Allergy Shots

Allergy shots may be a good treatment choice if:

• you are allergic to insect stings.
• you want to reduce long term use of allergy medication.
• allergic medications cause worrisome side effects
• allergic medications interact with other medications that you need to take
• medications do not control your symptoms well, and you cannot avoid the things that cause your allergic reactions.

Allergy shots can be used to control symptoms triggered by seasonal allergens, indoor allergens and insect stings. Allergy shots are not available for food allergies or chronic hives (urticaria).

Allergy shots can produce a reaction however if you get your shots regularly you are less likely to have a serious reaction. Taking an antihistamine medication before you get an allergy shot can reduce the risk of a local reaction but you have to check with your doctor to see if this is right for you.

It is also possible to get a severe reaction and this is scary but you will not be on your own as you will be observed in the doctor’s office for 30 minutes after each shot when the most serious reactions likely occur.

If you have a serious reaction after you leave do return to your doctor’s office or go to the nearest hospital

Most people do not react to allergy shots but they contain the substances that cause your allergies – so reactions are possible and can include:

• Local reactions – redness, swelling and itching around the site of injection. These typically occur within a few hours after the injection and soon clear up. They are more common.
• Systemic reactions – Here you may develop sneezing, nasal congestion or hives. More serious reactions may include throat swelling, wheezing or chest tightness. They are less common.
• Anaphylaxis – Rare but life-threatening reaction. Here you may have low blood pressure and trouble breathing. It often begins within 30 minutes of the injection, but sometimes starts later than that.

How you prepare

Before you are started on a course of allergy shots your doctor will use either a skin test or blood test to detect if the causes of your reactions are caused by an allergen and if so what specific allergens are responsible.

When you go for allergy shots do let your health care providers know if you feel unwell in any way. This is so important if you have asthma. You should also let them know if you had any symptoms after a previous allergy shot.

What you can expect

Allergy shots are given on a schedule that involves two phases:

• The build-up phase- generally takes three to six months. Typically shots are given one to three times a week. During the build-up phase, the allergen dose is gradually increased with each shot.
• The maintenance phase- generally takes three to five years or longer. You’ll need maintenance shots about once a month.

In some cases, the build-up phase is done more quickly which requires several injections of increasing doses during each doctor visit. This can decrease the amount of time you need to reach the maintenance phase and get relief from allergy symptoms, but also increases your risk of having a severe reaction.

You will need to remain in the doctor’s office for 30 minutes after each shot, in case you have a reaction.

Before the procedure

Before you are started on a course of allergy shots your doctor will use either a skin test or blood test to detect if the causes of your reactions are caused by an allergen and if so what specific allergens are responsible.

During the procedure

The allergy shots are given through the skin on the arm under aseptic conditions.

After the Procedure

After the shot, you may have a reaction. It can be local, systemic or anaphylactic which is life-threatening. 

Allergy symptoms will not stop overnight. They usually improve during the first year of treatment but the most noticeable improvement often happens during the second year. By the third year, most people are desensitized to the allergens contained in the shots- and no longer have significant allergic reactions to those substances.

After a few years of successful treatment, some people do not have significant allergy problems even after allergy shots are stopped. Other people need ongoing shots to keep symptoms under control.