Sublingual Immunotherapy (SLIT): Allergy Tablets & Drops

Written by Empire Medical Training Editorial Team

Medically reviewed by Sherry Wehner, MD Board-Certified Pathologist & Dermatopathologist; Aesthetic & Wellness Medicine

Updated June 2026 ·10 min read

Sublingual immunotherapy (SLIT) is one of two main forms of allergen immunotherapy — the only category of allergy treatment that actually changes the underlying immune response rather than just suppressing symptoms. Instead of an injection, the allergen is placed under the tongue, where it is absorbed and, over months of repeated dosing, trains the immune system toward tolerance. For patients, the appeal is obvious: much of the treatment happens at home, without weekly trips to the office.

This guide situates SLIT within the broader field of allergy immunotherapy and is written for clinicians who want an accurate, candid overview. It is clinical education, not medical advice, and nothing here should be read as a treatment protocol, dosing schedule, or substitute for current FDA labeling. As Dr. Sherry Wehner frames it in Empire's course, immunotherapy is the most rewarding part of allergy care — but only when it is offered to the right patient, with the right product, and with emergency readiness on hand.

What is sublingual immunotherapy?

The principle behind all immunotherapy is the same as the older idea of “desensitization.” A patient who is allergic to an environmental allergen — a grass, a tree pollen such as mountain cedar, ragweed, or house dust mite — is given that same allergen in small, controlled, gradually increasing amounts. Over time, the immune system shifts away from the IgE-driven mast-cell response that produces the familiar itching, redness, and swelling, and toward tolerance. As Dr. Wehner puts it, immunotherapy is not a cure, but it can dramatically decrease symptoms and improve quality of life: take someone who has suffered for years with debilitating seasonal allergies, give them a year or two of treatment, and they can lead a relatively normal life.

SLIT delivers that allergen sublingually — the drops or a dissolvable tablet are held under the tongue, then swallowed or spit out per the product instructions. The oral mucosa is rich in tolerance-promoting immune cells, which is why this route can drive desensitization without an injection. Because the patient can administer the dose themselves, SLIT is, in Dr. Wehner's words, “much more convenient for the patient because they can take the drops home and administer the drops to themselves.” That convenience is SLIT's central advantage — and the honest counterweight is that it is generally less effective than the injectable route and, for compounded drops, not covered by insurance.

SLIT vs SCIT (allergy shots): a comparison

The two delivery routes for immunotherapy are SCIT (subcutaneous immunotherapy, the conventional “allergy shots”) and SLIT (sublingual immunotherapy). They share the same biological goal but differ meaningfully in convenience, safety, evidence, and cost. The table below summarizes the practical trade-offs.

The honest summary Dr. Wehner gives is direct: SLIT is more convenient, but “much less effective and also not covered by insurance,” and she does not use compounded drops in her own practice. That is one experienced clinician's stance, not a verdict against SLIT — the FDA-approved tablets sit on firmer ground than the compounded drops, and the right choice depends on the patient, the allergen, and what the patient will realistically adhere to.

FDA-approved tablets vs off-label drops

This is the single most important distinction on this page, and getting it wrong is a real compliance and patient-safety problem. SLIT is not one product — it is two very different regulatory situations.

FDA-approved SLIT tablets exist for a defined set of allergens: grass pollen, ragweed, and house dust mite. These dissolvable tablets went through the standard regulatory pathway, with their own labeling for indications, dosing, and the supervised first dose. When you use an approved tablet for its approved allergen, you are working with a vetted product.

Compounded sublingual allergy drops are a different matter. They are typically prepared from allergen extracts and used off-label for SLIT — they are not FDA-approved for that purpose. That does not make them illegitimate, but it does mean a provider must understand and disclose that they are off-label, that they are generally not insurance-covered, and that the evidence base is weaker than for the approved tablets. Do not present allergy drops to patients as if they carried the same FDA standing as the tablets. The intellectually honest framing — the one that protects both the patient and the practice — is to be explicit about which category you are offering and why.

Who is a candidate for SLIT?

Like all immunotherapy, SLIT is for environmental allergens — pollens, dust mite, animal dander, mold — confirmed by appropriate testing. Immunotherapy is not recommended for food allergies or contact allergies; for those, the standard of care is avoidance. Candidate selection begins with documenting genuine IgE-mediated environmental allergy, usually through skin-prick testing or specific-IgE blood testing, correlated with the patient's history. Immunotherapy of any kind is a commitment that runs roughly a year or more, so a frank conversation about adherence belongs at the front of the process.

