Sneezy, this one’s for you: Unbeknownst to many people, antihistamines and decongestants—the two go-to treatments for allergy sufferers—are not the same thing. In fact, they affect the body in very different ways. Decongestants work by contracting the small blood vessels in the membranes of your nose, slowing the flow of mucus, and are designed to give you immediate relief. Antihistamines, however, work throughout the entire body to block the effects of symptom-inducing histamines in the first place (which is why they work best when taken before symptoms occur).

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