Allergic Reactions and anti-histamine dosing

Allergic reactions can range from hives to life-threatening reactions like anaphylaxis. Allergic reactions can be frightening.

  • A mild allergic reaction is limited - such as hives. This can be treated with a over-the-counter anti-histamine. 
    • Cetirizine: Dosing, Cetirizine (aka Zyrtec) is a modern anti-histamine. If specifically targets the receptors that cause allergies. It lasts 24 hours. It only causes drowsiness in about 10% of people. It does not enter the brain. This is my recommended anti-histamine.
    • Diphenhydramine: Dosing. Diphenhydramine (aka Benadryl) is a old anti-histamine. It targets other receptors than those causing allergies and also crosses into the brain. Because of this it has many more side-effects than cetirizine. It causes drowsiness in most children. In a minority of children it causes extreme hyperactivity. It also has effects on the heart - causing increased heart rate. It also needs to be re-dosed every 6 hours. As a result I do not recommend this medication. But in case it is all you have on hand I provide dosing above. 
  • Anaphylaxis is a allergic reaction that effects the whole body. As a result it effects multiple organ systems. For example, hives plus vomiting or hives plus trouble breathing or swelling of the mouth. If your child has signs of anaphylaxis 911 should be called. 
    • If you have a epinephrine auto-injector that can be used. For a child 30-60 pounds you use a 0.15 mg auto-injector and for those over 60 pounds you use a 0.3 mg auto-injector. Today there are multiple generic auto-injectors (CVS one, Mylan one, Adreniclick) so there is no need to pay a pricey co-pay for a brand-name one. 
    • If you child has anaphylaxis an Allergy Action Plan should be provided by your doctor to the child's school and other organized activities. 

Leave a Comment

Your email address will not be published. Required fields are marked *