(Desensitization; Hyposensitization; Immunotherapy)
Type of Medication
Medication administered as an injection just under the skin to help decrease allergic reactions.
What Allergy Shots Are Most Frequently Prescribed For
Allergy shots don't work on all allergies or on all people with allergies. For example, they're not effective for food allergies .
Allergy shots should be considered for patients with severe symptoms that are difficult to control with medications (eg, Allegra , Claritin , inhaled corticosteroids, Singulair ) and when other forms of treatment have failed.
How Allergy Shots Work
Allergy shots decrease your sensitivity to allergens by exposing you to increasingly larger doses of the allergens to which you are allergic. An allergen is a substance that can produce an allergic, or hypersensitive response, often called an allergy attack. Pollen, dust mites, and mold spores are common allergens.
First, your doctor will use skin or blood tests to determine what you are allergic to. Then, a shot is made from small amounts of these specific allergens. With repeated shots, your body becomes less sensitive to these allergens, causing you to have a less severe allergic reaction or none at all.
It takes at least six months of regular shots before you notice relief of your allergy symptoms.
Precautions While Using These Medicines
Allergy shots should not be taken under these conditions:
- Severe asthma that is not controlled with medication
- Heart problems
- Taking a beta-blocker for heart problems
- Children under age five
Discuss pregnancy with your doctor.
Women who are pregnant should not begin allergy shots. However, if a woman has been receiving allergy shots for some time when she becomes pregnant, she may be able to continue.
Discuss other medications.
Tell your doctor if you are taking or plan to take any medications, including over-the-counter drugs, for both allergic and nonallergic conditions. Your allergy shots may affect the use of other medications.
Continue other measures.
Allergy shots can greatly reduce allergy symptoms, but are not a guaranteed cure. Therefore, you should continue to avoid known allergens while receiving shots.
Allergy shots are given year-round. For the first six months, you will get one to two shots per week. Then, a maintenance dose is injected once a month. You'll receive these monthly shots for three to five years. After this time, you may be able to stop shots completely.
Possible Side Effects
Allergy shots are usually safe. However, because they contain a small amount of an allergen, there is a risk of an adverse reaction. This may be as mild as swelling and redness at the site of the shot, which can last for 1-3 days. However, a serious, and life-threatening reaction called anaphylaxis or anaphylactic shock can occur. Such a reaction is very rare. Having your shots on a regular schedule decreases the risk of anaphylaxis.
You will receive your shot in a doctor's office and you will be asked to wait 20 minutes after the shot before leaving. If a bad reaction occurs, the medical personnel will be able to treat you immediately.
An alternative treatment to allergy shots (immunotherapy) is sublingual immunotherapy (SLIT) that does not require administration of an injection. Instead, a small amount of a liquid is given under the tongue. It eliminates the need for weekly or monthly doctor visits. This method is not as popular as the injections, but it has been gradually gaining acceptance in the US. In Europe, it has been successfully used for many years. Most insurance plans, however, do not cover it, and the cost can be substantial (on average $100 per month). Additionally, only few allergy specialists administer SLIT, and in some areas, of the country this method may not be easily available.
American College of Asthma, Allergy, and Immunology
Garcia-Marcos L, Carvajal Uruena I, Escribano Montaner A, et al. Seasons and other factors affecting the quality of life of asthmatic children. J Investig Allergol Clin Immunol. 2007;17:249-256.
Garcia-Marcos L, Lucas Moreno JM, Garde JG. Sublingual specific immunotherapy: state of the art. Inflamm Allergy Drug Targets. 2007;6:117-126.
Jacobsen L, Niggemann B, Dreborg S, et al. Specific immunotherapy has long-term preventive effect of seasonal and perennial asthma: 10-year follow-up on the PAT study. Allergy. 2007;62:943-948.
Last reviewed August 2007 by Marcin Chwistek, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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