A rash is a not uncommon side effect for tapazole. I took an anti-histimine with it, and that kept the rash under control.
Do you have a sore throat? A rare but serious side effect of Tapazole is something called agranulocytosis. I don’t know what it is, or what other symptoms go along with it, but my endo told me that if I ever had a bad sore throat, I should stop the tapazole and get a blood test immediately.