Digestive
Medicines for Acute diarrhoea
A sudden bout of loose or watery stools — usually caused by a passing viral infection and getting better on its own, where the main priority is staying well hydrated rather than reaching for anti-diarrhoeal medicine.
Education and reference only. This explains which medicines are used and why, in plain language — it deliberately contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician, and check the BNF and the product labelling for prescribing detail.
Quick answer
What is Acute diarrhoea?
Acute diarrhoea means passing looser or more frequent stools than usual for a short period, often alongside tummy cramps, nausea or a mild fever. In most cases it is caused by a viral infection of the gut (gastroenteritis), although it can also follow food poisoning, a course of antibiotics or recent travel.
- How it is treated: The cornerstone of treatment is rehydration — replacing the fluid and salts lost in the stools, ideally with an oral rehydration solution and by sipping fluids regularly rather than gulping large amounts.
- Self-care: Sip fluids steadily to stay hydrated, wash hands thoroughly to avoid spreading infection, and ease back to normal eating as your appetite returns.
- When to seek help: Seek medical advice if there are signs of dehydration (such as dizziness, very little urine or a dry mouth), blood or mucus in the stools, severe or persistent tummy pain, a high fever, symptoms lasting longer than a few days, or if diarrhoea follows recent travel or a course of antibiotics.
What it is
Acute diarrhoea means passing looser or more frequent stools than usual for a short period, often alongside tummy cramps, nausea or a mild fever. In most cases it is caused by a viral infection of the gut (gastroenteritis), although it can also follow food poisoning, a course of antibiotics or recent travel. It is unpleasant but usually self-limiting, settling within a few days as the body clears the infection. The main risk is losing too much fluid and salts, which matters most in very young children, older people and anyone who is already unwell. Because most episodes are not caused by anything that an antibiotic would help, the focus of care is on keeping the body topped up with fluid while the bout runs its course.
How it is treated
The cornerstone of treatment is rehydration — replacing the fluid and salts lost in the stools, ideally with an oral rehydration solution and by sipping fluids regularly rather than gulping large amounts. Eating can usually continue as appetite allows. Anti-diarrhoeal medicine is not needed for most people and does not treat the underlying cause, but in otherwise well adults it can be used for a short time to ease the symptoms when an urgent need to control symptoms makes life difficult. It is best avoided where there is blood in the stool or a high fever, because these can signal a more invasive infection that should not be slowed down, and it is not suitable for young children. If diarrhoea follows recent antibiotics, persists, or comes with worrying features, medical advice should be sought rather than simply suppressing the symptom.
For this condition, these medicines
Medicine classes used for Acute diarrhoea
Each links to a full, dose-free guide — what it is, how it works, who can and cannot use it, side effects, interactions and FAQs.
Symptom checker
Symptoms that can point to Acute diarrhoea
Acute diarrhoea can be one cause of these symptoms. Each guide explains the other possible causes and the red-flag warning signs that mean you should get urgent help:
Beyond medication
Lifestyle and self-care
Sip fluids steadily to stay hydrated, wash hands thoroughly to avoid spreading infection, and ease back to normal eating as your appetite returns.
When to get help
When to see a doctor
Seek medical advice if there are signs of dehydration (such as dizziness, very little urine or a dry mouth), blood or mucus in the stools, severe or persistent tummy pain, a high fever, symptoms lasting longer than a few days, or if diarrhoea follows recent travel or a course of antibiotics. Diarrhoea in a baby, a frail older person or anyone who cannot keep fluids down needs prompter attention.
Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.
Answers
Acute diarrhoea: frequently asked questions
What medicines are used for acute diarrhoea?
For most people, no medicine is needed — the priority is rehydration with oral rehydration solution and regular fluids. In otherwise well adults, an anti-diarrhoeal can be used for a short time to ease symptoms, but it does not treat the cause and should be avoided if there is blood in the stool or a high fever, and it is not suitable for young children.
Should I take something to stop the diarrhoea?
Often it is better not to. Diarrhoea is partly how the body clears an infection, so stopping it is not always helpful and can occasionally do harm. Concentrate on staying hydrated and let the bout settle; reach for an anti-diarrhoeal only as short-term relief in an adult, and not if you have blood in the stool or a high fever.
How can I avoid getting dehydrated?
Sip fluids little and often rather than drinking large amounts at once, and use an oral rehydration solution to replace lost salts as well as water. Watch for signs of dehydration such as dizziness, a dry mouth or passing very little urine, and seek help if these appear or you cannot keep fluids down.
When does diarrhoea need a doctor?
Contact a healthcare professional if you see blood or mucus, have severe tummy pain or a high fever, become dehydrated, have symptoms lasting more than a few days, or if the diarrhoea started after recent travel or antibiotics. Babies, frail older people and anyone unable to keep fluids down should be assessed sooner.
Sources
Where this is drawn from
- NICE CKS: Diarrhoea — adult's assessment.
- NICE CKS: Diarrhoea and vomiting.
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