Many experts question the use of cough medicines because clinical trials have not found that cough medicines are any better than a placebo or dummy treatment.
The NHS says there are no shortcuts with coughs caused by viral infections. It just takes time for your body to fight off the infection. In the meantime, you may still want to relieve the symptoms of the cough.
Doctors won't prescribe antibiotics for coughs because they don't work against viruses.
If your cough has lasted longer than 3 weeks, seek medical advice.
Cough medicine: Lack of evidence
The NHS says there's not much scientific evidence that cough medicines work, although it says some ingredients may help with other symptoms of a cold.
Make sure you read the label to check whether the cough medicine contains paracetamol, so you don't end up taking too much, for example by having paracetamol tablets as well as the cough mixture.
Usually, cough medicines shouldn't be taken for more than two weeks without medical advice.
People with diabetes should check the sugar content of cough medicines.
Cough suppressant or expectorant?
For a dry cough, suppressants are medicines to help block the body's reflex to cough. Ingredients include pholcodine, dextromethorphan and antihistamine.
Some cough suppressants have side effects, such as drowsiness, dry mouth or constipation.
For a chesty cough with phlegm, expectorants can help you 'cough it up' and ease the cough.
An expectorant is a medicine that thins mucus so you can cough it up more easily. The ingredients you will typically see in cough expectorant are guaiphenesin, ammonium chloride, squill, sodium citrate and ipecacuanha.
These medicines are unlikely to cause side effects for most people.
Children and cough medicine
Never give over the counter cough and cold medicines to children aged under six years old. The UK medicines regulator MHRA says there is a risk of these medicines causing side effects including allergic reactions, disturbed sleep or hallucinations.
If your child has a cough, always check with your doctor or pharmacist before giving any medication if you are unsure, and always read the label.
A home-made warm honey and lemon drink may sooth children aged over one year old. Before 12 months old, babies are at risk of botulism from honey so shouldn’t be given honey.
What’s a combination cold and cough medicine?
Many over-the-counter cold and cough syrups and cough medicines contain a cough suppressant (dextromethorphan) plus an expectorant (guaifenesin) as well as other cold medicines and pain relievers. The combination cold and cough medicine may contain an antihistamine, a decongestant, and a pain reliever in addition to the cough suppressant and/or expectorant. The combination of medicines may give optimal relief if you have multiple cold symptoms, such as sore throat, cough, and congestion. The downside of the combination cold medicines, depending on your symptoms, is that you may be taking medication that you don’t need.