks; and are resistant to many cleaning products.
18-48 hours 24-48 hours
A common cause of vomiting and diarrhoea, especially in young infants and children.
< 48 hours Up to 5 days

Then there are bacterial infections like E.coli and salmonella. Think of these as food poisoning – they are usually isolated to one unfortunate person. Just as nasty, but not likely to spread.

Bacterial pathogen Incubation period Average illness duration
Escherichia coli
E.coli is a common bacterial infection found in contaminated water or foods like raw vegetables and undercooked ground beef.
12 hours to 3 days 1 week
Salmonella spp.
A major public health problem in the developing world, transmitted by the ingestion of contaminated food. Salmonella particles can survive at -20C!
24-48 hours (up to 72 hours) Days to weeks depending on amount ingested
Shigella spp.
A bacterial infection that can cause severe vomiting and diarrhoea.
1-3 days 3 days
Campylobacter jejuni
A major cause of food poisoning in Australia.
1-7 days 1-7 days
Giardia duodenalis
Giardiasis is an infection in the bowel caused by a parasite. It is common amongst travellers to underdeveloped countries like Bali and India.
12-15 days Weeks to months

Some other conditions can cause vomiting and diarrhoea. Morning sickness, some medications and other stomach conditions can trigger an outbreak, leaving you feeling very depleted and dehydrated.

How to prevent the spread of viral infections

If one of your family members have been struck down with an infection that causes vomiting or diarrhoea. You should:

  • Wash your hands in soapy water after nappy changes and going to the toilet, and before food preparation or eating
  • Try to cover vomit (close the toilet lid immediately) to avoid the airborne spread of particles
  • Clean contaminated surfaces with detergent, warm water and bleach
  • Avoid vacuuming, as this can spread viral particles

If your child is vomiting or has diarrhoea, keep them home from childcare or school for a minimum of 48 hours, and avoid swimming pools for 14 days after the symptoms stop.

Monitoring your child

If your child is vomiting or has diarrhoea, then it’s very important to keep track of their fluid intake. Children (and the elderly) are more at risk.

It’s recommended that you keep a record of how much fluid your child is taking in, versus how often they are vomiting or going to the toilet. Make these observations every 15 minutes – the information will be useful for your doctor.

Top tip: offer your child the Hydralyte Electrolyte Ice Block to suck on.

Download our Oral Fluid Intake Chart

Rehydrating with Hydralyte

Hydralyte is scientifically formulated to contain the correct balance of glucose and electrolytes for rapid rehydration. The formulation is based on the World Health Organisation criteria for effective rehydration. Water alone, or sugary drinks are not as effective as Hydralyte, as they do not replace electrolytes which are lost during bouts of vomiting and diarrhoea


Age in years Electrolyte powder and Electrolyte solution Effervescent Electrolyte Tablets (recommended dose in first 6 hours)
Under 12 months 100mL / 90 mins 200-400mL
1-3 years 100mL / 90 mins 400-600mL
3-6 years 100mL / 60 mins 600-900mL
7-12 years 100mL / 30 mins 900-1500mL
Over 12 years 200mL / 30 mins 1200-2000mL

Continue to use Hydralyte while vomiting and/or diarrhoea persist and while symptoms of dehydration are present.

When can you eat food again?

Once you or your child is able to keep down significant fluids, you can gradually reintroduce solid foods. Avoid sweet, fatty and spicy foods – instead, try things like rice, potatoes, bread, cooked cereals and dry biscuits.


Seek medical advice if vomiting or diarrhoea persists for more than:

  • 6 hours in infants under 6 months
  • 12 hours in children under 3 years
  • 24 hours in children aged 3-6 years
  • 48 hours in children over 6 years and adults

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