Drug allergy can be very complicated. Oftentimes, the diagnosis is made through a careful history and physical. Many times, rashes attributed to drug allergy in a patient's history are red herrings. If someone has a history that is inconsistent with a classic drug allergy that could cause anaphylaxis, we will often perform a drug challenge first, skipping the unnecessary time, cost and discomfort of skin testing. If the reaction is consistent with classic drug allergy, we can perform skin testing. Skin testing to medications can also be fraught with difficulty. The best studied medication for skin testing is penicillin. Local anesthetic testing is also fairly well-studied. If the medication is absolutely necessary and the patient is allergic we can desensitize them to the medication in question in many cases. We cannot desensitize patients if the reaction is Stevens-Johnson syndrome or erythema multiforme. We also offer aspirin desensitization for patients who have aspirin sensitivity with either nasal polyps or asthma.