Question 1

how can you know if have an allergic reaction to cephalexin ?

Accepted Answer

Timing, symptoms: There are different kinds of reactions one can have to antibiotics.  There are many factors in the history which help diagnose this (timing of the reaction in proximity to the antibiotic, oral/iv, past history, family history).  An allergist can perform testing to help confirm Cephalexin allergy if necessary.

Question 2

how long until i see the effects of prednisone for an allergic reaction to cephalexin , severe rash?

Accepted Answer

A few days: You should start seeing improvement hopefully within a few days. Using a topical steroid cream with the oral steroid can also help quicken recovery. If it is not improving, let your physician know.

Question 3

cephalexin side effects and safety? allergic reaction risk?

Accepted Answer

Urticaria: Cephalexin is an oral antibiotic, belongs to the class of 'cephalosporin'. People who are allergic to 'penicillin" in general, will have cross sensitivity reaction to cephalosporin as well. The drug reaction can vary from mild urticarial rash to severe anaphylaxis,  which will be life a threatening situation.  Sometimes cephalosporin can give 'drug induced fever' as well. Good luck !

Question 4

if i got an allergic reaction from cephalexin, does that mean i am also allergic to penicillin?

Accepted Answer

No: There is indeed crossreactivity, but:
-if you are allergic to cephalosporins like cephalexin, and have had penicillin with no problem in the past, most patients can continue taking penicillin without problems. 
-if you have not had penicillin since this reaction to cephalexin, you should see a physician who could to test you to penicillin, ideally an allergist.

Question 5

i started taking cephalexin. as i have  had mild allergic reaction to penicillin , should i expect  serious allergic reactions  to this medicatiion?

Accepted Answer

Mostly not: The incidence of cephalexin allergy in patients with penicillin allergy is in the single digit % and likely not much different from patient without a history of penicillin allergy.  However if you had a severe anaphylactic reaction to penicillin, I would suggest an allergy consult just to be safe .

Question 6

i was put on cephalexin for an infection 2 days ago.the lymph node in my right jaw and neck hurt and i threw up.could this be an allergic reaction?

Accepted Answer

Your tummy: Is possibly very sensitive to this type of antibiotic.  Try not to take the antibiotics on an empty stomach and see what happens.  If this persists see your doctor for a different type of antibiotic.  This most likely is not an allergic reaction just a case of sens. Stomach.

Question 7

i had a severe allergic reaction to keflex. can i trust taking other antiobios in the future without being pre-tested? how to know if allergic again?

Accepted Answer

No penicillin: I'd avoid all penicillins and cephalosporins (of which Keflex is one), the latter having about a 5% cross reactivity to penicillin, until i can get tested.  There are plenty of other antibiotic types which can be used, if needed, such as sulfa based antibiotics and quinolones. Speak to your doctor so you can be prepared in the event of an infection . Good luck!

Question 8

always fine w penicillin, but had extreme allergic reaction reaction to keflex! does that mean i am now also allergic to penicillin for sure?

Accepted Answer

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.

Question 9

how long will an allergic reaction rash from keflex last? i was on the pills for 13 days before the dr finally said it was an allergic reaction

Accepted Answer

Days to weeks: Can last days to weeks.  Itching usually goes away within a week.  But lesions from rash can last several weeks before they completely fade.

Question 10

my 2 1/2 year has an allergic reaction to keflex has hives all over body how much benedryl can i give her she is 28 lbs ?

Accepted Answer

Benadryl (diphenhydramine) dosing: Benadryl (diphenhydramine) is effective between 0.5 to 1.0 mg/kg per dose every 8-12 hrs.  Based on pt being 28 lbs then a tspn of benadryl (diphenhydramine) 12.5mg/5ml will give pt 12.5 mg which is about 1 mg/kg.

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Doctor answers about:

Symptoms of allergic reaction to cephalexin

A member asked:

How can you know if have an allergic reaction to cephalexin ?

A member asked:

How long until i see the effects of prednisone for an allergic reaction to cephalexin , severe rash?

A member asked:

Cephalexin side effects and safety? allergic reaction risk?

A member asked:

If i got an allergic reaction from cephalexin, does that mean i am also allergic to penicillin?

A member asked:

I started taking cephalexin. as i have had mild allergic reaction to penicillin , should i expect serious allergic reactions to this medicatiion?

A member asked:

I was put on cephalexin for an infection 2 days ago.the lymph node in my right jaw and neck hurt and i threw up.could this be an allergic reaction?

A member asked:

I had a severe allergic reaction to keflex. can i trust taking other antiobios in the future without being pre-tested? how to know if allergic again?

A member asked:

Always fine w penicillin, but had extreme allergic reaction reaction to keflex! does that mean i am now also allergic to penicillin for sure?

A member asked:

How long will an allergic reaction rash from keflex last? i was on the pills for 13 days before the dr finally said it was an allergic reaction

A member asked:

My 2 1/2 year has an allergic reaction to keflex has hives all over body how much benedryl can i give her she is 28 lbs ?

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