Diarrhea: Causes, symptoms, treatment and prevention

Diarrhea is one of the most common diseases of the digestive system. The disease can appear at any age with varying degrees of severity. If not properly treated, this disease can cause many complicated, even life-threatening complications. Readers, please refer to the following article of General Internal Medicine specialist Nguyen Lam Giang to better understand this very common digestive disease.

Diarrhea definition and classification

Diarrhea (or diarrhea) is the passage of loose, watery stools three or more times in a day. This disease can be classified as acute, persistent or chronic:

  • Acute diarrhea is a very common illness that usually lasts 1 or 2 days and usually resolves on its own.
  • Diarrhea is said to be persistent when it lasts more than 2 weeks and less than 4 weeks.
  • Diarrhea is said to be chronic when the illness lasts for at least 4 weeks. Symptoms of chronic diarrhea may be intermittent; Or it can appear and disappear.

Diarrhea is a fairly common disease, occurring in all ages

Diarrhea is a fairly common disease, occurring in all ages

Causes of diarrhea

Acute, persistent and chronic diarrhea depend on different causes, namely:

Causes of acute, persistent diarrhea

The most common causes of acute and persistent diarrhea are infections, environmental changes (business travel, travel to new lands), and medication side effects.


The three main types of infections that cause diarrhea include:

  • Viral infection. Many viruses cause loose stools, the most common being Norovirus and Rotavirus.3 4 Viral gastroenteritis is a common cause of acute diarrhea.
  • Infection. Certain types of bacteria can enter the human body through contaminated food or water and cause illness. Common bacteria that cause diarrhea include Campylobacter, Escherichia coli (E. coli), Salmonella, Shigella (Bacterial dysentery).
  • Parasitic infection. Parasites can enter the body of an infected person through food or water and live in the human digestive tract. Parasites that cause diarrhea: Cryptosporidium enteritis, Entamoeba histolytica and Giardia lamblia.

An infection in the digestive tract that is spread through food or drink is called food poisoning. Infections lasting more than 2 weeks and less than 4 weeks can cause persistent diarrhea.

Campylobacter infections can cause acute or persistent diarrhea

Campylobacter infections can cause acute or persistent diarrhea

Changing the environment (when going on a business trip, traveling in a new land)

This diarrhea is caused by food contaminated with bacteria, viruses, or parasites. The occurrence is usually acute. However, some parasites can make loose stools last longer. This disease is often a common situation of travelers to tropical countries or developing countries.

Side effects of some medications

Some medications can cause loose, watery stools. Such drugs include antibiotics, magnesium-containing drugs, and cancer drugs.

Causes of chronic persistent diarrhea

Certain medical conditions can cause loose stools that last for weeks or even months. Such as:

  • Infection.
  • Food allergies and intolerances.
  • Diseases of the gastrointestinal tract.
  • History of abdominal surgery.
  • Long-term use of some drugs causes diarrhea side effects.


Some bacterial and parasitic infections can cause diarrhea. Besides, the disease will not heal quickly if not treated appropriately.

In addition, after infection, the person may experience dysfunction in the digestion of carbohydrates such as lactose or dysfunction in the digestion of proteins in foods such as cow’s milk, dairy products, or legumes. These digestive disorders can make the diarrhea last longer.

Lactose intolerance can cause diarrhea

Lactose intolerance can cause diarrhea

Food allergies and intolerances

1. Food allergy

Food allergy is an allergy to foods such as cow’s milk, soy, grains, eggs, seafood, etc. This type of allergy can cause chronic diarrhea that lasts.

2. Lactose intolerance

Lactose intolerance is a common condition that can cause diarrhea after consuming milk or dairy products (cheese, milkshakes, etc.).

