Doxycycline has a 2 year shelf life. After that, it can turn toxic. Other tetracyclines may be even more toxic after expiration. Expired tetracyclines damage the kidneys.
FWIW, I was once told by a physician that even freeze dried penicillin had a 3-year shelf life.
The pharmacists/clinicians here can comment with more authority.
“Doxycycline has a 2 year shelf life. After that, it can turn toxic. “
Yea, I saw that...definitely keep clear. But that seems to be the only ones that really get harmful (rather than lose potency)...so having 50% Amox definitely beats 0%, after ‘it’ happens.
In some cases its the binder which turns toxic and not the medicine itself. Many medicines become less effective with age but don’t turn toxic.
The link Kartographer provider earlier is a good reference and provided by an MD - http://www.survivalblog.com/2010/07/a_doctors_thoughts_on_antibiot.html