Immunotherapy (Allergy Shots)

Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU

Allergy shots (patient information)

Allergen immunotherapy was introduced by Leonard Noon 100 years ago and is the only disease-modifying treatment for allergic individuals (Allergy, 2012).

If you have allergies, you may be wondering if allergy shots are the best treatment for you. Here are the answers to some commonly asked questions.

What exactly is there in the allergy shots?

Allergen extracts are manufactured from natural substances, such as pollens, insect venoms, animal hair, and foods. More than 1,200 extracts are licensed by FDA.

How do allergy shots work?

After allergy testing, typically by skin testing to detect what allergens you or your child may react to, a health care professional injects the child with “extracts” - small amounts of the allergens that trigger a reaction. The doses are gradually increased so that the body builds up immunity to these allergens. Allergy shots work like a vaccine.

There are two phases of administration of allergy shots (immunotherapy): build-up and maintenance.

The build-up phase, ranges from 3 to 6 months, and involves injections with increasing amounts of the allergens. The frequency of injections is once or twice a week. Sometime more rapid build-up schedules are used.

The maintenance phase begins when the most effective dose is reached (maintenance dose). Once the maintenance dose is reached, there are longer periods between injections, typically every 2-4 weeks.

Who administers the allergy shots?

An allergist / immunologist, often referred to as an allergist, is the most qualified physician to test which allergy you have and tell you if allergy shots are right for you. The safest approach is to be seen and treated by a board-certified allergist. You can find an allergist here: http://www.acaai.org/allergist/Pages/locate_an_allergist.aspx

Who needs allergy shots?

Children or adults who don't respond to either over-the-counter (OTC) or prescription medications, or who suffer from frequent complications of allergic rhinitis, may be candidates for allergen immunotherapy - commonly known as allergy shots.

Allergy shots are recommended for patients with allergic asthma, allergic rhinitis/conjunctivitis and stinging insect allergy. They are not recommended for food allergies.

Before a decision is made to begin allergy shots, the following issues must be considered:

- Length of allergy season and the severity of your symptoms
- Whether medications and/or changes to your environment can control your allergy symptoms
- Your desire to avoid long-term medication use
- Time: allergy shots require a major time commitment. The duration is typically 3-5 years, and the shots often require brief clinic visits every 2-4 weeks.
- Cost: may vary depending on your state and insurance coverage

Immunotherapy for children is effective and well tolerated. It prevents the onset of new allergies. Allergy shots are the only treatment that prevents the progression from allergic rhinitis to asthma.

How effective are allergy shots?

According to the National Institute of Allergy and Infectious Diseases (NIAID), about 80-90% of people with allergic rhinitis will see their symptoms and need for medications drop significantly within a year of starting allergy shots.

How quickly will I feel better?

For many people, a decrease in symptoms is seen during the build-up phase, within 3-6 months. For others, it may take as long as 12 months on the maintenance dose.

How long should I stay on allergy shots?

Once the maintenance dose is reached (it takes 3-6 months), allergy shots are continued for 3-5 years. The decision to stop should be discussed with your board-certified allergist. Some people may have a permanent reduction of their allergy symptoms (the best outcome). Others may relapse and then a longer course of allergy shots can be considered.

What are the risks of allergy shots?

There are two types of adverse reactions that can occur with allergy shots.

Local reactions are common and are described as temporary redness and swelling at the injection site. This can happen immediately, or several hours after the treatment.

Systemic reactions are not common, and are usually mild and respond quickly to medications. Signs of a systemic reaction include increased allergy symptoms such as sneezing, stuffy nose or hives. Rarely, a serious systemic reaction called anaphylaxis (an-a-fi-LAK-sis) can develop, with swelling in the throat, wheezing, a feeling of tightness in the chest, nausea or dizziness. This reequires treatment with epinephrine (EpiPen).

Most systemic reactions develop within 30 minutes of giving allergy shots. You should you wait in your allergist office for 30 minutes after your injections.

Is there an alternative to allergy shots such as drops, etc.?

Some doctors are buying extracts licensed for injection and instructing the parents to administer the extracts using a dropper under the adult or child’s tongue. While FDA considers this the practice of medicine (and the agency does not regulate the practice of medicine), parents and patients should be aware that there are no allergenic extracts currently licensed by FDA for oral use.

Can you treat food allergy with allergy shots?

Allergy shots are never appropriate for food allergies. However, it is common to use extracts to test for food allergies so the child or adult can avoid those foods.

References

Allergy Immunotherapy, Allergy Shots. ACAAI.
Allergy Relief for Your Child - FDA Consumer Info.
Allergy Shots: Tips to Remember. AAAAI.
Allergen-specific immunotherapy. Allergy, Asthma & Clinical Immunology 2011, 7(Suppl 1):S5.
Image source: Pollen from a variety of common plants. Dartmouth Electron Microscope Facility, Dartmouth College.

Published: 09/28/2011
Updated: 01/28/2012