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Doctor insights on: If Allergic To Penicillin Can I Take Keflex

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Dr. Alex Martinez
Board Certified, Allergy
164K people helped
1

1
I'm allergic to penicillin, can I take keflex?

Dr. Alex Martinez
Board Certified, Allergy
164K people helped
I'm allergic to penicillin, can I take keflex?

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. ...Read more

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Dr. Jane van Dis
Board Certified
13 years in practice
44M people helped
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Dr. Jane van Dis
Board Certified
13 years in practice
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Dr. Brant Ward
Board Certified, Allergy and Immunology
8 years in practice
298K people helped
2

2
Allergic to penicillin can I take keflex?

Dr. Brant Ward
Board Certified, Allergy and Immunology
8 years in practice
298K people helped

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 allergic, about 70% or more will lose the allergy after about 10 years. If you are still allergic, there is about a 10% chance of cross-reaction to 1st-gen cephalosporins like keflex. An allergist can perform testing to judge your risk for a reaction. ...Read more

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Dr. Jane van Dis
Board Certified
13 years in practice
44M people helped
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Dr. Jane van Dis
Board Certified
13 years in practice
44M people helped
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Dr. Robert Varady
Board Certified, Family Medicine
460K people helped
3

3
What to do if I have strept throat, and I'm allergic to penicillin, can take amoxicillin or keflex instead?

Dr. Robert Varady
Board Certified, Family Medicine
460K people helped
What to do if I have strept throat, and I'm allergic to penicillin, can take amoxicillin or keflex instead?

No to Amoxicillin: You shouldn't take Amoxicillin and there is a 1 in 10 chance that you'll have a reaction to Keflex. If your allergic reaction to penicillin wasn't severe, (anaphylaxis or other), then it would be reasonable to try Keflex ...Read more

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Dr. Michael Zacharisen
Board Certified, Allergy and Immunology
28 years in practice
4M people helped
4

4
What to do if I have strept throat, and im allergic to penicillin, can take amoxicillin or keflex instead?

Dr. Michael Zacharisen
Board Certified, Allergy and Immunology
28 years in practice
4M people helped
What to do if I have strept throat, and im allergic to penicillin, can take amoxicillin or keflex instead?

No : Amoxicillin is within penicillin class and the risk of having a reaction is significant so it should be avoided. There is controversy about the risk of cross reaction between class of antibiotics penicillin and cephalosporin (keflex). It appears the risk is low (but not 0). If penicillin allergy was years ago, skin testing for penicillin can help know if it is still there. Allergist can help. ...Read more

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Dr. Jane van Dis
Board Certified
13 years in practice
44M people helped
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Dr. Paul Carter
Board Certified, Allergy and Immunology
25 years in practice
2M people helped
5

5
If i'm allergic to penicillin is it safe to take keflex pulvales?

Dr. Paul Carter
Board Certified, Allergy and Immunology
25 years in practice
2M people helped

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. ...Read more

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Dr. Jeffrey Rumbyrt
Board Certified, Allergy and Immunology
27 years in practice
319K people helped
6

6
Is it a bad idea for someone allergic to penicillin safely take keflex, a cephalosporin?

Dr. Jeffrey Rumbyrt
Board Certified, Allergy and Immunology
27 years in practice
319K people helped

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. ...Read more

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Dr. Eric Stansby
Board Certified, Emergency Medicine
21 years in practice
81K people helped
7

7
I m allergic to penicillin keflex azithromiacin my daughter has scarlet fever and i m worried about what i can take if i get it ?

Dr. Eric Stansby
Board Certified, Emergency Medicine
21 years in practice
81K people helped
I m allergic to penicillin keflex azithromiacin my daughter has scarlet fever and i m worried about what i can take if i get it ?

Don't panic: Scarlet fever is an acute febrile illness, primarily affecting children, caused by group a beta-hemolytic streptococci. Clinical manifestations include fever, sore throat, and fine sand-paper like rash caused by a toxin produced by the strep. Although penicillins are antibiotics of choice, there are other antibiotics that are effective. Your doctor will know. A throat culture is helpful. ...Read more

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Dr. Michael Fisher
Board Certified, Dermatology
27 years in practice
31M people helped
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8
I am allergic to keflex & penicillin. Is neosporin still ok to use on my skin?

Dr. Michael Fisher
Board Certified, Dermatology
27 years in practice
31M people helped

Neosporin: People have a tendency to assume that neosporin does not cause side effects because it is a widely available and frequently used nonprescription product. However, this is simply not the case. In fact, many healthcare providers now recommend that people avoid products with neomycin (including neosporin), as neomycin is more likely than most other antibiotics to cause allergic reactions. ...Read more

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Dr. Joram Seggev
Board Certified, Allergy and Immunology
1M people helped
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9
Always fine w penicillin, but had extreme allergic reaction reaction to keflex! does that mean I am now also allergic to penicillin for sure?

Dr. Joram Seggev
Board Certified, Allergy and Immunology
1M people helped
Always fine w penicillin, but had extreme allergic reaction reaction to keflex! does that mean I am now also allergic to penicillin for sure?

Not necessarily: While penicillin and Cephalexin (keflex) share some features, allergy to one does not necessarily to one mean that you are allergic to the other. See a board-certified allergist/immunologist to sort things out. ...Read more

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Dr. Yelena Kipervas
Board Certified, Family Medicine
18 years in practice
241K people helped
10

10
Was recently dx'd with lupus & am allergic to Keflex. Heard that lupus patients tend to have strong reactions to penicillin, should I avoid penicilin?

Dr. Yelena Kipervas
Board Certified, Family Medicine
18 years in practice
241K people helped

Avoid penicillin: I am not aware of the connection between allergy to PCN and lupus, You need to avoid PCN if you are allergic to keflex. ...Read more

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Dr. Jane van Dis
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