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I am allergic to penicillin can I take cephalexin

A 45-year-old female asked:
Dr. David Edelman
39 years experience General Surgery
Probably should not: Cephalexin is related to penicillin and there is a chance of an allergic reaction. Many people who are allergic to penicillin can take Cephalexin saf ... Read More
Dr. Ronald Krauser
52 years experience Rheumatology
Yes: Unless you had an anaphylactic reaction to penicillin (major breathing problems) there is little risk to trying cephalexin.

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A 39-year-old member asked:
Dr. Doanh Nguyen, md, faaaai
14 years experience Allergy and Immunology
Yes: Cross reactivity between the two classes are low so Cephalexin is not contraindicated in penicillin allergy patients. You should have your prescribing ... Read More
A 22-year-old female asked:
Dr. Martin Raff
56 years experience Infectious Disease
Penicillin allergy: You have what is known as an immediate hypersensitivity reaction to penicillin derivatives and should never be given one, since this is life-threateni ... Read More
1
1 thank
A 39-year-old member asked:
Dr. Brant Ward
13 years experience Allergy and Immunology
Likely, not certain: The majority of people who are told they are allergic to penicillin are not actually so (they get rashes for other reasons, e.g.). Of those that are a ... Read More
1
1 thank
A 21-year-old member asked:
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 ... Read More
2
2 thanks
A 42-year-old member asked:
Dr. Paul Carter
A Verified Doctor answered
A US doctor answered Learn 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. ... Read More
1
1 thank
A 36-year-old member asked:
Dr. Jeffrey Rumbyrt
32 years experience Allergy and Immunology
Yes: Cephalexin (keflex) is a first generation cephalosporin and a very close cousin to penicillin. Though it is not 100% true that all penicillin allergi ... Read More
6
6 thanks
A 29-year-old female asked:
Dr. Eric Stansby
26 years experience Emergency Medicine
Don't panic: Scarlet fever is an acute febrile illness, primarily affecting children, caused by group a beta-hemolytic streptococci. Clinical manifestations inclu ... Read More
4
4 thanks
A 43-year-old female asked:
Dr. Larry Lutwick
49 years experience Infectious Disease
Before it is given,: Some people who are penicillin allergic can have cross allergies to cephalosporins like keflex.
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1 thank
A 41-year-old member asked:
Dr. Robert Ramirez
18 years experience Allergy and Immunology
No: There is indeed crossreactivity, but: -if you are allergic to cephalosporins like cephalexin, and have had penicillin with no problem in the past, mos ... Read More
1
1 thank

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