Which OTC cough remedy uses a cough suppressant intended for nonproductive cough and should be avoided when the cough is productive?

• A. Dextromethorphan
• B. Diphenhydramine
• C. Guaifenesin
• D. Pseudoephedrine

Answer: (A)

Key idea: in cough remedies, antitussives suppress the cough reflex, which is helpful for a dry, nonproductive cough but not when mucus needs to be cleared.

Dextromethorphan is a common OTC cough suppressant that acts on the cough center in the brain to reduce coughing. This makes it appropriate for a nonproductive, dry cough where suppressing the urge to cough provides relief. However, if the cough is productive, you want to clear mucus from the airways, not suppress the cough reflex. Using a suppressant in a productive cough can trap secretions, potentially prolonging illness or increasing the risk of complications.

The other options aren’t primarily the antitussive choice for a dry cough. Guaifenesin is an expectorant that helps loosen and thin mucus to make it easier to cough up. Pseudoephedrine is a decongestant that relieves nasal congestion. Diphenhydramine is an antihistamine with some antitussive effects, but it’s not the typical agent identified for treating a nonproductive cough in OTC therapy.

So, the remedy that uses a cough suppressant intended for nonproductive cough—and should be avoided when the cough is productive—is the one containing dextromethorphan.