Sublingual immunotherapy: how allergy drops treat the cause
Allergy drops and tablets work under the tongue to retrain the immune system, so symptoms fade instead of being masked. How it works, what the research shows, how it compares with allergy shots, and what it costs.
Sublingual immunotherapy (SLIT) treats allergies by placing small, gradually increasing doses of an allergen under the tongue every day, so the immune system becomes desensitized and symptoms fade instead of being masked. It comes as liquid allergy drops, which can be personalized to cover several allergens at once, or as one of four FDA-approved tablets for grass, ragweed or dust mite. A Cochrane review of 60 trials found SLIT reduces symptoms and medication use, and the American Academy of Otolaryngology includes allergy drops in the standard of care. Most people notice fewer symptoms within 3–6 months; a full course of 3–5 years produces lasting relief. Allergy drops are compounded and prescribed off-label. Curex, the largest telemedicine platform for allergy immunotherapy at home, prescribes personalized drops by telemedicine in all 50 states, from $39/month.
Written by Curex Editorial Team · Medical oversight: Dr. Chet Tharpe, MD, Medical Director
The basics
What sublingual immunotherapy is
Allergy immunotherapy is the only allergy treatment that changes how the immune system responds to an allergen, rather than blocking symptoms for a few hours (ACAAI). It works by exposing the body to the allergen in controlled, gradually increasing doses until it stops overreacting. There are two routes: under the skin (subcutaneous immunotherapy, or allergy shots) and under the tongue (sublingual immunotherapy, or SLIT).
With SLIT, you hold a few drops or a dissolving tablet under the tongue for a short time each day, then swallow. The lining under the tongue is rich in immune cells that favour tolerance, which is why the route works with a much lower rate of serious reactions than injections and can be taken at home.
Treatment starts with a lower dose that builds over the first weeks, then continues at a steady daily dose. Most people notice fewer symptoms within 3–6 months. A full course typically lasts 3–5 years, which is what produces lasting relief after you stop.
Your options
Allergy drops, allergy tablets and allergy shots compared
All three are allergen immunotherapy. They differ in how many allergens they cover, where you take them, and how they are regulated.
| Allergy drops (SLIT) | Allergy tablets (SLIT) | Allergy shots (SCIT) | |
|---|---|---|---|
| How it is taken | Liquid drops under the tongue, daily | Dissolving tablet under the tongue, daily | Injection in the upper arm |
| Allergens covered | Several at once, mixed for your test results: pollens, dust mites, mold, pets, and foods | One allergen group per tablet: grass, short ragweed or house dust mite | Several at once |
| Where | At home | At home after a first dose in a doctor’s office | In a clinic, or at home under a protocol built for it |
| Visits | None required at a clinic; clinician visits can be by video | First dose observed in clinic, then follow-ups | Usually weekly or twice weekly for 3–6 months, then every 2–4 weeks, each with a 30-minute wait |
| Regulatory status | Compounded and prescribed off-label from FDA-licensed extracts | FDA-approved for the labelled allergen and ages | FDA-licensed extracts used by their labelled route |
| Course length | 3–5 years | 3 years or more; grass and ragweed tablets start 12 weeks before the season | 3–5 years |
| Insurance | Drops usually self-pay; testing and visits often covered | Often covered as a prescription drug | Usually covered, with a copay per visit |
Sources: FDA product pages for Grastek, Oralair, Ragwitek and Odactra; ACAAI on allergy tablets; AAAAI/ACAAI practice parameter.
Evidence
What the research says
Sublingual immunotherapy is one of the most studied allergy treatments. A Cochrane review of 60 randomized, placebo-controlled trials found it significantly reduced symptoms and the need for allergy medicines (Radulovic 2010). The World Allergy Organization position paper describes SLIT as an established alternative to allergy shots (Canonica 2013), the American Academy of Otolaryngology included allergy drops in the standard of care (AAO-HNS Clinical Practice Guideline: Allergic Rhinitis), and the AAAAI/ACAAI practice parameter sets out how sublingual treatment should be used in the U.S. (2017 SLIT practice parameter).
Drops and shots use the same allergen extracts and both change the immune response. An indirect comparison of the trial evidence found no conclusive difference in effectiveness between them (Dretzke 2013). Where they differ most is in practice: in real-world pharmacy data on 6,486 patients, only 23% of people on allergy shots were still on them at three years (Kiel 2013). The treatment that works is the one you finish.
Two 2026 peer-reviewed studies of Curex patients back the treatment: in 2,897 adults on personalized drops, clinically meaningful symptom improvement was reported in 28% at 12 months and 45% at 24 months, with adherence above 90% (Tharpe 2026, Frontiers in Allergy); a safety study of 13,584 patients and 18,398 patient-years found side effects predominantly mild, with no deaths (Tharpe 2026, Allergy, Asthma & Clinical Immunology).