3. Fructose intolerance

Fructose intolerance is a condition that can cause diarrhea after eating foods or drinking liquids that contain fructose, a type of sugar found in fruit, fruit juices, and honey. Fructose is added to many foods and beverages as a sweetener known as high-fructose corn syrup.2

4. Allergy to certain substances in food

Sugar alcohols (Sugar alcohols are organic compounds, usually derived from sugar, consisting of a polyol layer. They are white, water-soluble solids that can occur naturally or industrially from sugar) . Sugar alcohols such as sorbitol, mannitol, and xylitol can cause diarrhea in some people. Sugar-free candies and chewing gum often include these substances.

Digestive tract diseases

Gastrointestinal conditions that can cause chronic diarrhea include:

  • Celiac disease.
  • Crohn’s disease.
  • Irritable bowel syndrome.
  • Small intestinal bacterial overgrowth.
  • Ulcerative colitis.

Irritable bowel syndrome is one of the leading causes of chronic diarrhea

Irritable bowel syndrome is one of the leading causes of chronic diarrhea

Abdominal surgery

Patients may experience chronic diarrhea after abdominal surgery. May include: Surgery of the appendix, gallbladder, small intestine, large intestine, hepatobiliary tract, pancreas, stomach, spleen.

Long-term use of certain drugs

Some medications, when used long-term, can cause chronic liquid diarrhea as a side effect. Antibiotics, for example, can change the beneficial bacteria in the gut and increase the risk of infection with Clostridioides difficile, a bacteria that can cause chronic diarrhea.

Symptoms of diarrhea and dehydration

The main symptom of diarrhea is passing loose, watery stools 3 or more times in a day. There are many associated symptoms that vary and depend on the underlying cause. Patients may experience only one or more of the following symptoms:

Symptoms in adults

  • Common symptoms of diarrhea
  • Abdominal pain.
  • Straining, difficult to control bowel movements.
  • Nausea, vomiting.
  • Loose, watery stools that may be bloody, foamy, or cloudy like rice water in the case of cholera infection.
  • Stomach distended.
  • Cramp.
  • Loss of water.

Frequent bowel movements, loose stools, or severe abdominal pain are common symptoms of diarrhea

Frequent bowel movements, loose stools, or severe abdominal pain are common symptoms of diarrhea

Symptoms of diarrhea due to infection

People with diarrhea caused by certain infections may also have one or more of the following symptoms:

  • Bloody stools.
  • Fever, which may be high with or without chills.
  • Dizziness and lightheadedness.
  • Dry lips, dirty tongue, bad breath.

Symptoms of dehydration

Diarrhea can make you dehydrated quickly. If you don’t get treatment in time, this condition can be very dangerous. Therefore, you also need to pay attention to the following signs of dehydration:

  • Tired, exhausted, lethargic.
  • Mucous membrane dryness.
  • The heart rate increases suddenly.
  • Headache, feeling lightheaded.
  • Constant thirst.
  • Urinating less.
  • Dark urine.
  • Dry mouth.
  • Emaciated face, sunken eyes, dry skin.
  • Pale skin, tongue loss of spines.

Dry, pale, emaciated skin signals your body is dehydrated due to diarrhea

Dry, pale, emaciated skin signals your body is dehydrated due to diarrhea

When detecting symptoms of dehydration, patients should immediately seek medical attention for timely treatment.

Symptoms of diarrhea in children

Children are the subjects that need special attention when they have diarrhea and dehydration.

The CDC reports that diarrhea and its complications are 1 in 9 causes of death each year in children worldwide, making it the second leading cause of death in children under 5 years of age.

Symptoms of diarrhea and dehydration in children:

  • Urinating less and less.
  • Dry mouth.
  • Headache.
  • Tired.
  • Crying without tears.
  • Dry skin.
  • Deep sunken eyes.
  • Sleepy.
  • Or grumpy.

Babies who are fussy but have no tears can be a sign of dehydration

Babies who are fussy but have no tears can be a sign of dehydration

How to treat yourself at home for diarrhea?

