Anaphylaxis Treatment with Famotidine

Introduction to Famotidine Use

The American Academy of Allergy, Asthma, and Immunology recommends famotidine as second-line adjunctive therapy for acute allergic reactions, with a dose of 1-2 mg/kg (maximum 75-150 mg) intravenously or orally in the hospital setting, and it should not be used as monotherapy but only as adjunctive treatment to epinephrine 1, 2

For children, the recommended dose is 1-2 mg/kg per dose, with a maximum dose of 75-150 mg (oral or IV), as suggested by the American Academy of Pediatrics 1, 2, 4
For adults, the maximum dose is 75-150 mg (oral or IV), as recommended by the American College of Allergy, Asthma, and Immunology 1, 2
The American Academy of Allergy, Asthma, and Immunology also mentions ranitidine dosing as 50 mg in adults and 12.5-50 mg (1 mg/kg) in children, which can be diluted and given IV over 5 minutes 3

H2-antihistamine (ranitidine or famotidine) should be given twice daily for 2-3 days at discharge, alongside H1-antihistamines and corticosteroids, as part of post-discharge adjunctive therapy, as recommended by the National Institute of Allergy and Infectious Diseases 1, 2, 4

Epinephrine is the only first-line treatment for anaphylaxis, and intramuscular epinephrine 0.01 mg/kg (maximum 0.5 mg) must be given immediately, followed by famotidine as adjunctive therapy, as stated by the American Heart Association 1, 2
H2-antihistamines take significantly longer to work than epinephrine, which is why they cannot be relied upon for acute life-threatening reactions, as noted by the American Academy of Allergy, Asthma, and Immunology 3