Allergy drops and tablets (sublingual immunotherapy, or SLIT) and allergy shots (subcutaneous immunotherapy) both work the same way: regular, gradually controlled doses of an allergen teach your immune system to react less. Both treat the allergy itself rather than just the symptoms, and both take years. The differences are in how they’re given, which allergens they cover, and what’s FDA approved.
This guide compares the two side by side, explains why liquid drops are used “off-label” in the U.S., and covers safety. For more, see our allergy treatment guides.
Jump to: Quick answer · Side by side · FDA-approved tablets · What about liquid drops? · How allergy shots work · Which works better? · FAQ
Quick answer
- Neither is proven better overall. A large UK review found both shots and under-the-tongue immunotherapy beat placebo, but indirect comparisons didn’t clearly favor either one.
- Tablets are the only FDA-approved under-the-tongue option, for grass, ragweed and dust mite allergy, ages 5 to 65.
- Liquid allergy drops are not FDA approved and are used off-label in the U.S., according to the American College of Allergy, Asthma and Immunology (ACAAI).
- Shots cover more allergens, including tree, grass and weed pollens, dust mites, mold, pet dander and insect stings (Mayo Clinic).
- Both take years: shots usually run 3 to 5 years; grass tablets are taken daily for three years for lasting benefit.
Drops and tablets vs shots, side by side
| Under the tongue (SLIT tablets) | Allergy shots | |
|---|---|---|
| How it’s given | Tablet dissolves under the tongue, once a day at home after the first dose | Injection in the upper arm at a clinic |
| Allergens covered | FDA-approved tablets for grass pollen, short ragweed and house dust mite | Pollens, dust mites, cockroach, mold, pet dander and stinging insects |
| Schedule | Daily; pollen tablets start 12 weeks (Oralair: at least 4 months) before the season | Build-up 3 to 6 months, 1 to 3 shots a week; then about once a month |
| How long | Grass tablets: daily for three years for benefit that lasts after stopping | Maintenance for 3 to 5 years or longer |
| Observation | At least 30 minutes after the first dose, in the doctor’s office | 30 minutes after every shot |
| Epinephrine | Auto-injector prescribed (boxed warning) | Used if a serious reaction happens; ask whether you need one |
| Common side effects | Itching in the mouth, tongue or ears, mouth swelling, throat irritation | Swelling or irritation where the shot was given |
Sources: the AAAAI tablet guide, the Grastek prescribing information, and Mayo Clinic’s allergy shots page.
The four FDA-approved allergy tablets
According to the American Academy of Allergy, Asthma and Immunology (AAAAI), all four are approved for ages 5 to 65:
- Grastek: Timothy and related grasses. One tablet a day, starting 12 weeks before grass season.
- Oralair: a mix of five grasses (sweet vernal, orchard, perennial rye, Timothy and Kentucky blue). Start at least 4 months before grass season.
- Ragwitek: short ragweed. Start 12 weeks before ragweed season.
- Odactra: house dust mite. Once a day, year-round.
Each one carries an FDA boxed warning about severe allergic reactions. The Grastek label, for example, says the first dose must be given under a doctor’s supervision with at least 30 minutes of observation, that an epinephrine auto-injector should be prescribed, and that it shouldn’t be used by people with severe, unstable or uncontrolled asthma or a history of eosinophilic esophagitis.
Tablets only help if the allergen they contain is what you react to. If dust mites are your trigger, see dust mite allergy vaccine research and how dust mite allergy is diagnosed.
What about liquid allergy drops?
Some U.S. allergists prescribe liquid drops mixed from allergen extracts. The ACAAI notes that tablets are the only FDA-approved sublingual therapy and that liquid drops are not FDA approved, so they’re used off-label. That means dosing isn’t standardized by an FDA label, and insurance coverage may differ. If you’re offered drops, ask your allergist which allergens are included, what dose they use and what evidence supports it.
How allergy shots work
Mayo Clinic explains that shots go through two phases:
- Build-up phase: usually 3 to 6 months, with shots 1 to 3 times a week and the dose rising each time.
- Maintenance phase: about one shot a month for 3 to 5 years or longer.
Symptoms usually improve during the first year, with the most noticeable improvement often in the second. Some people stay symptom-free after stopping; others need ongoing shots. Shots aren’t used for food allergies or long-lasting hives. You’ll wait in the clinic for 30 minutes after each shot, because serious reactions, though less common, can happen.
Which works better?
A 2013 UK Health Technology Assessment reviewed placebo-controlled trials of both routes for seasonal allergic rhinitis. Both shots and under-the-tongue immunotherapy reduced symptoms compared with placebo, but indirect comparisons didn’t give conclusive results in favor of either one. The authors called for more head-to-head research.
So the choice usually comes down to practical factors:
- Your allergens: tablets exist for only grass, ragweed and dust mite; shots can combine many allergens and treat insect sting allergy.
- Time and travel: tablets are taken at home; shots need regular clinic visits.
- Daily routine: tablets only work if you take them every day.
- Health conditions: severe or uncontrolled asthma rules out tablets and needs careful review for shots.
An allergist can test exactly what you react to and help you decide. Until then, see using a neti pot safely and how to avoid pollen. For drops used in food allergy research, read under-the-tongue therapy for milk allergy.
This guide is general information, not medical advice. Read our medical disclaimer.
Frequently asked questions
Are allergy drops better than allergy shots?
Not clearly. A large UK review found both work better than placebo, but couldn’t show that one route beats the other. The right choice depends on your allergens, schedule and health.
Are allergy drops FDA approved?
Liquid drops are not; they’re used off-label in the U.S. Four under-the-tongue tablets are FDA approved: Grastek, Oralair, Ragwitek and Odactra.
How long do you take allergy drops or tablets?
Grass tablets such as Grastek can be taken daily for three consecutive years for benefit that lasts after stopping. Pollen tablets start 12 weeks or more before the season.
What are the side effects of allergy tablets?
The most common are itching of the mouth, tongue or ears, mouth swelling and throat irritation. Severe allergic reactions are possible, which is why the first dose is given in a doctor’s office and epinephrine is prescribed.
How long do allergy shots take to work?
Mayo Clinic says symptoms usually improve during the first year, with the most noticeable improvement often in the second year of treatment.
Sources
- American Academy of Allergy, Asthma and Immunology. Sublingual immunotherapy (SLIT) allergy tablets. Last updated March 2026.
- U.S. Food and Drug Administration. Grastek prescribing information. Revised March 2022.
- American College of Allergy, Asthma and Immunology. Allergy immunotherapy.
- Mayo Clinic Staff. Allergy shots. April 13, 2024.
- Meadows A, Kaambwa B, Novielli N, et al. A systematic review and economic evaluation of subcutaneous and sublingual allergen immunotherapy in adults and children with seasonal allergic rhinitis. Health Technol Assess. 2013;17(27).
Last reviewed: October 21, 2026.
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