Diarrhea

Diarrhea means having loose or watery stools, usually three or more times a day or more often than is normal for you. It is a symptom rather than a disease.

Many cases are caused by a short-lived infection and improve within a few days. Diarrhea can also result from medication, food intolerance, or a longer-term bowel condition.

The main immediate concern is dehydration—losing more water and body salts than you replace. Babies, older adults, and people with serious health conditions can become dehydrated more quickly.

Diarrhea lasting four weeks or longer is called chronic diarrhea. Persistent or recurring symptoms need medical assessment.

Stools may be soft, mushy, or completely watery. You may need to reach a toilet quickly or have less control than usual.

Other symptoms can include:

• Belly cramps, bloating, nausea, or vomiting
• Fever or chills during an infection
• Mucus in the stool
• Soreness around the anus
• Tiredness, thirst, dizziness, or reduced urination from fluid loss

Green or yellow stool can occur when material moves quickly through the bowel and is not usually concerning by itself.

Visible red blood or black, sticky, tar-like stool needs prompt medical attention. Iron tablets and medicines containing bismuth can darken stool, but unexplained black stool should still be assessed.

Common causes include viral gastroenteritis, or a stomach bug, and food poisoning from contaminated food or water. Infection can spread through unwashed hands, shared surfaces, or close contact.

Medicines that may cause diarrhea include antibiotics like amoxicillin or doxycycline, laxatives, magnesium-containing products, and some diabetes medicines. Do not stop a prescribed medicine without speaking with a healthcare professional.

Large amounts of alcohol, caffeine, artificial sweeteners, or fatty food may loosen stools. Lactose intolerance can cause diarrhea, gas, and bloating after dairy products.

Less common causes include irritable bowel syndrome, coeliac disease, inflammatory bowel disease, poor nutrient absorption, and problems involving the pancreas or bile acids. These are more likely when diarrhea returns or lasts for weeks.

Causes needing urgent assessment include severe bowel infections, inflammation, or reduced blood flow in the bowel. These may cause bloody stool, intense or constant pain, high fever, or marked weakness. Symptoms alone cannot identify the cause.

Seek same-day medical care if you have:

• Blood in the stool or black, tar-like stool
• Severe, worsening, or constant belly pain
• Frequent vomiting that prevents you from drinking
• A high fever or rapidly worsening illness
• Signs of dehydration, such as a very dry mouth, dizziness, or much less urine
• Frequent diarrhea during or soon after antibiotic treatment

Call emergency services if you faint, become confused or difficult to wake, have severe weakness, or have signs of severe dehydration with little or no urine.

Arrange a routine appointment if diarrhea is not starting to improve after several days, lasts for weeks, keeps returning, wakes you at night, or comes with unexplained weight loss. Seek advice sooner for a baby, an older or frail person, during pregnancy, or if your immune system is weakened.

A healthcare professional will ask when the diarrhea started and whether there is blood, fever, pain, vomiting, or weight loss. They may ask about recent food, travel, untreated water, illness in close contacts, and new medicines or antibiotics. An examination can check for dehydration and abdominal tenderness.

Short-lived, mild diarrhea often does not require testing. If symptoms are severe, bloody, prolonged, or linked to travel or antibiotics, a stool sample may be tested for bacteria, parasites, blood, or inflammation. Blood tests can assess dehydration and look for conditions such as coeliac disease. Persistent symptoms may require imaging or a colonoscopy, which uses a small camera to examine the large bowel.

Replacing lost fluid is the main treatment. Take frequent small sips if nausea makes drinking difficult. Oral rehydration solution provides a measured balance of water, sugar, and salts and can be especially helpful after repeated watery stools or vomiting.

Continue breastfeeding a baby with diarrhea. Children and people at higher risk of dehydration should receive individual medical advice. Very sugary drinks may worsen diarrhea and do not have the same balance as oral rehydration solution.

Eat when you feel able. Small portions of familiar foods may be easier to manage. There is usually no need to fast or follow a highly restricted diet. Limit alcohol, caffeine, and foods that clearly worsen symptoms.

Some non-prescription anti-diarrheal medicines may reduce watery diarrhea in adults. Ask a pharmacist whether one is suitable. Do not use them for bloody diarrhea or diarrhea with a high fever unless a healthcare professional advises it. Children should not receive them without professional guidance.

Antibiotics do not treat viral diarrhea and are useful only for certain bacterial or parasitic infections. Do not take leftover antibiotics.

Wash your hands with soap and water after using the toilet and before handling food. Avoid preparing food for others while unwell. Gently clean and dry sore skin around the anus; a barrier cream may reduce irritation.

Diarrhea from a short-lived infection often begins improving within a few days. Appetite and bowel habits may take longer to return to normal.

Get medical advice if recovery stalls or symptoms return. Ongoing diarrhea may require tests and treatment for its cause. A brief record of stool frequency, foods, medicines, travel, and other symptoms can help at an appointment.

Is diarrhea contagious?

Diarrhea itself is not contagious, but many infections that cause it are. Careful handwashing and not sharing towels can reduce spread.

Should I avoid all dairy products?

Not always. Some people temporarily digest lactose poorly after a bowel infection. If dairy clearly worsens symptoms, reducing it briefly may help.

Can stress cause diarrhea?

Yes. Stress can speed bowel movement and worsen conditions such as irritable bowel syndrome. New or persistent diarrhea should not automatically be attributed to stress.

Does stool color reveal the cause?

Usually not by itself. Food, medicines, and rapid movement through the bowel can change color. Blood or unexplained black, tar-like stool is more important than green or yellow stool.