Most allergy treatments are designed to relieve symptoms of allergic reactions that have already occurred. However, a growing number of therapies have been successful at allergy symptom prevention. The goal of such treatments is one or more of the following:

• Prevent the onset of symptoms
• Lessen the frequency of reactions
• Lessen the severity of symptoms resulting from a reaction

Allergy shots (immunotherapy) are the only treatment currently available for preventing allergy symptoms over a long period of time. By using this method, an individual can become gradually desensitized to a specific allergen (e.g., a specific food, pollen, latex).

Allergy shots involve the injection of small, diluted doses of a specific allergen into a closely monitored individual. These shots continue at regular intervals (first weekly, then less frequently), and with a slightly higher dose of the allergen, for a period of several years. Eventually, the allergic individual builds up a tolerance to a specific allergen. At this point, the person does not experience the same degree of allergic reaction after coming into contact with that allergen.

Allergy shots may be inconvenient and are not universally effective. Therefore, these treatments are generally reserved for individuals who cannot use drug treatments or cannot avoid their allergen. Allergy shots are not effective at treating some types of allergies (e.g., food allergies).

Aside from allergy shots, there are a growing number of treatments effective at preventing allergies and allergy symptoms. These are primarily medications, including:

• Leukotriene modifiers. Medications used to prevent both nasal allergy symptoms and asthma-related symptoms. This form of treatment effectively disrupts the leukotrienes that the immune system produces during an allergic reaction. Leukotrienes are often involved with the constriction of airways in the lungs.
  
  Leukotriene modifiers are effective when used prior to an allergic reaction because they work to disrupt a specific chemical process in the allergic cascade, preventing some types of leukotriene from forming in the body. While these medications are primarily used in the prevention of asthma-related symptoms, some forms are finding increased use in the prevention of allergic reactions. They are taken orally, in pill form, daily or several times daily.
  
  
• Antihistamines. Medications that block the histamines that cause the majority of symptoms associated with allergies. Histamines are released into the bloodstream during an allergic reaction. When antihistamines are present in the bloodstream, the histamines are still released. However, they are blocked from carrying out their normal functions. Taking this medication prior to being exposed to an allergen can completely prevent the onset of symptoms. In other cases, the severity of symptoms is reduced. Antihistamines are available as pills, liquids, nasal sprays and eye drops.
  
  Individuals suffering from hives, allergic conjunctivitis or allergic rhinitis (hay fever) can take antihistamines before coming into contact with an allergen to reduce the symptoms associated with these conditions. For best effects, an antihistamine should be taken 3 to 5 hours before coming into contact with an allergen – or on a regular basis. Because they can effectively prevent allergy symptoms, some people take antihistamines daily. While antihistamines can effectively block the symptoms associated with many allergies, the drugs may not be effective at treating some serious allergies (e.g., food allergies).  
  
  
• Corticosteroids. Medications used to reduce the inflammation associated with symptoms such as nasal stuffiness, sneezing and runny nose. Also known as steroids, corticosteroids work by enhancing the body’s ability to counteract the swelling, inflammation and mucus secretions caused by an allergic reaction. They are available as nasal sprays, inhalers, pills, topical creams and by injection.
  
  Corticosteroids are most effective at reducing allergy symptoms when taken on a daily basis – even when symptoms are not present. This medication often requires one to two weeks of use before reaching its full effect.
  

• Mast cell stabilizers. Medications effective at treating mild or moderate inflammation in the bronchial tubes as well as sneezing, watery eyes and congestion. Mast cell stabilizers prevent mast cells from releasing histamine and other chemicals that can cause allergy symptoms. This medication has fewer side effects than antihistamines. However, they take more time to work, require more doses and may not be as effective in relieving symptoms. Available as a nasal spray, in prescription metered-dose inhalers or as eye drops. This type of treatment is available both over-the-counter and as a prescription.
  
  
• Anti IgE antibody. These medications are used to reduce asthma and allergy reactions. The drug interferes with the immune system’s release of histamine by blocking IgE antibodies from binding with mast cells. Available only by prescription, the drug is given through an injection every two to four weeks. It is only Food and Drug Administration (FDA) approved for certain patients with asthma.