Why do common household items (shampoo, toothpaste, medicine, etc.) have expiration dates and what happens once the expiration date passes?

Question

Why do common household items (shampoo, toothpaste, medicine, etc.) have expiration dates and what happens once the expiration date passes?

In: Other

Answer 1

I’d say nothing, as it takes me a well over a year to use a bottle of shampoo and I don’t notice any difference near the end of the bottle.