antihistamines in anaphylactic shock

Antihistamines in anaphylactic shock

• antihistamines are not recommended as part of the initial emergency treatment for anaphylaxis
• antihistamines have no role in treating respiratory or cardiovascular symptoms of anaphylaxis
• antihistamines can be used to treat skin symptoms that often occur as part of allergic reactions including anaphylaxis
  • their use must not delay treatment of respiratory or cardiovascular symptoms of anaphylaxis (using adrenaline and IV fluids)

Antihistamines can be helpful in alleviating cutaneous symptoms (whether these are due to anaphylaxis or non-anaphylaxis allergic reactions), but must not be given in preference to adrenaline to treat anaphylaxis. In the presence of ongoing Airway/Breathing/ Circulation problems of anaphylaxis, give further IM adrenaline and seek expert advice.

Once a patient has been stabilised, use a non-sedating oral antihistamine (e.g. cetirizine) in preference to chlorphenamine which causes sedation.

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Reference:

• Emergency treatment of anaphylactic reactions.Guidelines for healthcare providers.Working Group of the Resuscitation Council (UK) 2021