This article is part of our Allergy Treatment resource center, covering all aspects of allergy treatment diagnosis, treatment, and management.
What Sublingual Immunotherapy Is
Sublingual immunotherapy (SLIT) is a form of allergen immunotherapy in which allergen extracts are administered under the tongue rather than by injection. The goal is the same as subcutaneous immunotherapy (allergy shots): to gradually reduce allergic sensitivity to specific environmental allergens through repeated allergen exposure. SLIT tablets dissolve rapidly under the tongue, delivering allergen to immune cells in the oral mucosa. This page is part of the allergy treatment section and addresses sublingual tablets specifically; it should not be confused with oral immunotherapy for food allergy, which is a different treatment with different indications, mechanisms, and outcomes.
Tablets Versus Compounded Liquid Drops
Two forms of sublingual immunotherapy are used in clinical practice: FDA-approved standardized allergen tablets and compounded sublingual liquid drops (also called SLIT drops). These are fundamentally different in regulatory status. FDA-approved tablets have been evaluated through clinical trials and regulatory review for specific indications and allergens. Compounded sublingual drops are prepared individually by pharmacies from bulk allergen extracts; they are not FDA-approved, have not been evaluated through the same regulatory process, and are not covered by most insurance plans. Patients considering sublingual immunotherapy should ask their clinician explicitly whether they are being prescribed an FDA-approved product or compounded drops, and understand the distinction.
FDA-Approved Sublingual Allergen Tablets
The FDA-approved sublingual tablets available in the United States target specific environmental allergens: Grastek is approved for Timothy grass pollen allergy; Oralair is approved for a five-grass pollen mixture; Ragwitek is approved for short ragweed pollen allergy; and Odactra is approved for house dust mite allergy. Each product has specific indications, age approvals, and contraindications detailed in its prescribing information. Not every environmental allergen has an FDA-approved sublingual tablet option; available products are limited to these four as of this writing. Sublingual tablets are not a treatment for food allergy in the same clinical sense as oral immunotherapy (OIT).
First-Dose Observation and At-Home Dosing
The first dose of a sublingual allergen tablet must be administered in a medical setting with the ability to observe for and treat allergic reactions. Subsequent doses are taken daily at home — this convenience is a significant practical difference from allergy shots, which require clinic visits throughout treatment. Patients should understand that local reactions (oral itching, tingling, swelling) are expected and usually manageable, while systemic reactions are uncommon but possible, particularly with early doses. Prescribed epinephrine should be available for patients at risk.
Expected Timeline and Adherence
Symptom benefit from sublingual tablets typically develops over months and may increase with continued treatment across multiple seasons. Clinical trials generally show measurable benefits within the first year, with continued improvement in subsequent years. Adherence to daily dosing is essential — the treatment requires consistent use to be effective. Stopping treatment early or taking doses inconsistently reduces the likelihood of benefit and may require restarting the treatment course. Discuss the recommended duration for the specific product you are prescribed with your allergist.
Comparison With Allergy Shots
Allergy shots (subcutaneous immunotherapy) require more frequent clinic visits — typically weekly during buildup and monthly during maintenance — but offer access to a broader range of allergens and combinations than currently available sublingual tablets. Both approaches have been shown to be effective for the allergens they address. The choice between them depends on factors including which allergens are involved, patient preference for clinic visits versus daily home dosing, insurance coverage, and the availability of FDA-approved tablet products for the specific allergen. An allergist can assess which approach, if either, is appropriate for an individual patient's profile.
- FDA — Sublingual Immunotherapy Allergy Tablets (not externally verified)
- AAAAI — Allergy Testing and Treatment (not externally verified)
- ACAAI — Allergy Treatment (not externally verified)