Patient education: Sublingual immunotherapy (Beyond the Basics)

INTRODUCTION — Sublingual (ie, under the tongue) immunotherapy (abbreviated SLIT) is a method of treating allergic nasal and eye symptoms, as well as mild-to-moderate allergic asthma, in patients who are allergic to certain pollens or dust mites. The most effective form of SLIT uses quickly dissolving tablets that are taken daily, and this is the only form of SLIT that is approved by the US Food and Drug Administration (FDA).

FREQUENTLY ASKED QUESTIONS

Who can be treated with SLIT? — To be eligible for SLIT, you must have allergies to certain pollens and/or dust mites, as shown either by skin testing or blood test. In addition, you must be able to remember to give yourself the treatment every day as prescribed because it won't work well if you don't take it consistently.

What are the other ways to treat my allergies? — The other ways to treat allergies are avoidance, medications, injection immunotherapy, and immunotherapy using a sublingual liquid (drops).

Allergen avoidance — Reducing your exposure to the things that you are allergic to is always the first step in treatment, and your allergist can give you specific advice about the allergens that are important for you. Unfortunately, it's hard to avoid pollens and dust mites well enough to control symptoms. You can find a new home for pets that are causing allergies, but not everyone is willing to do so, and, even if you don't have a pet, simply being around people who do can cause symptoms.

Medications — You can use various medications to manage nasal or eye allergies and allergic asthma. These include antihistamines, decongestants, nasal sprays, eye drops, and asthma inhalers. These medications may provide symptomatic relief for as long as you take them, but they do not change your underlying allergies.

Allergen immunotherapy has the potential to provide long-lasting clinical remission of symptoms, whereas antihistamines and decongestants only provide symptomatic relief, and even maintenance controller medications for asthma, such as inhaled corticosteroids, lose their effect within a few weeks once discontinued, thus offering no long-lasting protection.

Other types of immunotherapy — Subcutaneous immunotherapy (SCIT) is a long-established, traditional form of allergen immunotherapy. In SCIT, a mixture of the allergens to which you are allergic is prepared, and injections of the extract are gradually increased (over 16 to 20 weeks) as tolerated to a maintenance regimen that is then administered at your physician's office every two to four weeks over three to five years. In contrast to SLIT-tablets, another form of allergen immunotherapy is that of sublingual drops (SLIT-drops). This method involves putting drops of a solution containing a mixture of allergens under the tongue. This approach is used in various parts of the world. However, it is not US Food and Drug Administration (FDA) approved in the United States, although it can be given "off label" (meaning that a physician can prescribe it for a condition for which it has not been officially approved). Most studies have shown that it is less effective than injection immunotherapy or SLIT.

What is the goal of immunotherapy? — Allergen immunotherapy (of any type) changes how your immune system reacts to the allergen in question, essentially teaching your immune system to ignore it. Many people are able to achieve long-lasting control of their symptoms with a course of treatment (usually four to five years). In addition, allergen immunotherapy initiated for nasal or eye allergies may prevent the development of allergic asthma, as well as prevent the onset of new allergies to other airborne allergens.

How does SLIT compare with traditional allergy shots? — SLIT has advantages and disadvantages compared with injection immunotherapy.

The advantages are:

●Safety – There is a low to negligible risk of serious, "whole body" allergic reactions (ie, anaphylaxis [drop in blood pressure, feeling like you might pass out, difficulty breathing, swelling of the throat, hives]).

●Convenience – SLIT can be self-administered at home.

●Comfort – It may be an appealing option for people who do not like getting injections.

The disadvantages are:

●SLIT-tablets are only available for a limited number of allergens.

●SLIT-tablets appears to be slightly less effective than injection immunotherapy.

How is SLIT given? — Each day, you put the tablet under your tongue and let it dissolve completely. Your fingers and hand must be absolutely dry before touching the tablet, or you can lose some of the dose on your fingers. Do not swallow for at least one minute, and do not eat or drink anything for a minimum of five minutes. After that, there are no restrictions on eating or activity. The first dose of SLIT is given in the allergy office under observation. You give yourself the tablet and stay for 30 minutes of observation by the medical staff. You should also use this visit to ask any questions and make sure you understand exactly what to do at home.

