Miles Weinberger, MD
Professor of Pediatrics
Allergy, Immunology, and Pulmonary 

The purpose of allergy shots is to decrease sensitivity to inhalant allergens. It is hoped that the decreased sensitivity will result in decreased respiratory symptoms. However, respiratory symptoms from asthma and rhinitis (nasal symptoms) will only improve to the extent that: 1) they are actually caused by the specific inhalant allergen for which injections are given, and 2) the allergic sensitivity is actually decreased by the series of injections. In actual fact, respiratory symptoms may not all be on an allergic basis, and the allergy shots are not always effective in decreasing sensitivity.

The ability of allergy shots to reduce allergic sensitivity appears to be greater for some allergens than for others. For example, there is less evidence that allergy shots are beneficial for mold sensitivity than there is for pollens. Your physician must weigh the evidence that allergy shots to the allergen suspected of causing a clinical problems can reduce sensitivity. Additionally, the judgment must also be made that there will be substantial clinical benefit if allergic sensitivity were reduced (remember, not all asthma is due to allergy) since allergy shots are an extensive and prolonged undertaking and are not completely without risk (allergic reactions can occur from the injections).

The procedure for allergy shots involves beginning with weekly injections of small amounts of dilute antigen and increasing the dose and concentration slowly over several months. Once a maximum dose is reached, a monthly maintenance schedule is established. This takes at least 4 months and often longer. Missed doses slow the procedure by preventing safe increases. Extended periods without injections require that the dose be reduced to assure safety.

Side effects of allergy shots relate to the possibility of an allergic reaction to the allergy shots. This happens in approximately 1% of injections. As long as this is treated promptly with an injection of epinephrine, the danger from the reaction is small. However, it is important that you wait in the doctor's office for at least 30 minutes after receiving each injection.

Assessment of benefit from allergy shots for inhalant allergens generally requires at least a 1 to 2- year trial. Failure to be convinced of substantial benefit indicates the allergy shots should be considered a treatment failure and be discontinued. If convincing benefit is apparent, then the allergy shots are continued until there is a 2-year period without any symptoms. Consideration is then given to discontinuing the allergy shots to see if the problem is in remission. However, there is always the possibility that symptoms suppressed by the allergy shots will return once they are stopped.

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