These medicines are also known as antimotility drugs. They work by slowing down the action of your bowels. They include:
You can buy loperamide yourself from a pharmacist. You can also buy co-phenotrope over the counter, but it should only be used for people over 16.
Some good-quality studies have found that loperamide helps diarrhoea clear up more quickly. In some studies, people who took it were better after a day.   Loperamide can help people who get diarrhoea when travelling as well as people who get it at home. Two studies found it helped to reduce the need to go to the toilet so often and to clear up diarrhoea more quickly.  
A review of six studies found that more people with traveller's diarrhoea who took loperamide along with antibiotics recovered more quickly - most commonly within a day or two - than people who took antibiotics alone.  But the studies were designed quite differently and we don't know if they compared like with like. We also do not know if the benefits would apply to people who are not travelling.
Taking co-phenotrope for diarrhoea can also help you go to the toilet less often.  But in the studies we looked at, people's diarrhoea didn't clear up any faster.
You may get constipated if you take loperamide. In one of the studies, a quarter of people taking loperamide got constipation, compared with 7 in 100 people taking a dummy treatment (a placebo) for comparison. 
Some people get other side effects from loperamide. These include dizziness, drowsiness, or a dry mouth.  
You shouldn't take loperamide if you have a fever, or if there's blood or mucus in your stools.  If you have these symptoms, see a doctor.
You should stop taking loperamide and see your doctor straight away if you have any of these side effects, which could be serious:  
The research on co-phenotrope didn't mention side effects. But we do know that if you take it regularly you can become dependent on it.  Being dependent means you get unpleasant withdrawal symptoms when you stop taking it. It can also react with other drugs, so it's important to check with your doctor or pharmacist before you take it.
Stop taking co-phenotrope straight away and see your doctor if you have any of these symptoms: