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A 42-year-old member asked:

If i'm allergic to penicillin is it safe to take keflex pulvales?

1 doctor answer1 doctor weighed in
Dr. Paul Carter
A Verified Doctoranswered
A US doctor answeredLearn more
No: If you are truly allergic to penicillin, you should avoid all penicillin derivatives and the first generation cephalosporins. Keflex is a first gen. Cephalosporin and may cross react with penicillin. See a board certified allergist to help you determine if penicillin is a true allergy for you.

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Similar questions

A 21-year-old member asked:

I'm allergic to penicillin, can I take keflex?

3 doctor answers12 doctors weighed in
Dr. Alex Martinez
Specializes in Allergy
Maybe: Penicillins (like amoxil) & cephalosporins (like keflex) are both beta-lactam antibiotics named because of their ringed chemical structure. Allergy to penicillins is sometimes directed against this ring, and an allergic reaction may also occur if a similar antibiotic is taken. It is estimated that about 10% of penicillin-allergic patients are also allergic to cephalosporins like keflex.
A 36-year-old member asked:

Is it a bad idea for someone allergic to penicillin safely take keflex, a cephalosporin?

1 doctor answer2 doctors weighed in
Dr. Jeffrey Rumbyrt
Allergy and Immunology 32 years experience
Yes: Cephalexin (keflex) is a first generation cephalosporin and a very close cousin to penicillin. Though it is not 100% true that all penicillin allergic individuals are also allergic to cephalexin, there is a high likelihood of that happening.

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Last updated Oct 3, 2016

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