The American Academy of Allergy, Asthma, and Immunology (AAAAI) reports that allergy symptoms affect an estimated 40 to 50 million U.S. residents each year. Some substances such as pollen and dust can cause an exaggerated response in extremely sensitive individuals, resulting in excess tears and mucus. Symptoms can include itching, redness, burning, swelling and blurred vision. Allergy medications offer palliative relief to patients suffering from allergy symptoms.
Antihistamines
The main culprits of allergic responses are a special set of cells released by the immune system, called "mast cells." When exposed to an allergen, mast cells activate a histamine release in sensitized individuals. Allergy symptoms appear when the histamine released attaches to receptors in the body, causing them to increase in size. Antihistamines work by blocking histamine and their ability to cling on to receptors. In the case of eye allergies, antihistamines protect receptors in the conjunctiva which aid in the prevention of redness, itching, secretion changes, and all other symptoms of discomfort that histamine can cause. Although available in tablets, antihistamines eye drops offer quicker relief and provide more moisture. The University of Maryland Medical Center lists headache, drowsiness and mild burning as potential side effects.
Decongestants
Decongestants can also soothe allergy symptoms. During a reaction, blood vessels in the eyes can become aggravated causing increased redness and decreased moisture. Since decongestants only reduce redness and swelling, antihistamines should be taken as well for optimal benefit. Although available in pill, nasal and liquid form, decongestant eye drops extend a greater benefit. The Mayo Clinic cautions that potential side effects can include persistent redness and blood vessel damage if overused. Individuals with a history of high blood pressure and glaucoma should not take decongestant eye drops.
Corticosteroids
Corticosteroid medications treat and prevent inflammation caused by allergies. Corticosteroids mimic natural steroid chemicals found in your body, and if prescribed in doses greater than the body's normal level, they suppress inflammation. Although available in a variety of forms, corticosteroid eye drops treat symptoms such as itchy, red, watery eyes. Use of all corticosteroid medication should be supervised by the prescribing provider. The Mayo Clinic lists glaucoma, eye infections and cataracts as potential side effects.
Mast-Cell Stabilizers
During an allergic reaction, mast-cell stabilizers counter the release of histamine from the mast cells. Mast-cell stabilizers are available in different forms including eye drops that specifically treat red and itchy eye symptoms. The most effective eye drops are available by prescription as the over-the-counter formulas can have a prolonged onset of action. Optimal results are achieved when used prior to exposure with an allergen. According to the Mayo Clinic, mast-cell stabilizer eye drops exhibit no significant side effects.
