This issue of the Medical Clinics of North America brings the internist up to date on the latest approaches to drug hypersensitivity. Acute symptoms and reactions such as urticaria, angioedema, anaphylaxis, anaphylactic shock are covered. Delayed symptoms such as MPE, SDRIFE, delayed urticaria, vasculitis, Stevens-Johnson Syndrome, toxic epidermal necrolysis, AGEP, and DRESS/D(i)HS are also covered. Complex clinical pictures are explored, including the side effects to biologics, anticoagulation (including HIT), and cytostatic drugs (such asoxaliplatin, cisplatin, paclitaxel, and others). Other topics include perioperative anaphylaxis, betalactam hypersensitivity, and NSAID intolerance.