Diarrhoea

Diarrhoea is one of the most common health problems affecting people of all ages worldwide. While usually mild and temporary, lasting only a few days, it can sometimes signal a more serious condition requiring medical attention. Understanding its causes, recognizing warning signs, and knowing how to manage symptoms can help prevent complications like dehydration.

Table of contents

• What is diarrhoea?
• Types of diarrhoea
• What causes diarrhoea?
• Symptoms
• Who is more likely to have diarrhoea?
• Complications
• When to see a doctor
• Diagnosis
• Treatment
• Prevention

What is diarrhoea?

Diarrhoea is characterized by loose, watery stools that occur three or more times per day, or more frequently than is normal for you^[1]. The condition means having bowel movements with decreased stool consistency^[2]. It is important to note that frequent passing of formed stools is not diarrhoea, nor is the passing of loose, pasty stools by breastfed babies^[1].

Diarrhoea happens when not enough water is removed from your stool, or too much fluid is secreted into the stool, making it loose^[12]. When the cells in your small intestine or colon are irritated, the relaxed and regular movement of your intestines can become overactive. Essential salts and fluids, as well as nutrients from the food that you eat, end up being passed through the colon too quickly. With less fluid being absorbed by the body, the result is loose or watery stools^[4].

Types of diarrhoea

Diarrhoea is classified into different types based on how long it lasts^[2][3]:

Acute diarrhoea is the most common type. It is a short-term condition that typically lasts less than a week, usually one or two days, and goes away on its own without treatment^[2][3]. Some sources define acute diarrhoea as lasting less than 14 days^[4].

Persistent diarrhoea lasts longer than 2 weeks but less than 4 weeks^[2][4].

Chronic diarrhoea lasts at least 4 weeks^[2]. Chronic diarrhoea symptoms may be ongoing or may come and go over a long period^[3]. Diarrhoea that lasts this long may indicate a more serious condition that warrants a visit with your healthcare provider^[9].

Diarrhoea can also be classified by severity based on the number of stools and their size^[4][8]:

• Severe diarrhoea means having more than 10 loose, watery stools in a single day (24 hours)
• Moderate diarrhoea means having more than a few but not more than 10 diarrhoea stools in a day
• Mild diarrhoea means having only a few loose and watery stools in a day

What causes diarrhoea?

Diarrhoea usually results from an infection in the intestinal tract, which can be caused by a variety of bacterial, viral, and parasitic organisms^[1]. However, there are many different causes.

Infections are among the most common causes. The main cause of diarrhoea is a virus that infects your gut, a condition called gastroenteritis (sometimes referred to as “stomach flu” or a “stomach bug”)^[9]. The most common cause of diarrhoea in adults is the norovirus, while rotavirus is the most common cause of acute diarrhoea in children^[3][9]. Bacteria from contaminated food or water and parasites can also cause infections leading to diarrhoea^[3].

Food poisoning occurs when you ingest harmful toxins and pathogens from contaminated foods or drinks. Once they’re in your gut, the toxins or germs can cause diarrhoea^[9]. “Traveler’s diarrhoea” happens when you get diarrhoea while traveling in a new environment with poor hygiene or sanitation, usually due to exposure to bacteria^[9].

Medications can trigger diarrhoea as a common side effect^[3]. For example, antibiotics kill harmful bacteria that make you sick, but they can destroy helpful bacteria in the process, and not having enough good bacteria can lead to diarrhoea^[9]. Diarrhoea is also a side effect of antacids with magnesium and some cancer drugs and treatments. Overusing laxatives can also cause diarrhoea^[9].

Foods that upset your digestive system can cause diarrhoea. If you’re lactose intolerant, you get diarrhoea because your body struggles to digest lactose (the sugar in dairy)^[9]. Some people have trouble digesting fructose, a sugar in honey and fruits that’s added as a sweetener to some foods. With celiac disease, you get diarrhoea because your body has trouble breaking down gluten, a protein in wheat^[9].

Diseases affecting your bowels are common causes of chronic diarrhoea. Diarrhoea is a common symptom of conditions that cause irritation and inflammation in your bowels (intestines)^[9]. These include:

• Inflammatory bowel disease, including Crohn’s disease and ulcerative colitis^[3][6]
• Irritable bowel syndrome (IBS), a functional disorder^[3][5]
• Microscopic colitis, a persistent type of diarrhoea that often affects older adults^[5]

Procedures on your bowels can lead to diarrhoea. Many people have diarrhoea after surgery on their bowels, as it may take a while for the digestive tract to absorb water and nutrients properly again^[9].