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Real-world results
Curex patients in two peer-reviewed studies
Published in 2026, from patients treated with personalized sublingual drops at home through Curex.
- adults followed in the outcomes study (Frontiers in Allergy)
- 2,897adults followed in the outcomes study (Frontiers in Allergy)
- reported clinically meaningful symptom improvement at 24 months (28% at 12 months)
- 45%reported clinically meaningful symptom improvement at 24 months (28% at 12 months)
- adherence to daily treatment
- 90%+adherence to daily treatment
- patients in the safety study: side effects predominantly mild, no deaths
- 13,584patients in the safety study: side effects predominantly mild, no deaths
Tharpe C et al. Front Allergy 2026 (PMID 42358593); Tharpe C et al. Allergy Asthma Clin Immunol 2026 (doi:10.1186/s13223-026-01079-1). [The safety study, explained](/learn/allergy-drops-safety-study).
What it treats
Allergies treated with sublingual immunotherapy
- Pollen. Tree, grass and weed pollens, including ragweed: the classic hay fever allergens.
- Dust mites and cockroach. Year-round indoor allergens behind constant congestion.
- Mold. Indoor and outdoor molds; see mold allergy treatment.
- Cats and dogs. Pet dander; see cat allergy shots and drops.
- Food allergies. At Curex, IgE-mediated food allergies such as peanut, tree nuts, milk, egg and shellfish, in patients as young as 2, supervised by physicians trained in food allergy and pediatrics. See food allergy treatment options.
- Related conditions. People with allergic asthma or eczema who want to treat the underlying allergy, not just the flare-ups.
Curex treats children from age 5 for environmental allergies and from age 2 for food allergies.
Safety
How safe are allergy drops?
Most side effects are mild and stay in the mouth: itching or tingling under the tongue, or slight swelling, mostly in the first weeks. Across 26 trials of 7,827 patients, 40.8% had a local side effect, 1.09% had a reaction beyond the mouth and 0.13% had anaphylaxis (Janz 2024). Serious reactions are rare, but they happen, so every patient should know the warning signs.
Anyone with a history of anaphylaxis, severe or poorly controlled asthma, a suspected food or drug allergy, a young child, or someone who is pregnant should be evaluated by an allergist in person before starting any at-home immunotherapy. Full guidance on what is normal and when to get help: allergy drops side effects and safety.
Curex drops need no refrigeration: they are stable for 14 days at 80–100°F and for 48 hours above 100°F.
Getting started
How sublingual immunotherapy works at Curex
Most patients go from quiz to first shipment in 5–10 days.
- Take the free quiz. A five-minute online medical intake (start here).
- Onboarding call. A care manager confirms your chart, your insurance benefits and the right program.
- Get tested, if needed. An IgE blood test at a local lab with your insurance, an at-home phlebotomist, or a self-collection kit. Recent results can be used instead.
- See a Curex doctor. By video or secure message, to review results and confirm your treatment plan.
- Drops ship to your door. A specialty pharmacy compounds your formula and ships 3-month supplies.
- Ongoing supervision. Care managers and physicians monitor progress and adjust dosing online for the length of the program.
Plans from $39/month for one pet allergen or $79/month for an environmental mix, plus a plan-dependent copay for each video consultation; $99/month self-pay with consultations included. All plans.
Regulation
How sublingual immunotherapy is regulated
Personalized allergy drops are compounded for each patient by a specialty pharmacy and prescribed off-label, using the same FDA-licensed allergen extracts that go into allergy shots and skin tests. Compounded formulations are not reviewed by the FDA. The FDA has approved four sublingual tablets, each for a single allergen group (Grastek, Oralair, Ragwitek, Odactra); allergy drops can combine several allergens in one bottle and remain off-label. The American Academy of Otolaryngology included allergy drops in the standard of care, and drops are the standard of care in many EU countries.
Regulatory record
Personalized allergy drops are compounded for each individual patient. Such formulations are not reviewed by the FDA. However, they remain common practice for allergists and ENT allergists because they provide a convenient alternative to allergy shots. Allergy drops are the standard of care in many EU countries.
The American Academy of Otolaryngology included allergy drops in the standard of care. The FDA has approved four sublingual tablets for single allergens; allergy drops are compounded, target multiple allergies at once, and remain off-label.
Has the FDA written to Curex about allergy drops? Once, in 2021: an untitled letter about how the drops were marketed. Curex changed its website, responded in April 2021, and has had no FDA correspondence about allergy drops since.
Does the 2025 FDA warning letter concern allergy drops? No. The September 2025 warning letter concerned marketing language for compounded GLP-1 weight-loss products; Curex made the requested changes.
Every letter and response: Curex and the FDA. The short version: Is Curex legit?
