>>11774846depends on the substance and conditions you keep them in
as long as you keep them out of UV light and excessive temperatures most will be fine long after the expiration date with only a small loss of effectiveness if anything, but there are a few exceptions like tetracycline antibiotics that can break down into toxic products and possibly fuck you up if they sit around too long
for liquids like nitroglycerine or insulin or anything that needs to be kept cold expiration is definitely a concern, but most pills will be totally fine and the expiration date is just for manufacturer ass covering in case anything does happen
