Allergy medications serve two purposes. Doctors at the Mayo Clinic report that allergy medications block the chemicals that cause allergy symptoms or reduce the body's reaction to the allergens. Allergy medicine comes in a variety of forms, from pills and nasal sprays to eye drops, liquids, cream and injections. Allergy medications are available over-the-counter or with a doctor's prescription.
Antihistamines
Antihistamines block the chemical histamine that the body releases in response to allergens. Oral antihistamines in the form of pills or syrup help to reduce swelling of the sinuses, runny nose and watery, scratchy eyes. Over-the-counter brands, such as Claritin and Zyrtec, contain loratadine and prescription brands like Allegra are made with fexofenadine. Side effects of antihistamines include dry mouth and grogginess. Older antihistamines, such as Chlor-Trimeton and Benadryl, contain ingredients that cause even more pronounced drowsiness. Nasal sprays with antihistamines work more directly on nasal symptoms. such as sneezing, post nasal drip and runny nose. While nasal sprays also can cause drowsiness, they also are known to cause headache, fatigue and dizziness. Nasal sprays also can cause a bloody nose, sore throat and nausea. Antihistamines in the form of eye drops are used to treat itchy eyes that may be red and swollen. Eye drops can burn or sting and can irritate eyes when wearing contacts.
Decongestants
Decongestants provide quick, temporary relief from allergy symptoms. Many oral decongestants are available over-the-counter. Some over-the-counter brands combine decongestant ingredients with antihistamines. Decongestants taken orally in pill or liquid form can cause irregular heartbeat, dizziness and irritability. Other side effects include insomnia, headaches and elevated blood pressure. While nasal decongestants can relieve sinus symptoms, they also can cause burning and sneezing. Rebound congestion is possible after patients stop taking nasal decongestants. Decongestant eye drops, whether used alone or in combination with antihistamines, can damage the eye if used too much. Doctors at the Mayo Clinic recommend minimal use of eye drops to relieve severe allergic reactions.
Corticosteroids
Corticosteroids, most of which require a prescription, are used to prevent allergic reactions and to reduce the symptoms of allergies. One example of corticosteroids often prescribed is prednisone, which can treat severe allergic reactions of all kinds. Doctors prescribe prednisone for short periods of time because long-term side effects can include muscle weakness and glaucoma. Nasal sprays containing corticosteroids usually have a bitter taste and smell and can cause additional nasal irritation. Asthma symptoms are treated with inhalation corticosteroids and have few side effects, but could cause a mouth infection, cough or headache. Corticosteroid skin creams are used to treat allergic reactions on the skin, such as rashes and lesions. Creams come in both over-the-counter and prescription strength versions. They can relieve itching and clear up symptoms. Side effects can include skin discoloration or mild irritation.
