Which ingredient in many OTC decongestants is kept behind the counter due to abuse potential?

• A. Pseudoephedrine
• B. Ephedrine
• C. Phenylephrine
• D. Diphenhydramine

Answer: (A)

Pseudoephedrine is kept behind the counter because it can be used to manufacture methamphetamine, giving it high abuse and diversion potential. As a decongestant, it works by stimulating adrenergic receptors to shrink nasal blood vessels, but because of its role in illicit drug production, regulations require ID checks, purchase logs, and limits on how much can be bought. This behind-the-counter policy helps curb misuse while still allowing legitimate access for cold symptoms. Phenylephrine is another decongestant but carries a much lower abuse risk and is generally available OTC. Diphenhydramine is an antihistamine, not a primary decongestant. Ephedrine also has abuse potential and is regulated in many places, but pseudoephedrine is the classic ingredient specifically kept behind the counter for this reason.