bactrim rash

i had bactrim rash and raised pimples on back and chest.after 10 days of regnisone rash 90%gone but arm rash is lighter but still there and pmples on back smooth but stll there.how long for rash and pimples to completely disappear it has been 3 weeks.can bactrim rash come  back even if uoudont take bactrim

[Bhupinder Kaur, MD]

Hello,
From your post I understand that you had an allergic reaction to Bactrim( sulfa drug). Common sulfa antibiotics include Septra, Bactrim and Pediazole.You need to avoid these drugs and take some Benadryl or Claritin. Also apply calamine lotion or steroid cream on the rash after consulting a dermatologist,

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.