Why do pharmaceutical drugs have a sell-by/use-by date? Are they less effective after their approximate shelf-life?

Question

This may not actually be a chemistry question.

In: Chemistry

Answer 1

Some drugs might get a bit less effective after their use-by date, but in the vast majority of cases the decrease in potency is insignificant. A few drugs might also develop harmful side effects and bacterial growth on them if you keep them for a long time past their use-by date.