I recently took bactrim to get rid of PCP; it worked fine. Then about 10 days afterward, I started bactrim prophylaxis. This was yesterday - I took only one pill and came down with unbeleivable flu-like symptoms: extreme fatique, dizziness, could barely even sit up. Had to stay home from work today. Is this normal? Can I "build up" (desensitize) to avoid this? I want to keep taking bactrim if possible as I understand it's the best prophylaxis. I guess I had these side effects before, but just thought it was from being ill from the PCP itself. Please Help!

Your symptoms do not sound like the usual ones for a reaction to Bactrim. You may just have been unlucky enough to have picked up another germ after you recovered fromm PCP. You can, with your doctor's knowledge, start taking Bactrim again and see what happens. If the same symptoms come back, then you may have had an unusual reaction. Some docotrs believe in "desensitization" for Bactrim and others don't; there is no final word on this. But if you can't take Bactrim, you can try dapsone, another reasonable way to prevent PCP.