by EBSCO Medical Review Board


Allergen immunotherapy uses tiny doses of an allergen to lower the body’s reaction to it. There are two types:

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

Reasons for Procedure

Allergen immunotherapy is done to lower or stop the body's reaction to an allergen. It may reduce or end the need for allergy medicine. It works best for:

  • Severe hay fever
  • Life-threatening reaction to insect stings
  • Dust mite allergy
  • Animal allergy
Insect Bites
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Possible Complications

Problems are rare, but all procedures have some risk. Your doctor will review problems that may happen, such as:

  • Skin redness, swelling, and itching
  • Sneezing
  • Nasal congestion
  • Hives
  • Lightheadedness
  • Infection at an injection site (for SCIT)

Rare problems may be:

  • Throat swelling
  • Wheezing or tightness in the chest
  • Nausea

Talk to your doctor about ways to manage things that may raise your risk, such as:

What to Expect

Prior to Procedure

Tests will be done to learn which allergens are causing problems. These may be skin prick tests or blood tests. This information will help choose which allergens and doses to use.

Talk to your doctor about all medicines and supplements you are taking. Some may need to be stopped up to 1 week before surgery.


Anesthesia is not needed.

Description of the Procedure

The allergen will be given in one of two 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 of the allergen are placed under your tongue for 1 to 2 minutes.

You will be given a schedule. It will start with a build-up phase where the amount of allergen is slowly increased. The maintenance phase is when the dose will stay the same, but there may be fewer treatments.

Treatment will need to be repeated over 3 to 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
  • Watch you for an allergic reaction

At Home

It will take time before the body's reaction to the allergen changes.

Call Your Doctor

Call your doctor if you have:

  • Signs of infection, such as fever and chills
  • Redness, swelling, pain, bleeding, or discharge from an injection site
  • Skin redness, swelling, and itching
  • Hives
  • Problems breathing
  • Nausea
  • Lightheadedness

If you think 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 (immunotherapy). American Academy of Allergy, Asthma, and Immunology website. Available at: Accessed November 19, 2019.

Allergy shots. Kids Health—Nemours Foundation website. Available at: Updated April 2014. Accessed November 19, 2019.

Allergy shots (subcutaneous immunotherapy). American College of Allergy, Asthma, and Immunology website. Available at: Updated December 28, 2017. Accessed November 19, 2019.

Roberts G, Pfaar O, et al. EAACI Guidelines on Allergen Immunotherapy: Allergic rhinoconjunctivitis. Allergy. 2018 Apr;73(4):765-798.

Subcutaneous immunotherapy for aeroallergens. EBSCO DynaMed website. Available at: . Updated June 21, 2018. Accessed November 19, 2019.

Sublingual immunotherapy. EBSCO DynaMed website. Available at: . Updated May 31, 2019. Accessed November 19, 2019.

Revision Information

  • Reviewer: EBSCO Medical Review Board James P. Cornell, MD
  • Review Date: 09/2019
  • Update Date: 09/11/2020