Allergy shots

How Do They Work?

Allergy symptoms occur when your immune system tries to attack the allergen in the body. When this happens, your body creates mucus. This can cause bothersome symptoms in the nose, eyes, and lungs.

Allergy shots are also called "immunotherapy" since they work with the immune system. When a small amount of the allergen is injected into the body, the immune system makes an "antibody" that blocks the allergen from causing symptoms.

After several months of injections of a specific allergen(s) known to cause some of your symptoms, you may feel relief of some or all of your symptoms. The relief of symptoms can last several years. For some patients, allergy shots can prevent new allergies and help asthma symptoms.

Who Can Benefit from Allergy Shots?

People with well-controlled allergic asthma, allergic rhinitis, allergic conjunctivitis and insect bite sensitivity can benefit from targeted allergy shots. Patients with eczema (a skin condition) caused by dust mite allergy may also benefit from allergy shots.

Allergy shots are effective for these common allergens:

• Weed and tree pollen
• Grass
• Mold or fungi
• Animal dander
• Dust mites
• Insect stings

Adults, including the elderly, as well as children may receive allergy shots.

People with severe asthma or heart conditions are generally not good candidates for allergy shots. If you take medications, such as ACE inhibitors or beta blockers, you should discuss the risks of allergy shots with your doctor. Pregnant women should not begin allergy shots, but they may be able to continue allergy shot treatment that has already started.

Food allergies are not treated with allergy shots.

Getting Your Allergy Shots

Allergy shots are typically given in your doctor’s office about 1 - 3 times per week for 3 - 6 months. This is called the "build up" phase. Additional doses are given for 3 - 5 years every 4 - 6 weeks. This is called the "maintenance" phase. The shot is usually given in the upper arm area.

Keep in mind that many visits are needed to feel the full effects of this treatment. Your doctor will assess your symptoms on occasion to help decide when you can stop your allergy shot treatment.

Side Effects of Allergy Shots

An allergy shot may cause a reaction on the skin (such as redness, swelling, and itching) or a mild nasal stuffiness or runny nose.

Though rare, it can also cause a severe life-threatening allergic reaction called anaphylaxis. As a result:

• You may need to stay in your doctor’s office for 30 minutes after your shot to check for a reaction.
• You may be asked to take an antihistamine or other medication before your allergy shot appointment.

Reactions to allergy shots can be treated in your doctor’s office right away.

When to Call the Doctor

• You continue to have symptoms after several months of allergy shots.
• You have questions or concerns about the allergy shots and/or your symptoms.
• You are having trouble keeping appointments for your allergy shots.

Alternate Names

Allergy injections; Allergen immunotherapy

References

Sur DK, Scandale S. Treatment of allergic rhinitis. Am Fam Physician. 2010 Jun 15;81(12):1440-6.

Cox L, Nelson H, Lockey R, Calabria C, Chacko T, Finegold I, Nelson M, Weber R, Bernstein DI, Blessing-Moore J, Khan DA, Lang DM, Nicklas RA, Oppenheimer J, Portnoy JM, Randolph C, Schuller DE, Spector SL, Tilles S, Wallace D. Allergen immunotherapy: a practice parameter third update. J Allergy Clin Immunol. 2011 Jan;127(1 Suppl):S1-55.

Frew AJ. Allergen immunotherapy. J Allergy Clin Immunol. 2010 Feb;125(2 Suppl 2):S306-13. Review. PubMed PMID: 20176266.

Update Date: 10/27/2011

Updated by: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.