Why does Keflex have a strong odor?

Answer 1

I found this comment here: http://yarchive.net/med/penicillin.html

"df" <defranc...@Yahoo.com> wrote:

> I notice that my bottle of Keflex 500mg capsules smells like rotten

> eggs. The bottle was only filled last week. Is this normal?

>>Apparently. I remember smelling that when I was taking it. I think

sulfur is part of whatever Keflex is made of. <<

COMMENT:

Indeed. All the antibiotics in the penicillin and cephalosporin class

(of which Keflex/cephalexin is one) have the beta-lactam ring nucleus,

which contains a sulfur atom. Breakdown products and impurities, even

in new and well manufactured pills, lead to that sulfury smell. It's

especially apparent in tablets (ie Pen VK) and capsules (like your

Keflex), and not so bad in the film coated more-expensive members of

the class like Ceftin (though you can still detect it in cut pills). So

you'll smell a trace of sulfur in the drug itself, and if not, you'll

certainly smell it after it's passed through your gut.