SLIT is a particularly reasonable consideration for patients who are good immunotherapy candidates but cannot or will not commit to the in-office injection schedule — the patient whose work or distance makes weekly visits impractical, the needle-averse patient, or one whose dominant allergen is well matched to an approved tablet. The flip side is honesty about its ceiling: for a patient with multiple strong sensitivities who wants the most effective, insurance-covered, disease-modifying option, SCIT is generally the stronger tool. Patients with a history of anaphylaxis, uncontrolled asthma, or systemic reactions are more complex and, in Dr. Wehner's practice, are referred to a board-certified allergist/immunologist rather than managed with routine immunotherapy — a threshold worth respecting regardless of route.

The time course and what to expect

Immunotherapy is a marathon, and setting that expectation up front is part of doing it well. Conventional treatment has a build-up phase followed by a maintenance phase, and the full course typically runs about a year or longer before retesting to see how the patient's allergies have improved. SLIT compresses the logistics — most dosing happens at home — but the underlying biology still takes time. Tolerance builds gradually over months; there is no overnight result.

Two practical points carry over from the injectable world. First, consistency matters more than perfection: doses should not simply be skipped, because gaps stretch out the timeline. Second, patients should understand that immunotherapy is a treatment, not a cure — the goal is a meaningful reduction in symptoms and a better quality of life, sustained while on therapy and, ideally, durable afterward. The specific build-up and maintenance dosing schedules, the escalation logic, and how to handle missed or reaction-triggering doses are taught in clinical detail in Empire's Allergy Test & Treatment Training rather than reproduced here.

First-dose observation and the anaphylaxis risk

SLIT's safety profile is genuinely favorable — most reactions are local, such as itching or mild swelling in the mouth, throat, or under the tongue, and they tend to settle as treatment continues. That favorable profile is exactly why SLIT can be taken at home. But “favorable” is not “zero,” and the responsible framing is that the anaphylaxis risk is lower than with SCIT but still real.

This is why the FDA-approved tablets are structured around a supervised first dose in the office with a period of observation for any systemic reaction before the patient continues at home. It mirrors the discipline Dr. Wehner applies to injectable immunotherapy: emergency preparedness is never optional. In her clinic, immunotherapy patients are prescribed their own epinephrine auto-injectors and must bring them to be treated; the staff is trained to use them (“blue to the sky, orange to the thigh”). The same principle extends to at-home SLIT — the patient should have epinephrine available, know the warning signs of a serious reaction, and have clear instructions on when to use it and seek emergency care. Anaphylaxis is a medical emergency whose first-line treatment is intramuscular epinephrine. Any clinician offering immunotherapy in any form must be ready for it.

For context, allergic disease is extraordinarily common — allergies affect more than 56 million Americans, roughly 30% of adults have environmental allergies, and allergy is the sixth leading cause of chronic disease in the United States. There are fewer than 6,000 board-certified allergists to serve them, which is precisely the access gap that makes immunotherapy a meaningful service for trained primary-care and aesthetics practices to offer responsibly — while still referring the genuinely high-risk patient onward.

Offering SLIT in your practice

For a practice already doing allergy testing, SLIT can extend the immunotherapy conversation to patients who would otherwise decline shots. The operational reality is that immunoserum preparation and the matching of allergens to a patient's results are not trivial — cross-reactivity, mixing constraints, and stepped dosing all come into play. Dr. Wehner's strong recommendation, at least when starting out, is to work with a certified allergy lab rather than mixing your own — the same way one uses a compounding pharmacist rather than compounding in-house. A full-service lab supplies the materials, advises on the correct allergens for your region, and supports billing and coding.

On reimbursement, the candid picture is that compounded sublingual drops are generally an out-of-pocket service, whereas conventional injectable immunotherapy is typically covered when a patient has three or more positive environmental allergens on skin testing. FDA-approved tablets fall between, depending on payer and indication. Coding for allergy testing and immunotherapy follows defined CPT and ICD-10 conventions, and getting it right is where a great deal of revenue is won or lost — the average practice loses 10–30% of potential revenue to incorrect coding. The specific coding workflow and the build-out of an in-office allergy program are covered in depth in the course rather than here. The throughline is simple: offer SLIT honestly, document carefully, keep emergency readiness in place, and refer the complex patient.