What Are The Side Effects Of Acetaminophen?

When I am fighting an infectious disease like a flu, even when I do not have a temperature, and I take ibuprofen (my favorite OTC pain medicine), I break into a cold sweat 20 or 30 minutes after I take it. Acetaminophen does not cause this. Any clue why this happens to me? Are there others who have experienced this immune reaction sweat blast?