Antitussive

adj. prevents or reduces coughing

A cough medicine is a medicinal drug used to treat coughing and related conditions. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants that loosen mucus from the respiratory tract. These medicines are widely available in the form of cough syrup, also known as linctus.
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Antitussive /an·ti·tus·sive/ effective against cough, or an agent with this quality. an·ti·tus·sive adj. [more]Antitussive - Community and Resources

Noun
1. any medicine used to suppress or relieve coughing
(hypernym) medicine, medication, medicament, medicinal drug
(hyponym) codeine

adj. antitussive, prevents or reduces coughing