http://www.medications.com/effect/view/39039 After 8 days of taking bactrim I woke up to bad hives all over my body! The itching was soooooo bad. I was scratching myself bloody. I took benadryl and it did not help. My doc gave me prescription antihistamines and it took about 4-5 days. Mon, 09 Mar 2009 23:27:20 -0400 http://www.medications.com/effect/view/39039?item=17832 The same thing happened to me, I woke up after 6 days of taking Bactrim with hives all over my body. The nurse at my doctors office suggested this medication, (I can't wait to see her again). I am covered in hives and so miserable, nothing seems to stop http://www.medications.com/effect/view/39039?item=17832