Is expired cephalexin still effective or dangerous to take?

Antibiotics are a particularly bad kind of medication to play with. Due to many deterioration factors the dosage and efficacy can no longer be guaranteed.

Taking a dose insufficient to kill the infection can result in the bacteria developing a resistance to them, and drug resistant bacteria are really not a good thing. They make for good Horror flick plots, though.

ADDITIONAL INFORMATION TO CONSIDER Pay close heed to the information given above. If you take a 250mg capsule of an antibiotic it may have degraded in effectiveness after a few months. With that in mind however, you can safely take a 'some' antibiotics for certain issues. For instance I have had great success with slightly higher doses of older antibiotics. Say taking 500 mg Amoxicillin 3x per day for ten days for a specific kind of an ear ache. Studies show that expired drugs may lose some of their potency over time, from as little as 5% or less to 50% or more (though usually much less than the latter). Even 10 years after the "expiration date," most drugs have a good deal of their original potency. If your life does not depend on an expired drug - such as that for headache, hay fever, or menstrual cramps - take it and see what happens. One of the largest studies ever conducted that supports the above points about "expired drug" labeling was done by the U.S. military 15 years ago, according to a feature story in the Wall Street Journal (March 29, 2000), reported by Laurie P. Cohen. Another thing to keep in mind is that generic analogs do not keep as well as the name-brand medications. This is one of those corners that gets cut to make them cheaper. If you take them right away there is no difference at all, but over time a generic will lose effectiveness faster.