Other causes include endocrine disorders such as Addison’s disease and carcinoid tumors, as well as certain gut cancers^[5].

Symptoms

The primary symptom of diarrhoea is passing loose, watery stools three or more times a day. Beyond this main symptom, you may experience^[3][12]:

• Nausea (feeling sick) and vomiting (being sick)
• Fever
• Headache
• Bloating
• Flatulence (excess gas)
• Abdominal pain or cramping (tummy pain)
• Loss of appetite
• An urgent need to use the toilet

If a virus or bacteria is the cause of your diarrhoea, you may also have a fever, chills, and bloody stools^[3].

Who is more likely to have diarrhoea?

Diarrhoea affects people of all ages. Most adults get acute diarrhoea once a year, while children tend to get it twice a year^[9]. Young children have it an average of twice a year^[3].

You’re more likely to have diarrhoea if you^[2]:

• Have a viral or bacterial infection
• Were exposed to untreated water, such as while camping or traveling to countries with limited sanitation
• Work in a hospital, nursing home, or daycare facility
• Have food allergies or digestive tract problems
• Take certain medicines, such as antibiotics or medicines commonly used to treat cancer
• Consume food or drinks with sugar alcohols, such as sorbitol, mannitol, or xylitol

People who visit developing countries are at risk for traveler’s diarrhoea, caused by consuming contaminated food or water^[3].

Children who are malnourished or have impaired immunity, as well as people living with HIV, are most at risk of life-threatening diarrhoea^[1].

Complications

Diarrhoea can lead to serious complications, particularly dehydration and malabsorption^[2].

Dehydration

Dehydration means your body doesn’t have enough fluid and electrolytes. Diarrhoea, especially acute diarrhoea, may cause you to become dehydrated because loose stools remove more fluid and electrolytes from your body than solid stools^[2]. You can lose a lot of fluid if you have diarrhoea, so it’s important to replace the fluid to prevent dehydration^[12].

Dehydration can develop when you have diarrhoea, especially in children and older adults^[12]. People who have diarrhoea and are pregnant, are over age 65, are currently taking antibiotics, or have a weakened immune system are more likely to have complications from diarrhoea^[2].

Signs of dehydration include^[6]:

• Dry and sticky mouth
• No urine for six hours
• No tears when crying
• Sunken eyes

If you can’t drink enough liquids or oral rehydration solutions to rehydrate your body, becoming dehydrated can lead to serious health problems, such as organ damage, shock, coma, or even death. However, serious health problems from being dehydrated are rare^[2].

Malabsorption

Malabsorption occurs when your body can’t absorb enough nutrients from the food you eat. Diarrhoea is a leading cause of malnutrition in children under 5 years old^[1]. Chronic or persistent diarrhoea can lead to malnutrition, abdominal pain, and weight loss^[4].

When to see a doctor

Although diarrhoea is usually not harmful, it can become dangerous or signal a more serious problem. Contact your healthcare provider if you have^[3][6]:

• Signs of dehydration
• Diarrhea for more than 2 days if you are an adult, or more than 24 hours for children
• Severe pain in your abdomen or rectum
• A fever of 102 degrees Fahrenheit or higher
• Stools containing blood or pus
• Stools that are black and tarry
• Blood, mucus, or pus in the stool
• More than eight stools in eight hours
• Vomiting that continues for more than 24 hours
• Stomach pain or abdominal cramping
• Diarrhea that develops within one week of travel outside of the United States or after a camping trip

If your newborn (under 3 months old) has diarrhoea, you should call your doctor immediately^[6]. If children have diarrhoea, parents or caregivers should not hesitate to call a healthcare provider, as diarrhoea can be especially dangerous in newborns and infants^[3].

Diagnosis

To find the cause of diarrhoea, your healthcare professional will likely ask about your medical history, review the medicines you take, and conduct a physical exam^[10]. A thorough travel and dietary history can help guide the clinician toward an appropriate workup for infections or food intolerance^[7].

Most patients do not require laboratory workup, and routine stool cultures are not recommended^[13]. Diagnostic investigation should be reserved for patients with severe dehydration or illness, persistent fever, bloody stool, or immunosuppression, and for cases of suspected nosocomial infection or outbreak^[13].