Research shows that the principle when treating diarrhea is to make up for lost fluids. This means you need to rehydrate by drinking extra water or an electrolyte replacement drink. Besides, you can also treat acute diarrhea with some over-the-counter medicines.2 20

Translation compensation

Oral rehydration may help reduce events caused by dehydration. Drinks that we can make at home such as: Salted rice water, salted yogurt, salted coconut water. If you have a pack of Oresol powder available, even better.

Patients should drink slowly to avoid vomiting, especially children. When drinking should pay attention to drink slowly, do not drink quickly, especially children. Because electrolyte replacement solution has a slightly unpleasant taste, it may cause nausea and vomiting.

How to make: Use 1 cup of rice water or a box of liquid yogurt or 1 cup of coconut water (about 50-100ml). Then add a pinch of salt and stir until completely dissolved.

For the Oresol powder pack, mix it with 50-100ml of warm water. Young children give each spoonful, older children can give sips, cup by cup. Drink after each bowel movement. For acute diarrhea, the average time is from 3 to 5 days, the number of times is equal to the number of diarrhea or drinking on demand (when thirsty).

Replenish with salted coconut water

Replenish with salted coconut water

Using over-the-counter drugs

In most cases, you can treat acute diarrhea with over-the-counter medications such as Loperamide (Imodium) and Bismuth subsalicylate (Pepto-Bismol, Kaopectate), Smecta, Carbomango, etc. Doctors often discourage its use. over-the-counter medicine for people with bloody stools or fever – signs of a bacterial or parasitic infection. If diarrhea persists for more than 2 days, seek medical attention immediately.

Note when using over-the-counter drugs:

These drugs can temporarily stop acute diarrhea so that we have time to take the patient to a medical facility. You need to read the instructions on the package; see what doses of these medicines to take and when to take them; do not use more than recommended by the label; and  also do not take more than one of these medicines at the same time. Over-the-counter diarrhea medications are also not recommended for patients with bloody or feverish stools.

Smecta anti-diarrheal medicine – you should consult your doctor before taking

Smecta anti-diarrheal medicine – you should consult your doctor before taking


Over-the-counter medications to treat acute diarrhea in adults can be dangerous for infants, toddlers, and young children. You should consult a specialist before giving your child over-the-counter medications. If your child’s diarrhea persists for more than 24 hours, seek medical attention right away.2

Reasonable diet

When you have diarrhea, you may lose your appetite for a short time. In most cases, when your appetite returns, you can go back to your normal diet. Parents and caregivers should feed children with diarrhea the normal age-appropriate diet. For younger babies, you can continue to give breast milk or formula.

The continuation of a normal eating schedule will help speed up the recovery of intestinal physiology. At the time of illness, the patient should eat a full range of protein, sugar, fat, vitamins, and fiber. Prioritize soft, easy-to-digest foods such as porridge, noodles, soup, etc.

Bananas, biscuits, toast are foods you can supplement when you have diarrhea

Bananas, biscuits, toast are foods you can supplement when you have diarrhea

When to see a doctor?

Diarrhea can become dangerous if it causes severe dehydration. Therefore, when detecting a patient with the following symptoms, it is necessary to take them to the hospital immediately:2

Symptoms in adults

Adults with any of the following symptoms should see a doctor immediately:

  • Massive diarrhea lasting more than 2 days.
  • Fever of 39°C or higher.
  • Vomiting frequently and continuously.
  • Cramping, severe pain in the abdomen or rectum.
  • Stools that are black, have a foul smell, have blood or pus.

Older adults and adults with weakened immune systems are rapidly depleted after frequent watery stools.

Symptoms in infants and young children

Parents or caregivers of an infant or young child with diarrhea should take the child to the doctor immediately in the following situations:

  • Diarrhea lasts more than 1 day.
  • High fever of 39°C or higher.
  • Babies cry, stop sucking, suck poorly.
  • Stools with a lot of blood or pus.
  • Black pepper.
  • Severe dehydration: Sunken eyes, dry skin, lethargy, possibly convulsions.
  • No reaction.

