How Do Ophthalmic Antihistamines/Decongestants Work?

Ophthalmic antihistamines/decongestants are a combination of antihistamines and decongestants, which work in different ways to relieve eye allergy symptoms such as:

• Tearing
• Redness
• Swelling
• Itching

Ophthalmic antihistamines block the release of histamine by mast cells in the eye in response to allergens. Mast cells are a type of immune cells and histamine causes the symptoms of inflammation from an eye allergy. Mast cells are found all over the body, and in the eye, they are abundant in the conjunctiva, a clear membrane that covers the eyes and the inner surfaces of eyelids.

Ophthalmic decongestants are a class of medications known as alpha-adrenergic agonists. Alpha-adrenergic agonist drugs stimulate the activity of protein molecules known as alpha adrenergic receptors on smooth muscles of blood vessels and make them contract. The constriction of blood vessels reduces redness and irritation in the eyes.

Ophthalmic antihistamines/decongestants are solutions that are topically administered in the eye to relieve symptoms of allergic conjunctivitis. Allergic conjunctivitis is inflammation of the conjunctiva caused by a reaction to allergens such as pollen, dust, dander and mold spores.

Side effects of ophthalmic antihistamines/decongestants may include the following:

• Stinging and tingling sensation
• Dilation of pupils (mydriasis)
• Redness of eyes (ocular erythema)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of some ophthalmic antihistamines/decongestant ophthalmic eye drops include:

Naphazoline hydrochloride/pheniramine maleate (Naphcon-A, Opcon-A, Visine) - available over the counter

Naphazoline is an ophthalmic alpha-adrenergic agonist and pheniramine is an antihistamine.