Question: what is difference between antihistamine and decongestant?
Answer: If you have nasal or sinus congestion, then a decongestant can be helpful. If you have drainage -- either a runny nose or postnasal drip or itchy, watery eyes -- then an antihistamine may be helpful. Over-the-counter antihistamines often make people drowsy; decongestants can make people hyper or keep them awake.