Do vitamins expire?

According to WebMD and Mayo Clinic, vitamins do expire; they become less effective over time and gradually lose all their potency. If a package of vitamins is past its expiration date, consumers are better off throwing it out and getting a replacement.

Mayo Clinic and WebMD recommend storing vitamins in cool and dry areas so that they can retain their effectiveness for as long as possible. Bathrooms tend to get humid and are poor location choices for vitamin storage. Mayo Clinic cautions against buying vitamin containers that lack expiration dates, and WebMD adds that vitamins should be kept in places that are inaccessible to children.