Antispasmodic medicines are used to treat symptoms such as tummy pain and cramp (spasm). They are most often used for symptoms of irritable bowel syndrome. The side-effects that may occur are usually minor.
What are antispasmodics?
Antispasmodics are a group (class) of medicines that can help to control some symptoms that arise from the gut (intestines) - in particular, gut spasm.
There are two main types, as follows.
Antimuscarinics such as:
Smooth muscle relaxants such as:
How do antispasmodics work?
The movement of food along your gut (intestines) happens because some of the muscles in the gut tense (contract) and then relax in a regular pattern throughout the length of the gut. These muscle contractions are brought about by various chemicals produced by your body which stick to special 'docking' sites (receptors) on the muscles.
However, in conditions such as irritable bowel syndrome (IBS) these muscle contractions can occur too often or be painful, causing symptoms such as pain and bloating.
Antimuscarinics work by attaching to the receptors and in this way stopping the chemicals from 'docking' there to make the muscle contract. Reducing the muscle contractions in this way often helps to relieve some of the symptoms caused by 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.
Which 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 tummy (abdominal) pain.
- To reduce the movement (motility) of the gut (intestines).
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 as 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.
The smooth muscle relaxants tend to have fewer side-effects, so they are usually tried first.
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 for?
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.
If you have IBS you may become used to having gut (intestinal) 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 back passage (rectum).
- Blood in your stools (faeces) - this may colour your stools 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 them. In particular, antispasmodics may not be suitable for people with:
- Paralytic ileus - a condition where the gut (intestinal) muscles are paralysed.
- A blocked gut (intestinal obstruction).
- Myasthenia gravis - a condition causing muscle weakness.
- Pyloric stenosis - narrowing of the outlet from the stomach.
- Prostate gland enlargement.
Pregnant or breastfeeding mothers should also seek advice before using these medicines. Avoiding these medicines if possible is usually recommended if you are pregnant or breastfeeding.
Can I buy antispasmodic medicines?
You can buy some antispasmodics from your pharmacist. Others 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. In general, the smooth muscle-relaxant types tend to have fewer side-effects. The side-effects depend on which of the antispasmodic medicines you are taking. Some of the more common side-effects are:
- Dry mouth
- Difficulty passing urine
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 a 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 www.mhra.gov.uk/yellowcard.
The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products 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.
- 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 reading and references
Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care; NICE Clinical Guideline (February 2008, updated April 2017)
British National Formulary (BNF); NICE Evidence Services (UK access only)
Irritable bowel syndrome; NICE CKS, October 2020 (UK access only)