Antihistamines block histamine, which contributes to mild allergic symptoms such as hives and itching. However, anaphylaxis involves multiple chemical pathways beyond histamine alone, including the release of substances that cause sudden, severe airway swelling, dramatic drops in blood pressure, and respiratory failure. These effects develop within minutes and cannot be reversed quickly enough by antihistamines, which take too long to act. Adrenaline (epinephrine) acts within seconds, reversing airway swelling, raising blood pressure, and opening the airways. It is the only medication fast enough to treat anaphylaxis safely. Delay in giving adrenaline is the most common preventable cause of death from anaphylaxis.
Written by Dr. Nayan Mani Deka, MBBS (Gauhati Medical College, 2003), MD Paediatrics (GMCH Gauhati, 2008), Diploma in Allergy and Asthma (CMC Vellore), Certified PALS, APLS, NSSK, Consultant Paediatrician, Asthma Allergy Specialist and Immunotherapist, Pratiksha Rainbow Children's Hospital, VIP Road, Borbari, Guwahati, Assam 781036. Phone: +91 9436732863 / +91 6000714825.
