Diarrhoea in Adults: Causes, ORS, Diet and Warning Signs

6 min read · Conditions · By the Asthra Health Care team

What is diarrhoea?

Diarrhoea means passing loose or watery stools three or more times a day. Short-term (acute) diarrhoea usually lasts less than two weeks and is most often caused by an infection. Diarrhoea lasting more than four weeks is called chronic and needs a doctor's evaluation.

In India, diarrhoea is more common in the summer and monsoon, when food spoils faster and drinking water is more likely to be contaminated. It often comes with stomach cramps, nausea, bloating or vomiting, and sometimes fever. Most adults recover within a few days.

Common causes of diarrhoea in adults

Most cases are caused by viruses, bacteria or parasites from contaminated food or water. Other causes include food poisoning, some medicines such as antibiotics, too much alcohol, food intolerance such as lactose intolerance, and long-term conditions like irritable bowel syndrome, inflammatory bowel disease or thyroid problems.

• Viruses such as norovirus or rotavirus
• Bacteria such as E. coli, Salmonella, Shigella or cholera
• Parasites such as Giardia or amoeba
• Medicines, especially antibiotics
• Food intolerance or long-term gut conditions

Signs of dehydration

The main risk of diarrhoea is losing too much water and salts from the body. Watch for thirst, dry mouth, passing less urine or dark yellow urine, dizziness on standing, tiredness and headache. Severe dehydration causes confusion, fast heartbeat, sunken eyes and very little urine.

Elderly people, pregnant women and people with diabetes, kidney disease or heart disease become dehydrated faster and should seek help early. People taking medicines for blood pressure, diabetes or water tablets should ask their doctor whether any need to be paused while they are unwell; do not change them on your own.

ORS and fluids

Oral rehydration solution (ORS) is the most important treatment. It contains the right balance of salts and sugar to help the body absorb water. Mix one packet exactly as directed in clean drinking water, and sip it frequently, especially after each loose stool. Prepared ORS should be used within a day.

Other helpful fluids include plain water, rice water (kanji), buttermilk, tender coconut water and clear soups. Avoid sugary soft drinks, packaged fruit juices and energy drinks, which can make diarrhoea worse. Limit tea, coffee and alcohol. Take small sips often if you feel sick, rather than drinking a large glass at once.

What to eat

Keep eating small, light meals. Good choices include rice, curd rice, idli, khichdi, bananas, boiled potatoes, toast and dal water. Curd may help some people. Avoid oily, spicy and heavy food, and raw salads, until you feel better. Most people can return to their usual diet within a few days.

Some people find that milk and milk products upset the stomach for a few days after diarrhoea, because the gut takes time to recover. If this happens, reduce milk for a short while and use curd or buttermilk instead. Breastfeeding mothers should continue breastfeeding their babies and drink extra fluids themselves.

Medicines and tests

Most adult diarrhoea does not need antibiotics. Zinc is mainly recommended for children. Anti-diarrhoeal medicines such as loperamide can reduce the number of stools in adults with mild watery diarrhoea, but should not be used if there is blood in stools or high fever; follow the label or your pharmacist's advice. Do not give them to children.

If diarrhoea is severe, bloody, or lasts more than a few days, a doctor may test the stool and blood, and may prescribe antibiotics or antiparasitic medicine. These are used only on a doctor's prescription. Taking antibiotics on your own can cause side effects, change the gut bacteria and make it harder to find the real cause.

Prevention and when to see a doctor

Drink boiled or purified water, wash hands with soap before eating and after using the toilet, and eat freshly cooked food. Keep cooked food covered and refrigerated, and avoid cut fruits and street food in the hot and rainy months.

See a doctor if diarrhoea lasts more than two to three days, or if you notice any warning signs listed below. Diarrhoea that keeps returning, or comes with weight loss, needs a proper check-up to look for long-term causes. Your doctor or pharmacist can help you choose safe treatment.

This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.