Cough medicines

What are cough medicines?

Cough medicines or cough syrups aim either to suppress a dry cough, or to help you to cough up the phlegm (mucus) of a chesty cough when you have a URTI. There is no good evidence that they do help. This is partly because many coughs get better quickly on their own anyway, so it is hard to tell if the cough medicine has helped or if the cold has simply got better.

Lots of cough medicines are available to buy from pharmacies or supermarkets. They usually contain one or more active ingredient (see the section below).

A glycerin, honey and lemon cough medicine is also available to buy. This preparation does not have an active ingredient as such. It is thought to have a soothing action.

Cough medicines can also contain other medicines such as paracetamol or ibuprofen. Some contain alcohol.

How do cough medicines work?

If cough medicines do work, they are thought to work in different ways, depending on what the active ingredient is:

• Antitussives are said to work by reducing the cough reflex. For example, dextromethorphan.

• Expectorants try to help loosen secretions, so you cough up the mucus. For example, guaifenesin or ipecacuanha.

• Antihistamines reduce histamine release. This reduces congestion and decreases the amount of phlegm made by the lungs. Examples are brompheniramine, chlorphenamine, diphenhydramine, doxylamine, promethazine or triprolidine.

• Decongestants cause the blood vessels in the lungs and nose to narrow (constrict), which reduces congestion in the nose. Examples are phenylephrine, pseudoephedrine, ephedrine, oxymetazoline or xylometazoline.

Do cough medicines really work?

There is no good evidence from research studies that cough medicines work. It is thought that they have little benefit on the cough (or cold) symptoms. However, some people feel that they work for them, and most cough medicines are considered to be safe for the vast majority of adults and for children over 6 years old.

Which cough medicine should I buy?

If you have a dry cough, a preparation containing an antitussive such as dextromethorphan is the most suitable to try. If you have a chesty cough, a preparation containing an expectorant such as guaifenesin or ipecacuanha is the most suitable to try.

Your pharmacist can advise you which one may be suitable for you. If you are buying these cough medicines from the supermarket, the box should clearly state which type of cough it aims to help and what the ingredients are.

Cough medicine for children

Children under 6 years old

Children under 6 years of age should only be given simple cough syrups such as glycerin, honey, and lemon. Cough syrup boxes will show what age of child it is appropriate for. Do not give children who are younger than 6 years old cough syrups with any of the active ingredients listed above (antitussives, expectorants, antihistamines, or decongestants). This is because the risk of a young child having a side-effect to one these preparations is greater than any possible benefit of the cough medicine.

Children aged 6 to 12

Children older than 6 years old can usually take cough medicines safely. In the UK, they are only sold for the use of children aged 6 to 12 with the advice of a pharmacist. Consider other soothing measures first as any cough medicines can have side-effects.

Taking other medicines

Always check with your pharmacist before buying any cough medicines from the chemist or supermarket to see if they are safe to take with any other medicines you may be taking.

Some cough medicines contain other medicines as well. For example, some may contain paracetamol or ibuprofen, and some contain alcohol. This is important if you are already taking paracetamol or ibuprofen to help the symptoms of your infection (for example, a high temperature). This is because you may take too much paracetamol or ibuprofen (an overdose) but not be aware of it. Taking too much paracetamol can seriously damage your liver.

Monoamine-oxidase inhibitors

If you are taking a particular type of antidepressant - a monoamine-oxidase inhibitors (MAOI) - this can react with certain ingredients in cough medicines. Taking these together can cause a very large sudden increase in blood pressure, or make you very excitable or depressed.

In particular, people taking MAOIs should avoid dextromethorphan, ephedrine, pseudoephedrine or phenylpropanolamine while they are taking an MAOI antidepressant and for two weeks after it is stopped:

• Dextromethorphan when taken with an MAOI antidepressant may make you very excitable or depressed.

• Ephedrine, pseudoephedrine and phenylpropanolamine, when taken at the same time as an MAOI antidepressant, may cause very large increases in blood pressure.

Cough medicine side-effects

Most people who take cough medicines do not have side-effects. Some cough medicines (for example, diphenhydramine) can cause drowsiness. If you are drowsy after taking a cough medicine, you should not drive and you should not operate machinery. The leaflet that comes with your cough medicine will state if the medicine can cause drowsiness.

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

What is the usual length of treatment?

As with all medicines, cough medicines should only be taken for the shortest period of time necessary, most people only use a cough medicine for a few days. In general, most coughs do not last more than 2-3 weeks. If your cough does last longer than three weeks then you should go to see your doctor.

Who cannot take cough medicines?

Most people can take a cough medicine. The exception is children under the age of 6 years. These children should only be given cough syrups with no active ingredients (see above).

Cough medicines for children aged 6 to 12 are only sold with the advice of a pharmacist. If you are taking any other medicines or you are not sure if you should take a cough medicine, check with your pharmacist.