 [ Symptoms ] is cephalexin part of penicillin family andor is it derived from mold  skin tests show i am severely allergic to mold and when i take antibiotics from the penicillin family i have severe reactions my father is allergic to penicillin and if he takes it he will die i also cannot take erythromycin due to severe allergic reactions and my mother is allergic to it if she takes it she will die i know i can take ciprofloxacin and doxycycline but i would like to be able to take something when i get strep throat can i take keflex is it derived from mold [ Disease ] many people not all who are allergic to penicillin may also be allergic to cephalosporins like keflex so it would be wise to be skin tested by an allergist with a dilute amount to see if you have an allergic reaction keflex is not made from any mold it is synthetic