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A 31-year-old member asked:

How many milligrams of antihistamine can a person take at one time?

1 doctor answer2 doctors weighed in
Dr. Thomas Shen
Internal Medicine 29 years experience
Unclear: Different antihistamines have different potencies. 10 mg of Zyrtec is equivalent to 180mg of Allegra (fexofenadine). Mg doseage as in all medicines are drug specific. In regard to toxic levels, each has it's own known limit. However too much antihistamine can lead to deadly arrythmias/ Please use the recommended dose.

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Last updated Jun 16, 2018

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