Diarrhea

Reviewed by Dr. Nikita Dinger, Founder & CEO, BioMeBar. Last reviewed 7 October 2026.

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What it is

Most of us have had it after a street-food binge or a trip. Diarrhoea is defined as three or more loose or watery stools in a day. Acute diarrhoea lasts less than two weeks and is usually from an infection or something you ate. Persistent diarrhoea runs from two to four weeks, and chronic diarrhoea lasts longer than four weeks and always deserves medical evaluation.

The cause matters more than the label. Infections, lactose intolerance, medicines such as metformin or antibiotics, coeliac disease, inflammatory bowel disease and IBS-D can all look alike on the surface.

Common symptoms

• Loose or watery stools, types 6 and 7 on the Bristol stool chart
• Urgency, or not making it to the toilet in time
• Cramping before passing stool
• Nausea, fever or vomiting if an infection is behind it
• Loose stools that follow meals, especially in the morning
• Tiredness and thirst when fluid is being lost

How gut bacteria may be involved

Gut bacteria form part of the defence against infection, and a settled community makes it harder for pathogens to take hold. Antibiotics can disrupt that community, and antibiotic-associated diarrhoea is a recognised consequence in some people. A small number develop an infection with Clostridioides difficile, which needs medical attention.

After a bout of gastroenteritis, some people continue to have loose stools for weeks or months. Doctors call this post-infectious IBS, and gut bacteria, bile acids and immune activity are all thought to be involved. Read more on the post-infectious IBS page. Probiotics have been studied for acute infectious and antibiotic-associated diarrhoea, with modest benefit for certain strains, but they do not replace fluids.

Bile acids that are not fully reabsorbed can also spill into the colon and loosen stools, which is seen after gallbladder removal or in some people with chronic watery diarrhoea. Bacteria change bile acids as well, so the gut community and bile handling are closely connected.

Diet and everyday habits

For acute diarrhoea, fluid and salt replacement is the first priority. WHO low-osmolarity ORS is the standard, and homemade versions need a correct sugar and salt ratio, so use packet ORS where you can.

• Return to eating early: plain rice, khichdi, curd rice, banana, boiled potato, toast, idli and thin dal water
• Take thin chaas or fresh curd if you tolerate dairy, and skip very sweet drinks and fruit juices
• Avoid very oily, spicy, or raw salad-heavy meals until stools settle
• Limit alcohol, excess coffee and sugar-free sweets with sorbitol
• Wash hands, and be careful with water and cut fruit when travelling

If loose stools keep returning, consider lactose, high-fat meals and caffeine, and look at our IBS diet as a starting point. Soluble fibre from oats, banana or a small dose of psyllium can firm up stool for some people.

Think about what else changed. A new medicine, a large intake of sugar-free sweets, a switch to a protein powder with lactose, a course of antibiotics or a stressful week can each explain loose stools without any infection. Writing down the timeline for the past month often points to the cause quicker than any test.

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When to see a doctor first

• Blood or pus in stool, or black stools
• Signs of dehydration: very dark urine, dizziness, dry mouth, or passing little urine
• High fever, severe abdominal pain or persistent vomiting
• Diarrhoea beyond two to three days in adults or beyond one day in infants, older adults and pregnant women
• Diarrhoea lasting four weeks or more, or waking you from sleep
• Weight loss, anaemia, or a recent hospital stay or antibiotic course

Anti-diarrhoeal tablets are used by many people for short bouts, but they are not suitable when there is blood in the stool or a high fever. A pharmacist or doctor can advise on what suits you.

How BioMeBar approaches it

We do not work with acute infections, and we ask you to see a doctor if you are unwell. For longer-running loose stools that your doctor has assessed, we look at your gut profile and symptom pattern, match a personalised synbiotic, and provide food and lifestyle guidance with check-ins.

We do not diagnose, treat or cure diarrhoea or its causes.

Common questions

Should I stop eating when I have diarrhoea?

Not for long. Fluids come first, but eating bland food early supports recovery and is usually advised over prolonged fasting.

Can I take a probiotic after antibiotics?

Some people do, and certain strains have been studied for antibiotic-associated diarrhoea. Ask your doctor, and keep the dose of the antibiotic and any probiotic spaced apart as advised.

Why do I need the toilet right after eating?

The gastrocolic reflex pushes the colon into action after a meal, and it can be exaggerated in IBS, after gallbladder surgery or with bile acid problems. A doctor can help sort out which is likely.

Is chaas good when you have loose stools?

Many people find thin chaas made from fresh curd comfortable, and it replaces some fluid and salt. If milk products worsen your symptoms, try a smaller amount or leave it for a day or two.

Sources

• WHO recommendations on oral rehydration salts (low-osmolarity formulation)
• ACG Clinical Guideline: Acute Diarrheal Infections in Adults (2016)
• Rome IV criteria for functional diarrhea (Rome Foundation)
• ICMR-NIN Dietary Guidelines for Indians

Talk to us

If you would like to know whether BioMeBar can support you, message us on WhatsApp. Tell us your symptoms and your pincode and we will take it from there. Not sure where to start? Take the free gut assessment, which takes about three minutes.

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BioMeBar provides nutrition and gut health guidance and does not replace medical care. See a doctor for severe, persistent or worrying symptoms.