An Overview of Immunotherapy

Immunotherapy is the medical term your healthcare provider uses for what you may refer to as "allergy shots." When your immune system overreacts to allergens, such as pollen, pet dander, and dust mites, you may benefit from immunotherapy.

Doctor giving man allergy shot

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When you are exposed to one of these triggers, your body produces a substance called immunoglobulin E, or IgE. IgE then causes other cells to release other substances that lead to asthma symptoms as part of the pathophysiology of asthma.

By making your body less sensitive to your allergic asthma trigger, you may be able to decrease some of your chronic symptoms, such as:

Immunotherapy exposes you to small amounts of your triggering allergen over time (either as an oral pill or an injection) in 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

In some ways, immunotherapy is like a vaccine—you get an injection that gives you protection from asthma. With immunotherapy, your healthcare provider injects tiny amounts of an allergen subcutaneously or under your skin. This is usually done once or twice per week, and the amount of allergen is gradually increased.

Slowly, your body becomes less sensitive to the allergen, which may result in decreased or total resolution to the asthma symptoms that normally occur when you are exposed to the particular allergen. In short, allergy shots help you become tolerant of the allergens that cause your asthma symptoms. And immunotherapy can even stop or significantly lessen the allergic reactions you experience to certain triggers, such as pollen, dander, and dust mites.

Sublingual (under the tongue) tablet immunotherapy, or SLIT, has been available in Europe and Canada for a number of years and became available in the United States in 2014. Treatment 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 Timothy grass and ragweed. These immunotherapy treatments will only be effective if you are allergic or sensitive to the components of the treatment.

Who Benefits From Immunotherapy?

In general, immunotherapy works best for patients with allergic asthma. If you have difficult to control symptoms, medications do not work well for you, or you need multiple medications and still don't have great asthma control, you might consider immunotherapy. Additionally, immunotherapy is sometimes used in patients who do not want to take regular medication.

Patients with a clear relationship between their exposure to an allergen and development of symptoms will gain the most benefit. Immunotherapy can also be used in the treatment of allergic rhinitis or to prevent allergies from stinging insects.

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

  • Length of allergy season—If really short, 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 you making 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 there are allergies to grass, cats, house dust mites, and ragweed. However, few asthma patients have allergies only to 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 is exposing you to allergens which cause you to have asthma symptoms, there is a chance that your asthma might get worse and you might have an asthma attack after the immunotherapy injection. 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. Additionally, you may experience a local reaction at the site of the injection that can be managed with ice and over-the-counter pain medications.

With SLIT therapy, you will be self-administering at home over time. As a result, severe allergic reactions are a possibility and your healthcare provider will discuss treatment at home and likely prescribe an epinephrine auto injector, should this side effect occur. Local minor reactions may also occur and include itching or burning of the mouth or lips where the medicine is placed. Gastrointestinal symptoms, like diarrhea, occur as well. The local reactions usually stop after a few days or a weekend and tend to decrease over time.

How Long Will I Need Immunotherapy?

Immunotherapy will usually last for three to five years. While both children and adults benefit, this treatment is not commonly undertaken in preschool aged children. One reason is that some of the side effects can be difficult for children in this age group to vocalize. 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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