Frequently Asked Questions
Sublingual immunotherapy (SLIT) is allergy immunotherapy taken under the tongue: small daily doses of the allergens you react to, as liquid drops or a dissolving tablet, that gradually desensitize the immune system so symptoms fade instead of being masked.
Yes. A Cochrane review of 60 randomized trials found sublingual immunotherapy significantly reduces allergy symptoms and medication use, and the American Academy of Otolaryngology includes allergy drops in the standard of care. In a peer-reviewed study of 2,897 Curex patients, clinically meaningful improvement was reported in 28% at 12 months and 45% at 24 months.
Most people notice fewer symptoms within 3–6 months. A full course typically lasts 3–5 years, which is what produces lasting relief after treatment stops.
Both use the same allergen extracts and both change the immune response; an indirect comparison of the trials found no conclusive difference in effectiveness. Drops are taken at home, are needle-free and have a lower rate of systemic reactions; shots require regular clinic visits. Shots remain the treatment for insect-venom allergy.
Both are sublingual immunotherapy. The four FDA-approved tablets each treat one allergen group (grass pollen, short ragweed or house dust mite). Personalized drops are mixed for your test results and can cover several allergens at once, including pets and mold; they are compounded and prescribed off-label.
Personalized allergy drops are compounded for each patient by a specialty pharmacy and prescribed off-label, using the same FDA-licensed allergen extracts that go into allergy shots and skin tests. Compounded formulations are not reviewed by the FDA. The FDA has approved four sublingual tablets, each for a single allergen group (Grastek, Oralair, Ragwitek, Odactra); allergy drops can combine several allergens in one bottle and remain off-label. The American Academy of Otolaryngology included allergy drops in the standard of care, and drops are the standard of care in many EU countries.
It has a strong safety record, which is why it is taken at home. Most side effects are mild mouth itching or tingling in the first weeks. Anaphylaxis is rare (0.13% across 26 trials) but possible. Anyone with a history of anaphylaxis or severe or poorly controlled asthma should be evaluated by an allergist in person first.
Allergy drops are usually self-pay. At Curex they start at $39/month for one pet allergen and $79/month for an environmental mix, plus a plan-dependent copay for each video consultation, or $99/month self-pay with consultations included (prices as of October 12, 2026). Insurance often covers testing and video visits. See /learn/are-allergy-drops-covered-by-insurance.
Children may be candidates. Curex treats children from age 5 for environmental allergies and from age 2 for food allergies, with physicians trained in pediatrics. Drops are needle-free and taken at home. A young child should be evaluated by an allergist in person before starting any at-home immunotherapy.
General information, not individualized medical advice. Your treating clinician decides eligibility, treatment and dosing. For trouble breathing, throat swelling, faintness or a suspected severe allergic reaction, use epinephrine if prescribed and call 911.
General information, not a substitute for your prescriber’s advice. In an emergency, call 911.
Sources
Where the facts come from
Sources
- ACAAI: Allergy immunotherapy
- Radulovic S et al. Cochrane review of sublingual immunotherapy, 60 trials (PMID 21154351)
- Canonica GW et al. Sublingual immunotherapy: World Allergy Organization position paper 2013 update (PMID 24679069)
- Seidman MD et al. Clinical Practice Guideline: Allergic Rhinitis. Otolaryngol Head Neck Surg 2015 (PMID 25644617)
- AAAAI/ACAAI sublingual immunotherapy practice parameter update, 2017 (PMID 28284533)
- Dretzke J et al. SCIT vs SLIT indirect comparison, J Allergy Clin Immunol 2013 (PMID 23557834)
- Kiel MA et al. J Allergy Clin Immunol 2013 — real-life persistence with SCIT and SLIT, 6,486 patients (PMID 23651609)
- Tharpe C et al. Front Allergy 2026 — 2,897-patient telemedicine SLIT cohort (PMID 42358593)
- Tharpe C et al. Allergy Asthma Clin Immunol 2026 — safety of telemedicine SLIT, 13,584 patients, 18,398 patient-years (doi:10.1186/s13223-026-01079-1)
- Janz TA et al. Ear Nose Throat J 2024 — side effects of sublingual immunotherapy, meta-analysis of 26 trials, 7,827 patients (PMID 38840522)
- FDA: Grastek (Timothy grass pollen allergen extract) product page and prescribing information
- FDA: Oralair (five-grass pollen allergen extract) product page
- FDA: Ragwitek (short ragweed pollen allergen extract) product page
- FDA: Odactra (house dust mite allergen extract) product page
- ACAAI: Immunotherapy with allergy tablets
- Cox L et al. Allergen immunotherapy: a practice parameter third update. J Allergy Clin Immunol 2011 (PMID 21122901)
- Curex canonical pricing, client commercial terms as of 2026-10-12
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