The most commonly used treatments for allergies are over-the-counter and prescription drugs.

Antihistamines

Antihistamines comprise a broad class of drugs that help prevent the symptoms of allergies by blocking the inflammatory effects of histamine. These drugs do not prevent the release of histamine from mast cells, but they prevent histamine from interacting with other body cells and causing inflammation. First-generation antihistamines such as diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton) are available over the counter but these may tend to cause sleepiness. However, people react differently to different antihistamine medications: one person may get relief from their symptoms but experience sleepiness, while another person might have less sleepiness but also less symptom relief.

Newer generation antihistamines are non-sedating and may be available over the counter or by prescription. These include fexofenadine (Allegra), loratadine (Claritin, Alavert), and cetirizine (Zyrtec). Some of these antihistamines are now available with an added decongestant and go by names like Allegra-D, Claritin-D, and Zyrtec-D. Caution: these medications should not be combined, or mixed with alcohol. Avoid driving or using machinery while taking these medications.

Nasal sprays

Several types of nasal sprays are available that can alleviate the nasal congestion that accompanies allergic reactions. Nasal irrigation using warm saline (salt water) can clear out excess mucus and particulates while at the same time moisturizing the nasal cavities. You can use a fluid-filled syringe, a small squeeze bottle, or a neti pot. This technique can be difficult to get the hang of, but can really help with mild nasal congestion without using medications.

Antihistamine nasal spray such as prescription azelastine (Astelin) uses a small localized dose of histamine-blocking medicine delivered directly to the nasal passages. These medications tend to be less effective than nasal sprays that contain corticosteroids (see below).

Cromolyn sodium (NasalCrom) is available as an over-the-counter nasal spray that must be used several times a day. It helps relieve hay fever symptoms by preventing the release of histamine, but in order to be effective, it must be used before allergy symptoms begin.

Corticosteroid nasal sprays are some of the most powerful and effective medications for allergies because they work by inhibiting the immune system. Corticosteroids are hormones normally released in the body by glands called the adrenal gland to help you manage stress. Synthetic versions of these hormones can be inhaled to help control allergy symptoms. Examples include fluticasone (Flonase) and mometasone (Nasonex). These nasal sprays are often the most effective against outdoor allergies because of their powerful anti-inflammatory effect on the nasal tissue so they are often the first medication prescribed. Although these medications can start to work after a few days of treatment, you may not notice any improvement until after you’ve used them for a week or so. Nasal corticosteroids are a safe long-term treatment for most people.

Some over the counter nasal sprays include nasal decongestants that can offer temporary relief from nasal allergy symptoms such as Afrin, Dristan, and Neo-Synephrine. CAUTION: do not use these sprays for more than three days. They can cause “rebound congestion,” where the spray causes nasal tissue to swell and actually increases congestion over time, leading to a vicious cycle of increasingly more frequent use of the spray.

Nasal atropine sprays such as ipratropium bromide (Atrovent) are available with a prescription and may help relieve a severe runny nose by blocking the secretion of excess mucus. Nasal atropine is not effective for treating congestion, sneezing, or postnasal drip. Side effects are usually mild and may include nasal dryness, nosebleeds, and sore throat.

Oral corticosteroids

Corticosteroid medications in pill form, such as prednisone, are sometimes used to relieve severe allergy symptoms. Because the long-term use of oral corticosteroids can cause serious side effects such as infections, muscle weakness, and osteoporosis, they’re usually prescribed only for short periods of time.

Leukotriene modifiers

These drugs work by either blocking the production of or preventing the action of natural body molecules called leukotrienes. These molecules are released during an allergic reaction and are the cause of some of the symptoms of allergies such as excess mucus production. Leukotriene modifiers block this effect. These drugs are taken orally once or twice daily and are usually not as effective as corticosteroids at preventing allergy symptoms. Side effects of these medications include gastrointestinal problems and sleep disorders. Examples of leukotriene modifiers include montelukast (Singulair) and zafirlukast (Accolate).

Immunotherapy

Commonly called “allergy shots” or desensitization therapy, immunotherapy is the only medical treatment that offers prolonged relief from allergy symptoms. It involves subcutaneous (under the skin) injections of increasing concentrations of the allergens to which you are sensitive. Over time, your body will begin to make less IgE antibodies against these allergens and instead makes IgG antibodies, which do not trigger allergies. The effects of immunotherapy may only last for as long as the shots are being administered, or they may last for years longer. Talk to your doctor about how often these shots will need to be administered and how long you can expect the effects to last.