If I'm allergic to keflex antibiotics am I allergic to penicillin?I was put on Keflex antibiotics and found out that I was severly allergic to it,...

Keflex (or Cephalexin) is a 1st Generation Cephalosporin.
Just as Wannam mentioned, they are Beta-Lactam drugs that inhibit cell wall synthesis,
but they are less susceptible to penicillinases.

There is a
5-30% chance that you can have a cross-sensitivity.