Are antihistamines vasoconstrictors

Antihistamines are not classified as vasoconstrictors; rather, they work by blocking the action of histamine, a substance in the body that can cause allergic symptoms. While histamine can lead to vasodilation and increased permeability of blood vessels, antihistamines help alleviate these effects, potentially leading to less swelling and redness. However, their primary function is to relieve allergy symptoms rather than directly inducing vasoconstriction.