Children should be taken to the doctor as soon as they show signs of lethargy and diarrhea

Children should be taken to the doctor as soon as they show signs of lethargy and diarrhea

How do doctors diagnose diarrhea?

For acute diarrhea, finding the exact cause is not necessary. However, with diarrhea lasting more than 4 days or accompanied by dangerous symptoms (fever, bloody stools); The doctor will adopt the following ways to find the cause of the disease:

Learn about your medical and family history

Your doctor will ask for information about your symptoms, such as:

  • How long have you had diarrhea?
  • Is the amount of faeces released a lot or not?
  • Do you often have diarrhea?
  • Stool status. Such as color or consistency/liquidity.
  • Other accompanying symptoms.

In addition, your doctor will ask about the foods you have recently consumed. If your doctor suspects you have a food allergy or intolerance, they will advise you to change your daily diet. At the same time, the doctor and you will monitor the diarrhea symptoms to improve or not?

Your doctor will also ask about:

  • Your current state.
  • Current prescription and non-prescription drugs.
  • History of recent contact with people who are sick.
  • Recent travel history in developing countries.

Also, your doctor may ask if anyone in your family has a history of medical conditions that cause chronic diarrhea; such as Celiac disease, Crohn’s disease, irritable bowel syndrome, lactose intolerance and ulcerative colitis.

General health check

During the visit, the doctor will also perform general health checks such as:

  • Check your blood pressure and pulse for signs of dehydration.
  • Check your body for signs of fever or dehydration.
  • Use a stethoscope to listen to sounds in your abdomen.
  • Lightly tap your abdomen to check for pain.

Sometimes, doctors perform a rectal exam. Your doctor will ask you to bend over the table or lie on your side while holding your knees close to your chest. After putting on gloves, the doctor will slide a lubricated finger into your anus to check for blood in your stool.

Perform tests

The following tests are used to help doctors find the cause of a patient’s diarrhea.

Stool test

Stool tests may reveal the presence of blood, bacteria, or parasites; or signs of other diseases and disorders.

Blood tests

A lab technician or doctor may take a blood sample to test for certain diseases or disorders that can cause diarrhea.

Hydrogen breath test

This test is used to diagnose lactose intolerance by measuring the amount of hydrogen in your breath.

Food abstinence test

To find out if a food intolerance or allergy is causing your diarrhea, your doctor may ask you to avoid foods with lactose, carbohydrates, wheat, or other ingredients to see whether your diarrhea is responding to a change in diet.


Your doctor may use an endoscope to look inside your body to help find the cause of your diarrhea. Endoscopic procedures include:

  • Colonoscopy.
  • Flexible sigmoidoscopy.
  • Upper gastrointestinal (GI) endoscopy.

Diarrhea treatment methods

Symptomatic treatment

To address the patient’s discomfort or the parent’s concerns of a child with diarrhea. Some medications that can be used to control diarrhea (stop diarrhea) include:

  • Slow intestinal motility: Loperamide (2mg oral tablet, dose: 2-4mg/day).
  • Drugs to regulate intestinal motility: Trimebutin (oral tablet: 100mg, dose: 100-200mg/day).
  • Drugs that reduce intestinal smooth muscle spasms (reduce abdominal cramps): Drotaverin, Spasmaverin, Buscopan, …

Note: Depending on the condition of loose stools, the patient will be suitable to use one drug, or combine two or more drugs of different groups. However, parents and patients should consult with doctors and pharmacists before taking these drugs. Because in some cases, stopping diarrhea will cause some complications. For example: Necrotizing enterocolitis, sepsis, etc.

You can use Buscopan to relieve stomach cramps

You can use Buscopan to relieve stomach cramps

In addition, depending on the patient’s condition, doctors may combine additional drugs:

  • Antipyretic, analgesic: Paracetamol.
  • Antiemetic: Domperidone, Metochloramide.
  • Zinc syrup, potassium supplements, multi vitamins, …

Advantages: Makes the patient feel better, less uncomfortable, parents of children with diarrhea will have peace of mind and less worry. At the same time limit the risk of children having high fever convulsion.

