Some show I watched about this years ago also said the worst place to keep your drugs was in the bathroom medicine cabinet (due to the high warm humidity). Also, my shampoo has an expiration date. Why would shampoo have an expiration date? I think they’ve gone overboard with them. It is a good way to get people to throw out the old stuff and head to the store to buy replacements.
IIRC, at least some shampoos are made using egg products, which would explain the expiration date.