2 doctors weighed in:

I had an allergic reaction to bactrim (sulfamethoxazole and trimethoprim) on 1/11/14 (swollen lips and rashes on abdomen & back arm). I was given doxycycline hyclate. Rash became bumps?

2 doctors weighed in
Dr. John Chiu
Internal Medicine - Allergy & Immunology

In brief: Bactrim (sulfamethoxazole and trimethoprim)

If you meant that the rash was progressing without interruption despite switching to doxycycline, i would venture that the rash is just from the progression of the sulfa rash since the process will likely last for a week or two.
Beware of sunlight exposure from doxycyline which may give a nasty sunburn for some people.

In brief: Bactrim (sulfamethoxazole and trimethoprim)

If you meant that the rash was progressing without interruption despite switching to doxycycline, i would venture that the rash is just from the progression of the sulfa rash since the process will likely last for a week or two.
Beware of sunlight exposure from doxycyline which may give a nasty sunburn for some people.
Dr. John Chiu
Dr. John Chiu
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Dr. Keith Ramsey
Pediatrics - Adolescent Medicine

In brief: Take Benadryl (diphenhydramine)

For 1-2 weeks, at least twice a day.
Sometimes an allergy to Bactrim (sulfamethoxazole and trimethoprim) can become severe. If you develop blisters, red eyes, red lips, then you need to be seen and might need steroids. The Doxycycline is probably not responsible for the worsening. Allergic rashes can become worse even after you stopped the bactrim (sulfamethoxazole and trimethoprim). Good luck.

In brief: Take Benadryl (diphenhydramine)

For 1-2 weeks, at least twice a day.
Sometimes an allergy to Bactrim (sulfamethoxazole and trimethoprim) can become severe. If you develop blisters, red eyes, red lips, then you need to be seen and might need steroids. The Doxycycline is probably not responsible for the worsening. Allergic rashes can become worse even after you stopped the bactrim (sulfamethoxazole and trimethoprim). Good luck.
Dr. Keith Ramsey
Dr. Keith Ramsey
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