What are cough medicines
Cough medicines are a group of medicines. These aim to either suppress a dry cough, or to help you to cough up the extra phlegm (mucus) of a chesty cough when you have an Upper Respiratory Tract Infection (URTI).

Cough medicines that aim to help suppress a dry cough are sometimes called antitussives. Cough medicines that aim to help you cough up extra mucus are sometimes called expectorants.
How do cough medicines work
Antitussives are said to work by reducing the cough reflex.
Expectorants are said to increase the amount of phlegm (mucus) made by the lungs. This would make secretions easier to remove by coughing.
Antihistamines reduce histamine release. This reduces congestion and decreases the amount of secretions made by the lungs.
Decongestants cause the blood vessels in the lungs and nose to narrow (constrict), and this reduces congestion.
What’s in a cough
Generally speaking, coughing is perfectly normal. A cough can help to keep your throat clear from phlegm and other irritants. However, sustained coughing can also be symptomatic of a number of conditions. Irritants are substances in the air that irritate your throat or nasal passages and can cause coughing. A cough is your body’s way of rejecting that irritant.
Sometimes the irritant comes in the form of an allergen, such as pollen or pet dander. This causes your body’s immune system to create chemicals called histamines that react to the allergen. If you have a cough that arises immediately in a certain environment or season, you may have an allergy.
Some important considerations
Children under 6 years old – For children under 6 years of age, only give them simple preparations such as glycerin, honey, and lemon. Do not give children who are younger than 6 years old cough medicines 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 medicine.
Taking other medicines – Always check with your pharmacist before buying any 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).
What is the usual length of treatment
As with all medicines, cough medicines should only be taken for the shortest period of time necessary, and most people only need to 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 this then you should go to see your doctor.