Studies and case reports are lacking on this topic. In 1963, a report was published that tied degraded tetracycline use with a form of renal tubular (kidney) damage known as “Fanconi Syndrome”; however, that formulation of tetracycline in no longer marketed in the U.S.1, and many medical experts question the results of this case report.
Solid dosage forms, such as tablets and capsules, appear to be most stable past their expiration date. Drugs that exist in solution or as a reconstituted suspension, and that require refrigeration (such as amoxicillin suspension), may not have the required potency if used when outdated. Loss of potency can be a major health concern, especially when treating an infection with an antibiotic. Additionally, antibiotic resistance may occur with sub-potent medications. Drugs that exist in solution, especially injectable drugs, should be discarded if the product forms a precipitant or looks cloudy or discolored.1
Expired medications that contain preservatives, such as ophthalmic (eye) drops, may be unsafe past their expiration date.1 Outdated preservatives may allow bacterial growth in the solution.
