Lahey Health is now part of Beth Israel Lahey Health

by Cornel J


Allergen immunotherapy uses tiny doses of an allergen to decrease the body’s reaction to it. It includes:

  • Subcutaneous immunotherapy (SCIT)—injected under the skin
  • Sublingual immunotherapy (SLIT)—pills or drops under the tongue

In some people, treatment can lead to complete relief from symptoms within 6 months. For others, symptoms may only be reduced or not changed at all.

Reasons for Procedure

An allergen is any item in the environment that can cause a reaction in some people. An allergy is an abnormal response to those allergens.

This therapy gives the body small doses of the allergen over a period of time. It may lower or stop the body’s reaction to the allergen. It may also reduce or end the need for allergy medication. It is most effective for:

  • Life-threatening reaction to insect stings
  • Severe hay fever
  • Animal allergies that don’t respond to medication

It is less effective for people who have multiple allergies or for food allergies.

Insect Bites
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Possible Complications

Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:

  • Skin redness, swelling, and itching
  • Sneezing
  • Nasal congestion
  • Hives
  • Infection at the injection site
  • Lightheadedness

Rarely, complications may also include:

  • Swelling in the throat
  • Wheezing or tightness in the chest
  • Nausea

Before your procedure, talk to your doctor about ways to manage factors that may increase your risk of complications such as:

What to Expect

Prior to Procedure

An allergy specialist will do allergy tests to find which allergens are causing the problem. This may involve skin prick tests and blood tests. This information will be used to choose which allergens and doses should be used.

Tell your doctor about any medications, herbs, or supplements that you take.

Certain medications, such as beta blockers, may cause complications during the procedure or recovery. These medications may need to be stopped up to one week before the procedure.


Anesthesia is not needed.

Description of the Procedure

The allergen will be delivered in one of 2 ways:

  • Subcutaneous immunotherapy (SCIT): A needle will be filled with a dose of the allergen. Your arm will be cleaned. The injection will be given under the skin of your arm.
  • Sublingual immunotherapy (SLIT): Tablets or drops containing the allergen are placed under your tongue for 1-2 minutes.

You will be put on a treatment schedule. Treatment starts with a build-up phase where the amount of allergen is slowly increased. The maintenance phase is next where the dose will stay the same, but there may be fewer treatments.

Treatment will need to be repeated at regular intervals for 3-5 years.

How Long Will It Take?

A few minutes

Will It Hurt?

You will feel a stinging if your allergen immunotherapy is being given by injection.

Post-procedure Care

At the Care Center

Right after the procedure, the staff will:

  • Place a bandage over any injection site
  • Monitor you for an allergic reaction to the allergen
  • Discuss what to expect

You will need to stay for at least 30 minutes to be monitored for an allergic reaction.

At Home

It will take some time before the body’s reactions change to the allergens. It is important to still take precautions for severe allergies.

If treatment is not effective, it may be due to the dose that is used, other allergens, or high levels of the allergen in your environment.

Call Your Doctor

Call your doctor if any of these occur:

  • Signs of infection, including fever and chills
  • Redness, swelling, increasing pain, excessive bleeding, or any discharge from an injection site
  • Skin redness, swelling, and itching
  • Hives
  • Difficulty breathing
  • Nausea
  • Lightheadedness

If you have an emergency, call for medical help right away.


American Academy of Allergy, Asthma, and Immunology 

Kids Health—Nemours Foundation 


Allergy Asthma Information Association 

Health Canada 


Allergy shots. Kids Health—Nemours Foundation website. Available at: Updated April 2014. Accessed January 17, 2017.

Allergy shots (immunotherapy). American Academy of Allergy, Asthma, and Immunology website. Available at: Accessed January 17, 2017.

Allergy shots (subcutaneous immunotherapy). American College of Allergy, Asthma, and Immunology website. Available at: Accessed January 17, 2017.

Immunotherapy. Allergy UK website. Available at: Updated June 2013. Accessed January 17, 2017.

Sublingual immunotherapy. EBSCO DynaMed Plus website. Available at: . Updated April 6, 2017. Accessed June 13, 2017.

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