Antispasmodic Medicines

What are antispasmodics?

Antispasmodics are a class (group) of medicines that can help to control some symptoms that arise from the gut – in particular, gut spasm.

There are two main types:

  • Antimuscarinics such as dicycloverine, hyoscine, atropine, propantheline.
  • Smooth muscle relaxants such as alverine, mebeverine and peppermint oil.

How do antispasmodics work?

Your gut is partially controlled by an extensive network of neurons (cells of the nervous system). These help to regulate the motility (movement) of the gut. The neurons work by controlling smooth muscle which is present in the walls of the gut. It is this muscle which is responsible for gut movements.

The neurons are stimulated by various different chemicals produced by your body. These chemicals work by binding to special receptors (docking sites) on the muscle surface, which causes either relaxation or contraction (spasm) of the smooth muscle. Contractions of the smooth muscle cause food in the gut to be moved further along the gut. However, in conditions such as irritable bowel syndrome (IBS) these contractions can occur too often or be painful, causing some of the symptoms of IBS.

Antimuscarinics work by blocking muscarinic receptors. These are a class of receptors found in the gut, which cause muscle contraction as described above. Blocking the receptors reduces the amount of contractions and should help to relieve some of the symptoms associated with IBS.

Because muscarinic receptors are also found in other parts of the body, taking an antimuscarinic can have other effects. For example, muscarinic receptors also help to control the production of saliva in the mouth. Taking a medicine that blocks these receptors may cause a dry mouth.

Smooth muscle relaxants work directly on the smooth muscle in the wall of the gut. Here they help to relax the muscle and relieve the pain associated with a contraction of the gut.

What conditions are they used to treat?

Antispasmodics are commonly used in IBS:

  • To help relieve some of the symptoms of IBS such as spasm (colic), bloating and abdominal (stomach) pain.
  • To reduce the motility (movement) of the intestines (gut).

Note: not everybody with IBS finds that antispasmodics work well. However, they are worth trying, as they work well in a good number of cases.

Antispasmodics are also used in some other conditions such as diverticular disease.

Which is the best one?

Overall, medical studies do not suggest one antispasmodic is more effective at relieving symptoms than another. However, some people seem to respond better to one type rather than another. Therefore, if one does not work so well, it is worth trying a different one.

How do I take antispasmodics?

Your doctor will advise you how to take your medication, including how often. You may be encouraged to use the medicine at a particular time in relation to eating. Some people take a dose before meals if pains tend to develop after eating.

It is generally recommended that you take these medicines only when necessary. For example, people with IBS commonly find that there are times when symptoms flare up for a while. So, it is common to take an antispasmodic when symptoms flare up, and to stop them if symptoms settle down.

Note: pains may ease with medication but may not go away completely.

How quickly do antispasmodics work?

Antispasmodics usually work within an hour or so to ease symptoms. Their effectiveness may depend on the dose you are given and how often you take them.

How long is treatment needed?

These medicines are usually only used when you have active symptoms. However, this can vary depending on the reason for treating you. Your doctor should be able to advise you on this.

Other considerations

If you have IBS you may become used to having gut symptoms. However, do not assume all gut symptoms are due to your IBS. You should consult your doctor if you experience any change in the usual pattern of your symptoms. In particular, the following problems can indicate a serious gut disorder:

  • Unintentional weight loss.
  • Bleeding from the rectum (back passage).
  • Blood in your stools (this may colour your stools (faeces) black).

Who cannot take antispasmodics?

Most people can take antispasmodics. There are a few exceptions. A full list of people who should not take antispasmodics is included with the information leaflet that comes with the medicine packet.

If you are prescribed antispasmodics, read this to be sure you are safe to take it. In particular, antispasmodics may not be suitable for people with paralytic ileus (paralysis of the gut muscles), myasthenia gravis (a condition causing muscle weakness), pyloric stenosis (narrowing of the outlet from the stomach) and prostatic enlargement. Pregnant or breast-feeding mothers should also seek advice before using these medicines.

Can I buy antispasmodic medicines?

You can buy some antispasmodics from your pharmacist. However, most are only available with a prescription.

What are the possible side-effects?

Most people who take antispasmodics do not have any serious side-effects. If side-effects occur, they are usually minor. The most common side-effects are:

  • Flatulence and bloating (wind)
  • Heartburn
  • Constipation
  • Dry mouth

Note: the above is not the full list of side-effects for these medicines. Please see the leaflet that comes with your particular brand for full list of possible side-effects and cautions.

These medicines sometimes react with other medicines that you may take. So, make sure your doctor knows of any other medicines that you are taking, including ones that you have bought rather than been prescribed.

How to use the Yellow Card Scheme

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at the following web address: http://yellowcard.mhra.gov.uk

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that your medicines may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • Information about the person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication and/or the leaflet that came with it with you while you fill out the report.

Further help and information

The IBS Network

Unit 5, 53 Mowbray Street, Sheffield, S3 8EN
Tel: 0114 272 32 53 Web: www.theibsnetwork.org
Offers advice, information and support for people with IBS

References and Disclaimer | Provide feedback


  • British National Formulary; 62nd Edition (Sep 2011) British Medical Association and Royal Pharmaceutical Society of Great Britain, London (link to current BNF)
  • Irritable bowel syndrome, Prodigy (August 2008)
  • Irritable bowel syndrome, NICE Clinical Guideline (February 2008); Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care


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