Please note: This information was current at the time of publication but now may be out of date.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. 2004;70(4):703-704

What are allergy shots?

Allergy shots contain small amounts of the things that you are allergic to. These things are called allergens. The dose of allergen starts very low and is slowly increased over many weeks. The goal is to increase your immunity (resistance) to the allergens, and to reduce your allergy symptoms. When this happens, you can take less allergy medicine.

Who benefits from allergy shots?

Allergy shots may help you if you have problems with allergies, such as:

  • Itchy, runny, or stuffy nose (allergic rhinitis)

  • Itchy, watery, or red eyes (allergic conjunctivitis)

  • A life-threatening reaction to insect stings

What is the schedule for the shots?

Your doctor will decide the number of shots you will need. For the first six months, you will usually get shots once a week. During this time, the dose of allergen is a little bigger each week. If more than seven to 10 days have gone by since your last shot, the doctor cannot increase your dose. So, it is important not to miss any shots. Sometimes the build-up phase takes longer than six months.

Once you have reached your highest dose, you will be in the “maintenance phase.” In this phase, you will get shots every two to four weeks.

How long will I need to get shots?

You may have fewer symptoms in the first six months of treatment. You should start having fewer symptoms after being on a maintenance dose for one to two years. You will continue to get shots for three to five years. It takes this long to protect you from allergens.

What risks are there with allergy shots?

You may have redness, swelling, or pain at the site of the shot. These symptoms usually start 20 to 30 minutes after the shot and may not go away until the next day.

To make you feel better, put an ice pack on the shot site and take an antihistamine, like diphenhydramine (Benadryl is one brand name). Sometimes, the amount of your next dose will need to be changed.

If you have a reaction that is bigger than one and a half inches wide, you should tell your doctor. A reaction that lasts longer than 24 hours also should be reported to the doctor.

Life-threatening reactions are rare. These are serious reactions:

  • Sudden itching of the nose, eyes, throat, ears, or skin

  • Shortness of breath or wheezing

  • A lightheaded or dizzy feeling

  • Tightness in the chest

  • Hives or itchy palms

Serious reactions most often occur within 30 minutes after the shot. Any of these symptoms should be reported right away. The office where you get your shots can treat these reactions. The treatment will include a shot of adrenalin and an antihistamine. More treatment may be needed.

What can I do to help stop a reaction?

At each visit, tell the nurse any new information before you get the shot.

  • Report anything that happened after your last shot.

  • Report any new medicines you are taking.

  • Report any new medical problems or illnesses.

  • Report any flares of your allergies.

  • Report any flares of your asthma.

  • Report if you are pregnant.

Exercise increases your chance of having a serious reaction. You should not exercise for one hour before your shot or for two hours after the shot.

What are the benefits of allergy shots?

  • You might be cured of your allergies.

  • You may need less allergy medicine.

  • You may be sick less often and miss less work or school because of illness.

  • You may feel better in general.

  • The shots may stop children from getting other allergies.

  • The shots may stop children with allergies from getting asthma.

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