Allergy shots (immunotherapy) for asthma

Treatment Overview

Allergy shots (immunotherapy) are a treatment in which small doses of substances to which you are allergic (allergens) are injected under your skin. Over time, your body may become less responsive to the allergens, which means you may have fewer symptoms.

Allergy shots are given after careful skin testing for an allergy. During initial treatment, allergy shots are given once or twice a week.

• At first, a small amount of allergens is used. The amount of allergen injected is increased slightly each time, unless you have a serious allergic reaction. After 4 to 6 months of weekly shots, the dose will contain an optimal amount of allergen. This is called the maintenance dose.
• After reaching maintenance, you get the same dose in shots every 2 to 4 weeks for another 4 to 6 months.
• While getting allergy shots, you need to see your doctor to be checked every 6 to 12 months. After 3 to 5 years of getting allergy shots, you and your doctor may need to make the decision to stop allergy immunotherapy or to continue. Many children who are helped by allergy shots stop taking them after 3 to 5 years. But these children often continue to benefit from having received the shots.¹

This information is for people with asthma. For complete information on allergy shots, see the topic Allergic Rhinitis.

What To Expect After Treatment

You receive allergy shots in your health professional's office. You will stay in the office for a short time after getting an allergy shot to be watched for possible life-threatening reactions (anaphylaxis) to the injected allergens.

Redness and warmth at the shot sites are common and go away after a short period of time.

Why It Is Done

Allergy shots may be used to help treat asthma if:²

• It is clear that you have asthma symptoms when exposed to an unavoidable allergen (allergic asthma).
• Symptoms occur all year long or during a large part of the year.
• It is difficult to control symptoms with medicine alone because medicines have not prevented symptoms, you've needed several medicines, or you do not want to take the medicine indefinitely.

How Well It Works

Allergy shots may be effective in treating asthma that is caused by an allergen and can reduce asthma symptoms and medication requirements.³

• The shots reduce symptoms in people allergic to pollens, animal dander, dust mites, mold, and cockroaches.¹
• Allergy shots may be effective for 3 years or longer after the shots are stopped.¹
• But how much you benefit from allergy shots compared to other asthma treatment is not clear.³

Risks

Allergy shots are safe if the shots are given correctly. Redness and warmth at the shot site are common. Overall body (systemic) reactions such as hives, asthma symptoms, and low blood pressure are not common. But people with asthma may be at increased risk for a severe reaction (anaphylaxis) to the shots and, possibly, death. You should have your asthma well controlled before receiving allergy shots.

Because of the possibility of anaphylaxis, the shots are given in a health professional's office where emergency care can be provided if needed. Most reactions to allergy shots occur 20 to 30 minutes after the injection. You should stay at your health professional's office for at least this amount of time.

You must report any delayed reaction to an allergy shot. Late reactions can happen any time within 24 hours after a shot. Reactions may be local (such as a large, red or raised area around the site) or overall body reactions (such as trouble breathing).

What To Think About

• Children younger than 2 should not have allergy shots. Children ages 3 to 4 may find it difficult to receive many shots over a long period of time. Talk with your health professional about whether allergy shots are suitable for your child.
• Older adults may be taking medicines or have other medical conditions that may increase the risk of a severe reaction to allergy shots.
• Pregnant women who are already taking allergy shots may continue them. But it is not recommended that allergy shots be started during pregnancy.
• Allergy shots take 3 to 5 years to complete and are expensive. It may take up to 1 year for allergy symptoms to improve. During your treatment, your health professional should evaluate you at least once every 6 to 12 months.

Allergy shots should not be used when you:

• Have had a recent heart attack, unstable angina, or other heart conditions or are taking beta-blockers.
• Are unable to communicate (can't tell your health professional about reactions to shots). Most health professionals do not give allergy shots to children younger than 5.
• Have an immune system disease such as AIDS. People who have immune system diseases such as systemic lupus or multiple sclerosis should be evaluated individually.

The possibility of giving doses of allergens under the tongue (sublingual) instead of by injection is being studied.

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Author:	Maria G. Essig, MS, ELS	Last Updated: March 22, 2007
Medical Review:	Michael J. Sexton, MD - Pediatrics Harold S. Nelson, MD - Allergy and Immunology
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