Urticaria

Why does a person who has had 2 children start getting urticaria after taking an antibiotic course of 10 days the third time she takes it? Then next time the doctor prescribes her on another type of antibiotic and then same thing happens, she is okay the first time she has to take it and usually the second but around the second or third time over a course of 3 to 5 years, she gets the urticaria again after taking the same antibiotic that she used for 3 or more years. Then the same pattern happens with other antibiotics that she has to take for a UTI etc., so that now she can only take one antibiotic that has not yet caused her to get urticaria. But the doctors are running out of antibiotics to give her for bronchitis etc. etc. Why is this? What can be done to prevent it? This same person has been a few times over the years for allergy skin tests and they tell her that she is only mildly allergic to this or that. The allergist told her that she is in the 20% that do not respond to allergy skin tests meaning that he does not know what she is allergic too but she is and thus she cannot get allergy shots because he does not know what she is allergic too? What is the answer? Have you ever heard of this happening to others? Is it because of drastic hormon changes after having kids? But in her case it happened a few years after having the baby....this is so strange.

[Dr_Subir]

After pregnancy, human physiology can change a bit. Also, you can become allergic to a drug even if you were not allergic to it before. But, she won't become allergic to all the antibiotics. This happens, don't worry.

[deanieken]

Thanks for your response. The antibiotic families that she is allergic to are penicillin---ampicillin got her 26 years back after she had peritinitis; the other specific antibiotics are zithromax; macrobid and avelox...these are the ones she used that gave her urtica or hives and she had to get on prednisone etc. When she went to get bactrum as prescribed by a gynecologist, the pharmacist told her she was allergic to sulfa family drugs so not to take it. When she takes clindomycin or other antibiotics, even with taking some acidopholis, for tooth issues, she gets diarrhea after taking about the 3rd pill. This is not an allergy...we know...it is just a side effect of that drug. As we said the only antibiotic so far that seems to be okay for her to use is doxycycline...but she has been on that for 3 years and hopefully she won't also develop an allergy to that one too. A urologist told her that she should worry about being allergic to all these meds and you are saying not to worry. Who is correct?