Please note: This information was current at the time of publication but now may be out of date.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. 

brand logo

Am Fam Physician. 1998;57(8):1897-1898

See related article on immunotherapy.

What are allergy shots?

An allergy shot has in it very small amounts of the substance that you are allergic to (called an allergen). Things that cause allergies are called “allergens.” Common allergens include mold and pollen from grasses, ragweed and trees. For example, if you are allergic to grass pollen, a small amount of grass pollen will be put into the shot.

How do allergy shots work?

Allergy shots help relieve allergy symptoms by changing the way your body reacts to the allergen that causes your allergy. When you get shots of the allergen, your body starts making antibodies that fight against the allergen. These antibodies help block the effects of the allergen the next time you have contact with it. Because the antibodies block the way your body reacts to the allergen, your allergy symptoms become less severe. After many allergy shots, you might start to get relief from your allergy symptoms. This relief will last for a long time.

What kind of allergies can be treated with allergy shots?

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

Usually people get allergy shots after they have tried other treatments that haven't worked. Other treatments include avoiding the things that make you have allergy symptoms and taking medicine, like an antihistamine, to prevent and relieve your allergy symptoms.

Can everyone get allergy shots?

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

Allergy shots shouldn't be started when a woman is pregnant. But if a woman has been taking allergy shots for some time and becomes pregnant, she can continue taking her allergy shots. Talk to your doctor about taking allergy shots while you are pregnant.

What will happen if my doctor and I choose allergy shots to treat my allergy?

Your doctor will first do skin testing or blood testing to try to find out what is causing your allergy. Your doctor needs to know what allergen bothers you because your shots will contain small amounts of that substance.

How many shots will I have to get?

Quite a few. 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. Maintenance shots are usually given just once each month, year round. You'll need to get monthly allergy shots for three to five years. Then you can stop having shots.

Are allergy shots harmful?

Usually allergy shots are very safe. But because allergy shots contain small amounts of the allergen you're allergic to, you might have an allergic reaction to the shot itself. One kind of allergic reaction is swelling at the place where the shot is given.

People can also have severe, shock-like reactions to an allergy shot. This type of reaction is called “anaphylaxis” and is very serious. But this problem rarely happens. 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 to the shot, your doctor can give you something right away to stop it.

How long after I start taking the allergy shots before I feel better?

It usually takes six months or more of allergy shots before you start feeling better and notice relief of your allergy symptoms. If you don't feel better after this much time, you should probably talk with your doctor about another kind of treatment for your allergies.

Continue Reading

More in AFP

Copyright © 1998 by the American Academy of Family Physicians.

This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP.  See permissions for copyright questions and/or permission requests.