Cons: Can only treat the symptoms of the disease, ie the top. Failure to treat the root cause of the diarrhea. Excessive symptomatic treatment may mask the silent aggravation of the disease.

Treat the cause

Treatment problem

Treatment of the cause of acute or chronic diarrhea should be performed by specialists in medical facilities. Here, the doctors will examine and take the patient’s medical history and medical history. At the same time, perform some necessary tests such as:

  • Blood count test.
  • Quantification of markers of infection.
  • Blood biochemistry: Liver function, kidney function, electrolytes.
  • Fecal examination, fecal culture…
  • General abdominal ultrasound.
  • Abdominal CT Scan.
  • Gastroscopy, colonoscopy, colonoscopy, etc.

Stool culture is one of the test methods to find the cause of disease

Stool culture is one of the test methods to find the cause of disease

From there, the doctor will determine the specific cause of the diarrhea and have an appropriate treatment for each specific cause.

The treatments

Depending on the cause, doctors may prescribe antibiotics and specific medications to treat bacterial or parasitic infections. Doctors may also prescribe medications to treat certain conditions that cause chronic diarrhea, such as Crohn’s disease, irritable bowel syndrome, or ulcerative colitis. The treatment of diarrhea in children also depends on the cause.

In summary, the most common treatments are:

  • Antibiotics in case of bacterial diarrhea.
  • Antiparasitic drugs in case of parasitic infections.
  • Antiviral when the patient has a viral infection.
  • Surgery in diseases: small bowel cancer, appendicitis, intestinal abscess, …

Advantages: Solving the cause of the disease, it is possible to thoroughly treat diarrhea in patients.

Cons: Complicated, requires high expertise. It should be performed in medical facilities by specialized, experienced doctors. Some cases are quite expensive to treat the cause.

Prevention of diarrhea

We can prevent all kinds of diarrhea: diarrhea caused by infection, environmental change or food.2

Prevention of diarrhea due to infection

You can reduce your risk of getting or spreading infections by washing your hands frequently with soap and warm water for 15 to 30 seconds in the following situations:

  • After going to the toilet, take a shower.
  • After changing diapers for children or the elderly.
  • Before and after handling and processing food.

Parents can also take their children to medical facilities to consult about giving their children some vaccines against viruses and bacteria. Among them, the most popular is the Rota vaccine to prevent diarrhea caused by Rotavirus.

Prevention of diarrhea caused by environmental change

To reduce your risk of getting diarrhea when traveling to new lands, you should:

  • Eat cooked, drink boiled.
  • Use clean, safe, clear-sourced food.
  • Eat prepared foods.
  • Avoid dirty water, unpasteurized dairy products.
  • Limit travel or travel to areas with diarrhea outbreaks.

When traveling to developing countries, you need to choose safe and hygienic food to prevent illness

When traveling to developing countries, you need to choose safe and hygienic food to prevent illness

You can prepare some over-the-counter medications and consult your doctor before traveling.

Prevention of food-borne diarrhea

For this case, you should:

  • Store, cook, clean and handle food properly.
  • Sanitize cooking and food preparation areas more often.
  • Enjoy the food right after it’s done.
  • Refrigerate leftovers properly.
  • Thaw frozen foods before cooking.

Eat cooked food and drink boiling water to prevent diarrhea

Eat cooked food and drink boiling water to prevent diarrhea

Prevention of dehydration caused by diarrhea

Dehydration caused by diarrhea can be prevented by providing the patient with fluids containing electrolytes or cooked drinking water.

In short, this is a very common pathology in our daily lives. The disease can break out into an epidemic and last for a long time, significantly affecting health as well as economy and society. Therefore, each of us needs to be aware of personal hygiene, environmental hygiene, and limit the outbreak of diarrhea. Thereby contributing to protecting the health of themselves, their families and society.

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