In this video, Dr Akshay Chhallani, Lead & Sr Consultant Critical Care and Medical Advisor, Apollo Hospitals Navi Mumbai explains what to do when someone has an allergic reaction. An allergic reaction occurs when the immune system overreacts to a harmless substance, such as pollen, food, or medication. Symptoms can include itching, swelling, rash, and difficulty breathing. Severity ranges from mild to life-threatening (anaphylaxis). Immediate treatment, often with antihistamines or epinephrine, is essential for severe reactions.