There is not enough evidence to show that over the counter cough medicines help to treat the coughing symptom but they can be effective in some people. The NHS Direct and Netdoctor websites have more details on different types of over the counter treatment. In summary there are three main types of cough medicine:
Simple cough mixtures e.g. glycerine, lemon and honey – for either type of cough, they soothe the throat
Expectorants e.g. ipecacuanha – for chesty coughs that are producing phlegm, these act on the brain to stimulate the coughing reflex to remove the phlegm
Suppressants e.g. pholcodine, antihistamines – for dry, tickly coughs that aren’t producing phlegm, these act on the brain to reduce coughing
If your symptoms are worsening, e.g. if you have trouble breathing, have a high fever, become confused or cough up blood you should see a doctor. Your cough however may take up to 4 weeks to fully settle and as long as you are not unwell in yourself you do not need to see the doctor.