Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2011;83(5):622-623

What are allergy shots?

An allergy shot contains a very small amount of what you are allergic to (called an allergen). Common allergens include mold and pollen from grasses, ragweed, and trees. For example, if you are allergic to grass pollen, a small amount of the pollen is put into the shot.

How do the shots work?

Allergy shots help your body fight the allergen. When you get shots that contain the allergen, your immune system makes antibodies to the allergen. The next time you have contact with the allergen, these antibodies help block its effect. Because the antibodies block the way your body reacts to the allergen, your allergy symptoms become less severe. After many shots, you may start to get relief from your allergy symptoms. This relief will last for a long time.

What kind of allergies can be treated with shots?

Allergy shots work well for pollen allergies (also called allergic rhinitis or hay fever), eye allergies, bee-sting allergies, and some drug allergies. In some people, allergy shots can improve asthma symptoms.

People usually get these shots after they have tried other treatments that haven't worked. Other treatments include avoiding allergens and taking medicine, such as an antihistamine.

Can everyone get allergy shots?

No. Allergy shots may not be good for you if you have severe asthma or heart problems. You shouldn't get allergy shots if you take a beta blocker for heart problems. Children younger than five years also shouldn't get allergy shots.

You shouldn't start allergy shots if you are pregnant. If you have been getting allergy shots for some time and become pregnant, talk to your doctor. You may be able to continue the shots.

How do I know if I can try shots?

Your doctor will do a test to help figure out what is causing your allergy. A skin prick test puts tiny amounts of allergens onto your skin to see which ones you react to. Or, your doctor may decide to do a blood test.

How many shots will I have to get?

You will start getting shots one or two times each week. After about six months of weekly shots, your doctor will decide when you can start maintenance treatment. These shots are usually given just once each month, year round. You'll probably need to get monthly shots for three to five years. Then you may be able to stop getting shots.

Are allergy shots safe?

Yes, usually. Because the shots contain small amounts of an allergen, you might have an allergic reaction to the shot. A common reaction is swelling at the needle site.

Some people can also have severe, shock-like reactions to an allergy shot. This type of reaction is called anaphylaxis (ann-uh-fa-LAX-iss). Anaphylaxis is rare but very serious. If you get your shots on schedule (every week or every month), you're less likely to have this kind of reaction.

In case you have a bad reaction, your doctor will have you stay at the office for about 20 minutes every time you get your shot. That way, if you have a reaction, your doctor can give you something right away to stop it.

How soon after I get the shots will I start feeling better?

It usually takes six months or more of shots before you start feeling better. If you don't feel better after this time, talk with your doctor about another kind of treatment.

Where can I get more information?

Your doctor

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American Academy of Allergy, Asthma, and Immunology

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