An Overview of Immunotherapy

Immunotherapy is the medical term your healthcare professional uses for what you may refer to as "allergy shots." If your immune system overreacts to allergens (allergic triggers), such as pollen, pet dander, or dust mites, you may benefit from immunotherapy. These allergens can trigger many different symptoms, and they can worsen asthma.

Doctor giving man allergy shot

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When you are exposed to one of your allergic triggers, your body produces a substance called immunoglobulin E (IgE). Symptoms develop when IgE then causes other cells to release substances that lead to allergic reactions or an asthma reaction.

Immunotherapy treatment may prevent you from having these allergic reactions.

Over time, you might experience less:

Immunotherapy exposes you to small amounts of your triggering allergen over time (either as an oral pill or an injection), inducing a process called desensitization. In addition to the treatment of asthma, immunotherapy can also be used to treat allergies, atopic dermatitis, and hay fever.

How Immunotherapy Works

With injection immunotherapy, you get scheduled injections to help you become tolerant of the allergens that cause your symptoms. Sublingual (under the tongue) tablet immunotherapy (SLIT) has been available in Europe and Canada for a number of years and became available in the United States in 2014. Treatment with any type of immunotherapy is only indicated if you have known reactivity or sensitivity to the components of the therapy.

For example, one treatment called the 5 grass sublingual tablet contains the grasses Timothy, Orchard, Perennial Rye, Kentucky Blue Grass, and Sweet Vernal. Other sublingual treatments are directed towards ragweed and dust mites. These immunotherapy treatments will only be effective if you are allergic to the components of the treatment.

Slowly, your body becomes less sensitive to the allergen, which may result in decreased symptoms or total resolution to the symptoms that normally occur when you are exposed to the particular allergen.

Who Benefits From Immunotherapy?

Immunotherapy works best for patients with allergic rhinitis, allergic conjunctivitis, or allergic asthma. Immunotherapy can also be used in the treatment of atopic dermatitis or to prevent allergies from insect stings.

Before embarking on immunotherapy as a treatment, you need to consider the following:

  • Length of allergy season: If your allergies last for a really short time, immunotherapy may not be worth it. Generally, immunotherapy is considered for patients who have symptoms for a significant part of the year.
  • Other avoidance techniques: Are there other measures (e.g. removing a pet from the bedroom) that might be effective? Immunotherapy is like any other medication—there can be significant side effects. Make sure you have done everything you can to identify and avoid your asthma triggers before committing to immunotherapy.
  • Time: Immunotherapy is a significant time commitment and will involve frequent trips to your healthcare provider.
  • Cost: Immunotherapy is expensive and you will need to check with your insurance to ensure you are covered.

How Effective Is Immunotherapy?

Studies have demonstrated improvement in asthma symptoms and bronchial hyperresponsiveness with immunotherapy when the reaction is associated with allergies to grass, cats, house dust mites, and ragweed. However, asthma patients usually have allergies to more than one substance, and few studies have evaluated the effectiveness of immunotherapy for multiple allergens. The multiple allergen mixes, however, are the most common immunotherapy used by healthcare providers in practice.

It is also not clear if immunotherapy is better than treatment with inhaled steroids. It can take up to six months to a year before you notice any improvement in your asthma symptoms after starting immunotherapy.

Side Effects of Immunotherapy

Because immunotherapy exposes you to allergens that cause you to have asthma symptoms, there is a chance that you might have an asthma attack after the immunotherapy injection.

In-Office Treatment

Your healthcare provider will likely require you to stay in the office for a period of time after your immunotherapy injection to make sure your breathing is okay.

If you already have severe asthma, you are more likely to experience a severe allergic reaction called anaphylaxis. If you experience a sensation of your throat closing, hives on the skin, nausea, or dizziness, these could be symptoms of anaphylaxis. Most of these severe symptoms occur within 30 minutes of receiving an injection.

You may experience a local reaction at the site of the injection that can be managed with ice and over-the-counter pain medications.

SLIT Therapy

With SLIT therapy, you will be self-administering at home.

  • Severe allergic reactions are a possibility and your healthcare provider will discuss treatment at home and may prescribe an epinephrine auto-injector, in case you experience this side effect.
  • Local minor reactions may also occur and include itching or burning of the mouth or lips where the medicine is placed. The local reactions usually stop after a few days and tend to decrease over time.
  • Gastrointestinal symptoms, like diarrhea, can occur as well.

How Long Will I Need Immunotherapy?

Immunotherapy treatments will usually continue for three to five years. Children and adults can benefit, but this treatment is not commonly given to preschool-aged children. One reason is that some of the side effects can be difficult for children in this age group to express. Also, there needs to be a clear relationship between a trigger (i.e. pollen, animal dander, or dust mites) and a reaction.

The optimal duration of SLIT therapy has not been determined, but one small study of patients treated with SLIT due to dust mites looked at patients treated for three, four, and five years. Decreases in symptoms were noted seven, eight, and nine years, respectively. Current evidence seems to indicate the treatment effect is similar to that seen with injections.

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By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.