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Immunotherapy for Allergies

Reviewed by: HU Medical Review Board | Last reviewed: September 2022

Immunotherapy is one of several treatments for allergies. It is used along with allergy medicine and lifestyle changes. It is used to treat severe allergy symptoms and when allergy medicines or avoidance are not working.1-9

How does immunotherapy work?

Immunotherapy helps prevent symptoms from starting because it makes the body less sensitive to an allergen. This process is called desensitization. With immunotherapy, an allergen is slowly introduced to the body at increasing concentrations. Over time, this trains the immune system to better tolerate that allergen. This causes symptoms to decrease and sometimes disappear.1-9

Immunotherapy works best for environmental allergies like those to pollens, dust mites, insect stings, and cats. It seems to work less well for mold and dog allergies. It has been used for peanut allergies and is being studied for other food allergies.2,6,10

Immunotherapy can also be helpful when allergies are a trigger for asthma.4

Immunotherapy was first introduced more than 100 years ago. Research continues on the effectiveness and safety of immunotherapy treatment options.5

Types of immunotherapy

There are different types of immunotherapy for allergies, including:1-10

  • Subcutaneous immunotherapy (SCIT)
  • Sublingual immunotherapy (SLIT)
  • Epicutaneous immunotherapy (EPIT)
  • Oral immunotherapy (OIT)

Each type of immunotherapy is used for specific types of allergies.

Subcutaneous immunotherapy (SCIT)

SCIT is also known as “allergy shots.” It is the most common form of immunotherapy. Tiny amounts of allergens are injected under the skin. The doses are small at first and increase slowly over time. This process is called desensitization.1,4,6

Shots are generally given once or twice a week for 6 to 8 months. As immunity increases, shots are given weeks apart. Once a maintenance dose is reached, shots can be given every few weeks.1

This maintenance phase may last for 3 to 5 years. Eventually, it leads to a decrease in symptoms. Sometimes a person’s allergic reaction disappears for years.1,5

SCIT is most effective in treating:5

  • Allergic asthma
  • Hay fever (allergic rhinitis)
  • Pink eye (conjunctivitis)
  • Insect sting allergies

Sublingual immunotherapy (SLIT)

SLIT is similar to SCIT. However, with this form of immunotherapy, tablets or liquid that contains the allergen is placed under the tongue daily. For seasonal allergies, treatment begins months before the season. Symptom benefit has been seen in treatment up to 3 years.6-9

The use of sublingual immunotherapy is growing. It was first approved in 2014 for use in the United States. It is approved for grass, ragweed, and dust mite allergies.6,8

SLIT may be more convenient than going to the doctor for weekly shots, but it may not be as effective for as many allergens as SCIT. SLIT is safer in regards to less systemic reactions. SLIT is more often used in Europe.1,5,8

The first dose of SLIT is given in a doctor’s office so you can be monitored for serious reactions. Treatment then continues at home. People using SLIT are also often prescribed an epinephrine autoinjector in case of serious reactions that happen outside the doctor’s office.6-8

Oral immunotherapy (OIT)

OIT is a popular focus of food allergy research. It is not yet a standard therapy. The hope is to create a treatment that helps people who have serious reactions to food. This would protect people from life-threatening reactions if they accidentally eat or breathe in a food that is dangerous to them.10

In the United States, there is 1 oral immunotherapy approved to treat peanut allergy. Other oral immunotherapy for food allergies is delivered through clinical trials.10

Epicutaneous immunotherapy (EPIT)

EPIT is delivered through the skin. It is another way to desensitize someone to a food allergen. EPIT is an adhesive patch applied daily to develop and maintain desensitization to a food protein. The patch has a fixed dose.5,6

What are the possible side effects of immunotherapy?

Side effects can vary depending on what you are allergic to and the type of immunotherapy you receive.

There are some risks with immunotherapy. This is because something you are allergic to is being put directly into the body. Reactions range from a mild rash at the injection site to anaphylaxis. Mouth tingling or itchiness may occur with immunotherapy given by mouth. This is why immunotherapy is started at a doctor’s office and epinephrine auto-injectors are prescribed. This allows your doctor to monitor you for signs of a serious reaction.2,5

Most people taking immunotherapy are told to carry epinephrine with them at all times. Most are required to wait in the medical office for at least 30 minutes after getting their shots. Immunotherapy may not be right for people with uncontrolled asthma.2

These are not all the possible side effects of immunotherapy. Talk to your doctor about what to expect during treatment. You also should call your doctor right away if you notice any changes that concern you.

Things to know about immunotherapy

Immunotherapy requires a major time commitment. Doctor visits last for 3 to 5 years. Such a long-lasting treatment can be costly, even with insurance.1,5,6-9

Before beginning immunotherapy, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

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