What are the side effects of SLIT? — The most common side effects are itching and mild swelling of the inside of the mouth, area under the tongue, lips, and throat, which can last up to 60 minutes. As many as one-quarter of people experience this. These side effects are usually most noticeable with the first few doses and subside with time (persisting for less time with each day's treatment and typically resolving completely within the first one to two weeks).

About 10 to 14 days after starting treatment, some people may feel some swelling deeper in the throat, but this typically also passes with time (again, lessening each day and resolving within a few weeks). Very rarely, the swelling is severe enough to require treatment with an injection of epinephrine. Therefore, if you start to experience this type of adverse side effect, you should contact the office to discuss further actions.

Whole body allergic reactions are extremely rare with SLIT, and these are also treated with an injection of epinephrine. Because you are taking the treatment at home, you are required to have an epinephrine autoinjector. You should use it and call 911 if you have a serious allergic reaction that affects your ability to breath or makes you feel that you might pass out.

Another uncommon side effect of SLIT is the development of inflammation in the esophagus (tube that carries food from the mouth to the stomach), called eosinophilic esophagitis. This may feel like pain in the mid-chest that doesn't get better with medicines for acid reflux or pain or difficulty with swallowing. Tell your allergist if you have any of these symptoms while taking SLIT. This may require stopping the treatment. If SLIT is stopped, this condition does resolve.

How long does it take to start working? — SLIT takes three to four months to start working, but additional improvement can occur with continued long-term use. The tablets must be taken daily to be effective.

What time of year should I take SLIT for pollen allergies? — You should start taking the tablets four months before the beginning of the pollen season:

●For grass pollen allergies, start the tablets in January.

●For ragweed pollen allergies, start the tablets in May.

Take the tablets daily through the pollen season. Most people stop at the end of the pollen season and start again the next year. However, some patients with grass allergies may prefer to take the tablet year-round to treat their grass allergies, especially if you live in a place where grass is growing year-round.

Dust mite immunotherapy can be started any time of year and is taken year-round.

Are there situations in which I should stop taking the tablets? — Yes. Stop taking the tablets if you have major dental work that involves cutting the gums or pulling a tooth, any other injury to the mouth, or inflammation in the mouth (ulcers, thrush, or other oral disorders). This is necessary because the allergen can enter the blood stream too quickly if the lining of the mouth has cuts or openings in it. Restart treatment once the mouth is healed.

Can I take more than one type of tablet? — Yes, if you are allergic to both grasses (a spring-summer allergen for most people) and ragweed (a fall allergen), it is possible to receive SLIT for both allergens. In this case, the treatments are given sequentially: First, the grass tablet and then, after two weeks, the ragweed tablet is started. Some allergists prefer to give one tablet in the morning and one in the evening, but two tablets can also be given five minutes apart.

If you are allergic to dust mites, which cause year-round symptoms, that is usually started first, and then, a few days later, treatment with the appropriate pollen tablet can be started.

Other medications should be taken normally as SLIT-tablets do not interact with them.

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Environmental allergies in adults (The Basics)
Patient education: Environmental allergies in children (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Allergic rhinitis (Beyond the Basics)
Patient education: Allergic conjunctivitis (Beyond the Basics)
Patient education: Trigger avoidance in allergic rhinitis (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Sublingual immunotherapy for allergic rhinitis and conjunctivitis: SLIT-tablets

Websites — The following organizations also provide reliable health information:

●United States National Library of Medicine

(https://medlineplus.gov/healthtopics.html)

●American College of Allergy, Asthma & Immunology

(https://acaai.org/allergies/management-treatment/allergy-immunotherapy/slit/)

●American Academy of Allergy, Asthma & Immunology

(https://www.aaaai.org/tools-for-the-public/drug-guide/sublingual-immunotherapy-(slit)-allergy-tablets)