Drug Rashes Drug rashes usually are caused by an allergic reaction to a drug. Typical symptoms include redness, bumps, blisters, hives, itching, and sometimes peeling, or pain. Every drug a person takes may have to be stopped to figure out which one is causing the rash.
Lichen planus is a skin rash triggered by the immune system. It’s not known why the immune response occurs. There may be several contributing factors, and each case is different. Potential causes include: viral infections; allergens; stress; genetics; Sometimes lichen planus occurs along with autoimmune disorders.