Allergy medications help treat or prevent the symptoms associated with allergies. They may be recommended to a patient when other forms of treatment have failed. Usually, a physician will suggest lifestyle modifications to avoid the allergen. If this proves unsuccessful or is not practical, allergy medications (sometimes in combination with some lifestyle modifications) may be recommended.

Allergy medications are divided into two categories:

• Controllers. These drugs work to prevent allergy symptoms from appearing. They interfere with the process that causes inflammation, or prevent the release of the chemicals that trigger symptoms.
  
  
• Relievers. These drugs provide temporary relief once symptoms have appeared. They may be used alone to treat very mild allergies, or with controllers as a long-term treatment plan for moderate to severe allergies.

Some medications, such as antihistamines, work as both controllers and relievers.

The medication a physician recommends will depend in large part on the patient’s symptoms. Other factors physicians will consider include the patient’s overall health and medical history, the severity of the patient’s allergic condition, the patient’s tolerance for certain medications, the physician’s expectations for the course of the condition (i.e., whether this is an acute or more long term process) and the patient’s personal preferences.

Various drugs treat different aspects of an allergic reaction. The most popular medications include:

• Antihistamines. Medications that work as both controllers and relievers, antihistamines block the work of histamine, a chemical released during allergic reactions. Histamine contributes to symptoms such as hives, sneezing, runny nose and itchy eyes. Antihistamines attach to cell receptors – known as H1, H2 and H3 – and prevent histamine from doing the same. The histamine (which primarily does its work at the H1 receptor) has nowhere to go, short-circuiting the allergic process. Antihistamines typically are taken as pills, nasal sprays, eye drops and skin creams and sprays. 
   

  

• Decongestants. Relievers that treat symptoms of nasal congestion. During an allergic reaction, histamine opens blood vessels in the nasal passage and causes fluid to leak from them. This swells the tissues, narrowing the airway and causing the person to feel stuffy. Decongestants counter this effect by constricting blood vessels, reducing the swelling of nasal tissues and decreasing mucus production. Decongestants usually are available as pills, liquid or syrup, eye drops, nasal drops and nasal spray.
  
  
• Anti-inflammatories. Controller medications that inhibit allergic reactions and reduce nasal swelling. They usually are taken as a nasal spray. Three of the more popularly prescribed anti-inflammatories are:
  
  
• • Corticosteroids. Used to treat the most severe forms of allergic rhinitis (hay fever), they decrease inflammation in nasal passages during an allergic reaction. Corticosteroids mimic the behavior of cortisol, a hormone in the body that aids proper body function during stressful situations. This extra boost helps the body fight inflammation. Corticosteroids also can shrink nasal polyps. Corticosteroids generally are taken topically, or inhaled nasally or through the mouth. But they also can be found in pill form and as eye drops. When applied to the skin, these drugs relieve itchiness and prevent rashes from spreading. When placed into the eye as an eye drop, corticosteroids can relieve redness, tearing and itchiness.
    
    
  • Cromolyn sodium. The most common mast cell stabilizer, medications that prevent mast cells from bursting and releasing histamine and other chemicals known to cause the symptoms of an allergic reaction. Cromolyn sodium is used to relieve runny nose and sneezing but is not as effective as corticosteroids and cannot be used to treat nasal polyps. However, it has fewer side effects than corticosteroids. It comes in nasal inhaler, oral, eye and nasal spray (nonprescription) form.
    
    
  • Leukotriene modifiers. Usually prescribed to treat asthma but may also be prescribed for some people with allergies. Medications within this class have been approved in the United States as a controller drug used to prevent symptoms of allergic rhinitis. Some studies have indicated that these prescription drugs may be more effective when combined with antihistamines, thereby shutting down two major chemicals in airway constriction, histamines and leukotrienes.
    
    It should be noted that leukotriene modifiers have not been found to be as effective as inhaled corticosteroids, and that there is not yet a body of evidence to conclusively state that leukotriene modifiers are an effective means of treating allergic rhinitis by themselves.
    
    
• Bronchodilators. Medications that open the airway to relieve breathing problems such as shortness of breath, wheezing or chest tightness. They come in several forms, including pills, liquids, injections and inhalers. Some forms are only available by prescription while others are available over-the-counter.
  
  
• Antihistamine/decongestant combinations. Over-the-counter and prescription antihistamine/decongestant combination drugs also are available. This type of medication relieves all mild allergy symptoms a patient might experience.

Epinephrine may be recommended to reverse the symptoms of anaphylactic shock, a rare and severe allergic reaction that is potentially life-threatening. Epinephrine constricts blood vessels, prevents fluid leakage, opens the airways and raises blood pressure.  It also quickly relieves the itching and skin flushing that is part of most anaphylactic reactions. Epinephrine usually is injected in the thigh. Physicians recommend that individuals at risk for anaphylaxis use epinephrine at the first sign of this condition.

Anti-IgE antibodies are newer controller medications used to prevent allergy-related asthma attacks. Research into newer, alternate anti-IgE antibody treatments is ongoing and many of the long-term side effects of this type of therapy are still unknown.

While not medications, allergy shots (immunotherapy) are another form of allergy treatment. Low doses of an allergen are periodically injected into a patient over a period of months or years to increase the patient’s tolerance to the allergen. This reduces symptoms brought on by an allergic reaction. Typically, allergy shots are recommended after use of other medications has failed to tame symptoms, or to prevent cases of whole-body allergic reactions known as anaphylaxis.

Many allergy medications can be purchased over-the-counter at a pharmacy. Others must be prescribed by a physician. Patients should not take any medications without first consulting a physician.