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Diarrhoea medicine

Diarrhoea medicines (medicines used to relieve diarrhoea symptoms) reduce the number of times that you need to go to the toilet, when you have acute diarrhoea. The most commonly used medicine is loperamide. You can buy this from your local pharmacy or get it on prescription from your doctor. Most people only need to take these medicines for a few days and they are not needed for every diarrhoeal illness. Children under the age of 12 years should not take diarrhoea medicines unless their doctor has told them to do so.

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What is diarrhoea medicine?

Diarrhoea medicine is used to reduce the number of trips that you need to make to the toilet when you have diarrhoea. Two main types of diarrhoea medicines are used to treat diarrhoea. These are called antimotility medicines and bulk-forming agents:

Antimotility medicines

This type of diarrhoea medicine is used to treat acute diarrhoea. They include:

  • Codeine phosphate.

  • Co-phenotrope.

  • Loperamide.

  • Kaolin and morphine mixture.

The most commonly used antimotility medicine is loperamide (Imodium®). Kaolin and morphine mixture is very rarely used to treat diarrhoea nowadays. Antimotility medicines are generally not advised for children under the age of 12 and is only available to buy over the counter for those aged 12 or over.

Fluid replacement

It is important to remember that diarrhoea medicines are not the only treatments used for diarrhoea. The most important treatment is fluid replacement. See separate leaflets called Acute Diarrhoea in Children, and Diarrhoea.

The rest of this leaflet deals only with antimotility medicines when they are used to ease the symptoms of acute diarrhoea. For information on bulk-forming agents, see separate leaflet called Irritable Bowel Syndrome.

How do antimotility diarrhoea medicines work?

Antimotility medicines work by slowing down the movement of your gut, which reduces the speed at which the contents pass through. Food remains in your gut for longer and this allows more water to be absorbed back into your body. This results in firmer stools that are passed less often.

Antimotility medicines reduce the number of times you need to go to the toilet. This can be helpful in allowing you to continue your normal activities, or if you need to travel anywhere. However, there is no convincing evidence that they reduce the duration of the diarrhoea. Most cases of acute diarrhoea get better on their own in exactly the same amount of time, whether you take any medicines or not.

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Which antimotility medicines are normally used to treat acute diarrhoea?

Loperamide is the most commonly used antimotility medicine for acute diarrhoea. It is thought to be the safest and most effective antimotility medicine. Co-phenotrope and codeine are used much less often than loperamide.

As discussed above, kaolin and morphine mixture is an older treatment for acute diarrhoea and is very rarely used nowadays.

When should I take an antimotility diarrhoea medicine?

For most adults and children older than 12 years, antimotility medicines are usually not necessary when they have a bout of diarrhoea. However, some people may wish to reduce the number of trips that they need to make to the toilet. For example, if you have to make an essential journey, taking antimotility medicines may help to make this possible.

Children should not be given antimotility medicines. This is because some children have had very serious side-effects after they have taken these medicines.

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How should I take antimotility diarrhoea medicines?

The following directions are for adults only:

Loperamide - the adult dose of this is two capsules at first. This is followed by one capsule after each time you pass some diarrhoea, up to a maximum of eight capsules in 24 hours.

Co-phenotrope - the adult dose is four tablets at first. Six hours later, take two more tablets. After that, take two tablets every six hours.

Codeine phosphate - for adults, the usual dose is one 15 mg tablet, up to four times a day.

What is the usual length of treatment?

Most people only need to take an antimotility medicine for a few days. In general, you should not take these medicines for longer than five days unless your doctor has told you to do so.

Where can I buy diarrhoea medicine?

You can buy loperamide and co-phenotrope from your local pharmacy. You can also obtain both of these medicines from your doctor, on prescription. Codeine phosphate is only available from your doctor, on a prescription.

You can only buy kaolin and morphine mixture from your local pharmacy, but quite a few pharmacies do not keep this medicine any more.

Antisecretory medicines are only available from your doctor, on prescription.

Diarrhoea medicine side-effects

The most commonly reported adverse effects of antimotility diarrhoea medicines are:

Rare symptoms you may experience are:

Some children have very serious side-effects after they have taken these medicines - for example:

  • A condition where part of the gut dies (necrotising enterocolitis).

  • Confusion.

  • Depressed breathing.

  • Coma.

Some children have died after taking these medicines - this is very rare. However, this is why these medicines are not recommended for children.

For a full list of side-effects see the leaflet that comes with your medicine.

Who cannot take diarrhoea medicines?

You should not take diarrhoea medicine if:

What is acute diarrhoea?

Diarrhoea is the passing of frequent loose or liquid stools (faeces). When this change to the stools starts suddenly and lasts for less than two weeks, the condition is known as acute diarrhoea. If it lasts more than two weeks, it is called persistent diarrhoea. If it lasts more than four weeks it is called chronic diarrhoea. There are a number of causes of acute diarrhoea:

  • Infection of the gut is the common cause. This is called acute infectious diarrhoea. Many bacteria, viruses and other germs can cause diarrhoea. Sometimes the germs come from infected food (food poisoning). Infected water is a cause in some countries. Sometimes it is just 'one of those germs going about'. Viruses are easily spread from one person to another by close contact, or when an infected person prepares food for others.

  • Other causes are uncommon and include side-effects from some medicines, food allergy and anxiety.

  • Gut disorders that cause chronic diarrhoea may be mistaken for acute diarrhoea when they first begin - for example, diarrhoea caused by ulcerative colitis.

Usually no treatment is required when you have acute diarrhoea, other than drinking plenty of fluids.

See the separate leaflets called Diarrhoea and Acute Diarrhoea in Children.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 24 Mar 2028
  • 26 Mar 2023 | Latest version

    Last updated by

    Dr Toni Hazell

    Peer reviewed by

    Dr Colin Tidy, MRCGP
  • 20 Apr 2012 | Originally published

    Authored by:

    Jenny Whitehall
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