 [ Symptoms ] i have an allergy to amoxicillin can i take cephalexin 500 mg [ Disease ] some people not all who are allergic to penicillins are also allergic to cephalosporins some studies show that it is safe for penicillin allergic people to take this class of antibiotics but there is a still a long standing warning against it since i do not know anything about you or your allergic history it is always best to address this question directly with your medical provider    someone who knows your medical history