Allergy immunotherapy is the only allergy treatment that changes how your immune system reacts, rather than just easing symptoms. It takes commitment, usually years. This guide compares allergy shots and under-the-tongue tablets, explains the schedule and how long it takes to work, and covers who it helps and how to stay safe.
It draws on the American Academy of Allergy, Asthma & Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the FDA and Mayo Clinic. It is general information, not medical advice.
Key takeaways
- Allergy shots are the most common and most effective form of immunotherapy (ACAAI).
- Expect 3 to 6 months of build-up, then maintenance every 2 to 4 weeks for 3 to 5 years (AAAAI).
- It can take up to 12 months on maintenance to notice improvement (AAAAI).
- Four FDA-approved tablets treat certain grass and ragweed pollens and dust mites (FDA).
- You wait at least 30 minutes after each shot in case of a serious reaction (Mayo Clinic).
What immunotherapy is
Allergen immunotherapy gives you gradually larger doses of the allergens you react to, so your immune system becomes less sensitive to them (Mayo Clinic). Unlike antihistamines or nasal steroids, which relieve symptoms, it targets the allergic response itself and can give lasting relief (ACAAI).
Shots vs. tablets
| Allergy shots (SCIT) | Sublingual tablets (SLIT) | |
|---|---|---|
| How it is given | Injections, usually in the upper arm, at a doctor’s office | A tablet dissolved under the tongue every day, at home after the first dose |
| What it treats | Pollen, dust mites, mold, pet dander, cockroaches and stinging insects | Only certain grass and ragweed pollens and house dust mites |
| Schedule | Build-up for 3 to 6 months, then maintenance shots every 2 to 4 weeks | Daily; pollen tablets start several months before the season, and treatment can continue for up to 3 years |
| Safety | 30-minute wait in the office after each shot | First dose under medical supervision with 30 minutes of observation; epinephrine is prescribed |
Allergy shots are the most common and most effective form of immunotherapy (ACAAI). The FDA has approved four sublingual tablets: Grastek, Oralair, Odactra and Ragwitek (FDA). Allergy drops under the tongue are not FDA-approved and are used off-label in the U.S. (ACAAI).
The treatment schedule
- Build-up phase: one to two shots a week for about 3 to 6 months while the dose increases (AAAAI).
- Maintenance phase: a shot every 2 to 4 weeks. If it is working, maintenance usually continues for 3 to 5 years (AAAAI).
It can take up to 12 months on maintenance to notice improvement (AAAAI). If you skip doses, you may need to go back to a lower dose (Mayo Clinic).
Who it helps
Allergy shots can treat (Mayo Clinic):
- Indoor allergies to cockroaches, dust mites, mold and pet dander
- Insect sting allergies to bees, hornets, wasps and yellow jackets
- Seasonal allergies and allergic asthma from tree, grass and weed pollen
Shots aren’t available for food allergies or chronic hives (Mayo Clinic). In children, immunotherapy can help prevent new allergies and the progression from allergic rhinitis to asthma (AAAAI). It may be a good choice if medicines don’t control your symptoms, cause side effects, or you want to cut down on long-term medicine use (Mayo Clinic).
Side effects and safety
The most common reactions are redness, swelling or itching where the shot was given, and sometimes sneezing, nasal congestion or hives (Mayo Clinic). Rarely, a shot can cause anaphylaxis, which usually starts within 30 minutes. That is why you wait in the office for at least 30 minutes after each shot (Mayo Clinic). If you have been prescribed an EpiPen or other epinephrine, keep it with you.
Tell the staff if you feel unwell before a shot, especially if your asthma is acting up, and avoid hard exercise for a few hours afterward (Mayo Clinic).
Getting started
An allergist first confirms your triggers with skin or blood tests (Mayo Clinic). See our allergy testing guide, or allergy testing near me in Florida. For timing around your local season, see pollen near me by city, spring allergies and fall allergies.
Frequently asked questions
How long do allergy shots take to work?
Some people improve during build-up, but it can take up to 12 months on maintenance (AAAAI).
How long does treatment last?
Usually 3 to 5 years of maintenance after a 3- to 6-month build-up (AAAAI).
Are allergy tablets as good as shots?
Shots are the most common and most effective form, but tablets are an option for certain grass, ragweed and dust mite allergies (ACAAI).
Can children get immunotherapy?
Yes. The FDA expanded Odactra, a dust mite tablet, to children 5 and older in 2025 (FDA), and shots may help prevent asthma in children with allergies (AAAAI).
Related reading
Local pollen and allergist guides
Pollen seasons and triggers change by city. See what is in the air near me and where to find an allergist.
City pollen guides
State guides
Sources
Originally written by Madiha Ather Hashmi (2020). Updated November 2026 with current sources.
This page is for general information only and is not medical advice. Talk with your doctor or pharmacist about your symptoms and before starting, stopping or combining any medicine.