The active ingredients in cough mixtures may be categorised into various groups. Each group helps to relieve particular symptoms.
- Bronchodilators help to ‘open the chest’ and decrease symptoms such as wheezing and shortness of breath. Expectorants are given to stimulate coughing, helping to clear mucus from the airways.
- Mucolytics change the consistency of mucus, making it less sticky and easier to cough up.
- Cough suppressants reduce the cough reflex and decrease the incidence of coughing.
- Antihistamines may be used in cough preparations to suppress the cough reflex and dry mucus secretions causing postnasal drip.
- Decongestants may be included in cough preparations for airway relaxing and decongestant effects.
Choice of cough preparation
When a cough preparation is chosen for a particular patient, all aspects of the cough must be considered. If an underlying disease causes the cough, this should be addressed before a cough preparation is used. Once the cause of the cough is identified and treated, the objective is to shorten the duration of the cough and decrease the possibility of complications.
Choice of preparation is based on the symptoms described. Most patients will experience more than one symptom and thus combination products are useful.
- Bronchodilators are useful when the patient’s chest feels tight or if they are short of breath.
- Expectorants and mucolyticsare given for productive coughs.
- Suppressants are used for dry, non-productive, tickly coughs. They should not be used if phlegm is present as this may increase risks of further infection.
- Antihistamines are useful if the cough is caused by postnasal drip or a cold.
- Decongestants may be used when the cough is due to nasal congestion.
Some combinations such as an expectorant with a suppressant appear to be contradictory, but may be useful in certain situations.
When a patient presents with a cough a thorough history should be taken to determine whether the problem can be dealt with using an over-the-counter remedy or whether further examination is necessary. The selection of cough preparation can be made based on the symptoms and description of the cough. When in doubt, consult the pharmacist. A doctor must evaluate any cough that has been present for more than two weeks or that produces discoloured mucus.