Definitions

1. noun

A chemical compound derived from histidine, involved in immune response and allergic reactions, and produced by the body’s immune system.

“The doctor administered an antihistamine to alleviate the patient’s symptoms of an allergic reaction.”

2. verb

To cause an allergic reaction or to trigger an immune response.

“The pollen from the nearby flowers caused histamine to be released in her body, triggering her allergic symptoms.”