I am a male who weighs 165lbs. I was prescribed Cephalexin at a dosage of 750 mg twice daily for a week for sinusitis. Can this medication cause a Biliary Obstruction? Moreover, I know my genetic brother has a allergy to Penicillin. Does the fact my brother has an allerigic reaction mean I too am allerigic to the medication. Futhermore, is there a cross reactivity, rather would a allergy to Penicillian denote an allergy to Cephalexin? If so, can an allergy to Cephalexin cause Kidney failure? Thank you for your time and aide in answering these questions.