Your healthcare provider may order tests to determine what’s causing your diarrhoea. Possible tests include^[3][10]:

• Blood tests: A complete blood count, measurement of electrolytes, and tests of kidney function can help indicate how severe your diarrhoea is
• Stool test: You may have a stool test to see if a bacterium or parasite is causing your diarrhoea
• Hydrogen breath test: This type of test can help determine if you have a lactose intolerance
• Flexible sigmoidoscopy or colonoscopy: Using a thin, lighted tube that’s inserted into the rectum, a medical professional can see inside of the colon
• Upper endoscopy: A medical professional uses a long, thin tube with a camera on the end to examine the stomach and upper small intestine

Treatment

Most cases of sudden diarrhoea clear on their own within a couple of days without treatment^[10]. In most cases, you can treat acute diarrhoea at home without medical treatment^[11]. Treatment focuses on preventing and treating dehydration^[13].

Hydration and rehydration

When you have diarrhoea, you need to replace lost fluids and electrolytes to stay hydrated. Drink plenty of water and liquids that contain electrolytes, such as broths and sports drinks^[11]. Clear fluids are likely to be better tolerated, such as fruit squashes, cordials, tea, decaffeinated coffee, clear soups, or rehydration drinks^[22].

Oral rehydration solution (ORS) is particularly effective. You can also drink oral rehydration solutions, liquids that contain glucose and electrolytes. You can make rehydration solutions at home or buy them from a store that sells medicines or baby supplies^[11]. The small intestine absorbs the solution to replace the water and electrolytes lost in the stool^[1].

For children, it’s important that they stay hydrated when they have diarrhoea. They should drink plenty of water, as well as oral rehydration solutions, broths, and sports drinks. Infants should drink breast milk or formula as usual^[11].

If you are severely dehydrated, your doctor may recommend you receive intravenous (IV) fluids. Doctors may need to treat people with severe dehydration in a hospital^[11].

Diet and nutrition

When your appetite returns, you can most often go back to eating your normal diet, even if you still have diarrhoea^[11]. However, certain dietary approaches may help relieve symptoms.

The BRAT diet may help. BRAT stands for bananas, rice, applesauce, and toast^[14]. These foods are bland, starchy, and low in fiber, which may help firm up your stool. Other similarly bland foods include saltine crackers, clear broth, rice water, and potatoes^[4]. The BRAT diet shouldn’t be followed for more than 2 days because it doesn’t provide a balanced, nutritious diet^[4].

Tips for managing your diet include^[19][22]:

• Eat smaller meals and more snacks
• Avoid food or drinks containing artificial sweeteners such as sorbitol, mannitol, or xylitol, which can make diarrhoea worse
• Try not to eat too much greasy, fatty, or spicy food
• Avoid high fiber foods temporarily
• Choose soft, easily digested foods
• Choose low fiber varieties of food, such as white bread, white pasta and rice

Antidiarrheal medicines

In most cases, you can safely treat acute diarrhoea with over-the-counter medicines such as loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol)^[11]. Loperamide is an antimotility drug that reduces stool passage. Bismuth subsalicylate reduces diarrheal stool output in adults and children^[5].

Doctors typically recommend against over-the-counter medicines for infants, children, or people who have bloody stools or fever. See a doctor if your diarrhoea gets worse or lasts more than 2 days while taking over-the-counter medicine^[11]. Antimotility agents should be avoided in patients with bloody diarrhoea^[13].

Probiotics

Probiotics are sources of “good” bacteria that work in your intestinal tract to create a healthy gut environment^[23]. Probiotic use may shorten the duration of illness^[13]. Probiotics come in powder or pill form, and are also found in foods such as yogurt and kefir^[4].

Antibiotics and other medications

Antibiotics or antiparasitic medicines might help treat diarrhoea caused by certain bacteria or parasites^[10]. When used appropriately, antibiotics are effective in the treatment of shigellosis, campylobacteriosis, Clostridium difficile, traveler’s diarrhoea, and protozoal infections^[13]. Antibiotics can only treat diarrhoea due to bacterial infections^[5].

Prevention

A significant proportion of diarrhoeal disease can be prevented through safe drinking-water and adequate sanitation and hygiene^[1]. Infection is spread through contaminated food or drinking-water, or from person-to-person as a result of poor hygiene^[1].

Prevention of acute diarrhoea is promoted through^[13]:

• Adequate hand washing
• Safe food preparation
• Access to clean water
• Vaccinations

Interventions to prevent diarrhoea, including safe drinking-water, use of improved sanitation, and hand washing with soap, can reduce disease risk^[1].