Phenylephrine is a medication that’s been used to relieve nasal congestion caused by colds, allergies, and hay fever, per the U.S. National Library of Medicine.
Phenylephrine is widely used in a variety of over-the-counter flu and cold medicines, including popular products such as Benadryl, Advil, and Tylenol. It is also an ingredient in nasal sprays to treat ...