Sinusitis is the most common culprit, but asthma, chronic bronchitis and the common cold also are factors. If a cough persists more than a few days, however, a physician should be consulted. By learning more about how these drugs act to inhibit cough, we hope to design newer, more effective drugs relatively free of side effects. Many consumers have misconceptions about cough preparations. Central drugs, such as codeine, often are more effective but are associated with side effects such as drowsiness and constipation.
Codeine also can be addictive.
Not all antihistamines inhibit coughing, though they may help alleviate other cold symptoms. If the drug's name ends in 'amine', it probably contains an antihistamine. Have realistic expectations of expectorants. An expectorant commonly found in cough suppressants is guaiphenesin. If you want a cough suppressant that doesn't make you sleepy, look for preparations containing only dextromethorphan.