The most allergenic drugs are generally penicillin, some antibiotics, painkillers like aspirin and other non-steroidal anti-inflammatory drugs (called NSAIDs). However, you can also be allergic to other drugs, including insulin, anticonvulsants, anesthetic, blood products or others.

Interestingly enough, aspirin and NSAIDs can trigger an allergic-type reaction without IgE. Somehow, this class of drug can engage the allergic mast cells without the IgE antibody. In fact, a number of drug reactions can trigger allergy without IgE, including IV X-ray dyes, pacilitaxel, vancomycin, opiates and ACE inhibitors.