A drug allergy occurs when the immune system mistakenly identifies a medication as a harmful substance. This reaction can lead to symptoms such as rashes, itching, swelling, or difficulty breathing. Common medications that may cause allergies include penicillin, aspirin, and certain antibiotics. When someone has a drug allergy, it is crucial to inform healthcare providers to avoid prescribing the offending medication in the future. In severe cases, an allergic reaction can lead to anaphylaxis, a life-threatening condition that requires immediate medical attention. Always consult a doctor if you suspect a drug allergy.