Most over the counter medicine can be taken up to 2 years past the expiration date of the medicine.
A lot of over the counter medicine such as aspirin and other pain medicine, cold medicine etc are still good to take for 2 years and sometimes longer past the expiration date on the medicine.
When medicine is stored under reasonable conditions the medicine will retain at least 70% to 80% of their original potency for at least 1 to 2 years past the expiration date on the medicine.
However that is mainly for over the counter medicines and not for prescription medicines such as Insulin, nitroglycerin, liquid antibiotics.
But for most other prescription medicines they remain safe to take for up to 2 years past the expiration date.
But it's best to use the medicine up before expiration date because once the expiration date arrives the medicines starts losing some of it's effectiveness.
But there's no harm in taking expired medicine as long as it's not the Insulin, nitroglycerin or liquid antibiotics.