Treatment of Hay Fever

Allergen Immunotherapy

Allergen immunotherapy (also called vaccine therapy or desensitization) has been available for approximately 100 years. The process involves the administration of gradually increasing quantities of specific allergens to persons with allergies until a dose is reached that is effective in reducing disease severity from natural exposure. The goal of treatment is to reduce responses to allergic triggers in the short-term and to decrease inflammatory response and prevent development of persistent disease in the long-term.

Allergen immunotherapy should be considered for people who:

• Experience moderate to severe allergy symptoms
• Require systemic corticosteroids
• Have inadequate response to nasal corticosteroids
• Have co-existing conditions such as asthma or sinusitis

Allergen immunotherapy should also be considered for those patients for whom the cost of immunotherapy will be less than the cost of long-term medications.

The allergens for which immunotherapy is known to be effective include:

• Hymenoptera venom (sawflies, wasps, bees, ants)
• Pollens
• Cat dander
• Dust mites
• Cockroaches
• Fungi

Allergy immunotherapy is not effective for atopic dermatitis or urticaria (hives) and cannot be used for food allergies because the risk of a severe allergic reaction (anaphylaxis) is too great.

"Allergy shots" are administered subcutaneously (injection under the skin) on a weekly basis in the medical provider's office. An observation period of 20-30 minutes after injection is mandatory to monitor for adverse reactions. The dose is gradually increased by the allergist to an optimal maintenance dose, which is then administered at intervals of 2 to 6 weeks. Typically, the maintenance concentration is achieved in 6 months however, people with a higher degree of allergen sensitivity may require a longer build-up phase. Within 6-12 months of treatment, hay fever symptoms usually begin to decrease. It is usually possible to discontinue treatment after about five years of injections. Approximately 33% of people treated with allergen immunotherapy are cured after treatment, another 33% experience a partial relapse, and the remainder will relapse completely. Those not cured may be helped by resuming the shots. It is important to follow up with your allergist regularly during treatment.

Another approach to allergy shots is called "rush immunotherapy." Patients spend several days receiving repeated shots to desensitize them against allergens, followed by earlier transition to the maintenance schedule. Studies have suggested that rush immunotherapy can be at least somewhat effective under certain circumstances, however, more studies are needed to demonstrate its safety and effectiveness. Currently, no allergen extracts are approved by the FDA for this approach.

Sublingual Immunotherapy

Allergen immunotherapy can also been given via sublingual (under the tongue) administration. This method is called sublingual immunotherapy (SLIT) or "allergy drops". This approach has been found to be easier for children, severe asthmatics, the elderly, and anyone who cannot tolerate allergy shots. SLIT has been available in Europe for decades - it is thought that as many as 50%-75% of allergy patients in Europe utilize this method for allergy immunotherapy. SLIT has only recently started to gain popularity in the United States, however, is not yet approved by the Food and Drug Administration (FDA).

SLIT works the same way as allergy shots, but is administered by placing a pre-determined amount of antigens under the tongue. Benefits include convenience (SLIT is administered at home once a day) and appears to be safer than injections with less risk of systemic reaction - there have been no known life-threatening anaphylaxis reactions with SLIT in over 30 years, and over 200 million doses in Europe. The World Health Organization (WHO) has endorsed sublingual immunotherapy as a viable alternative to injection therapy.

Sublingual immunotherapy with allergy drops can be given for both environmental allergies (i.e. hay fever, seasonal or perennial allergies) as well as for certain food allergies. The usual treatment regimen consists of three drops of each vial under the tongue daily. Approximately every three months, the dose is adjusted and the new vial(s) are picked up at the allergist's office. Like allergy shots, the complete immunotherapy treatment course averages about 3-5 years.

Currently, the option of sublingual immunotherapy has not been approved for coverage by health insurance. The cost of treatment averages about $25.00 for 1 vial and $50.00 for 2 vials per month.

Side Effects of Immunotherapy

While the most common side effect of allergy vaccines is redness and itching at the injection site, there is a risk of systemic reactions during immunotherapy, especially during the induction or "up-dosing" phase. Approximately 5-10% of people receiving immunotherapy have systemic reactions, which are moderate to severe in 1-3% of cases. This is why the 30 minute observation period following injection is required. Reactions include urticaria (hives), respiratory symptoms, and low blood pressure. There have also been rare instances of death from severe anaphylactic reactions. Anaphylaxis is a severe, systemic allergic reaction caused by the systemic release of histamine and other mediators. Symptoms include swelling of the throat (laryngeal edema), lower-airway obstruction and hypotension. Treatment of anaphylaxis involves prompt administration of epinephrine which should reverse the actions of histamine within minutes. This treatment can be followed by a histamine blocker and corticosteroids.

Patients should not be taking beta-adrenergic blocking drugs or angiotensin-converting enzyme (ACE) inhibitor medications when receiving immunotherapy because these drugs may mask early signs and symptoms of a severe reaction (anaphylaxis). Other people for whom immunotherapy is not suggested include those with chronic lung disease, unstable angina or history of myocardial infarction (heart attack), uncontrolled hypertension, and major organ failure.

Because a systemic reaction occurring during pregnancy may produce severe fetal hypoxia or precipitate premature uterine contractions, immunotherapy should not be initiated during pregnancy. However, immunotherapy can be maintained during pregnancy provided the woman is tolerating and benefiting from the injections. The immunotherapy dose should not be increased during pregnancy.