Allergic drug reactions occur when the immune system mistakenly identifies a medication as harmful. This can lead to various symptoms, ranging from mild rashes and itching to severe reactions like anaphylaxis, which can be life-threatening. Common medications that may cause allergic reactions include antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and certain vaccines. Diagnosis of an allergic drug reaction typically involves a review of the patient's medical history and symptoms. Treatment may include stopping the offending medication and using antihistamines or corticosteroids to alleviate symptoms. In severe cases, emergency medical attention may be necessary to manage the reaction effectively.