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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Allergy and Immunology

Altering the Course: Allergen Immunotherapy (AIT)

At a Glance

Allergen immunotherapy (AIT) is a treatment for allergic rhinitis that retrains the immune system to stop overreacting to allergens. Available as in-office shots or at-home drops, AIT requires a 3 to 5-year commitment but provides lasting relief and can prevent asthma in children.

While most allergy treatments only mask your symptoms, Allergen Immunotherapy (AIT) is unique because it is a disease-modifying treatment [1]. This means it aims to “retrain” your immune system to stop overreacting to allergens, addressing the root cause of your condition rather than just its effects [2][3].

How Immunotherapy Retrains the Immune System

AIT works through a process called immune tolerance [4]. By exposing your body to gradually increasing amounts of an allergen, the treatment helps produce specialized immune cells and “blocking” antibodies that act to “turn off” the allergic response [5][6].

Preventing the “Atopic March”

One of the most powerful benefits of AIT is its potential to alter the course of a person’s health over a lifetime. This is particularly important for children and adolescents. Research shows that AIT can:

  • Prevent Asthma: It significantly reduces the risk of children with allergic rhinitis going on to develop asthma [7][8].
  • Stop New Sensitizations: It can prevent the body from developing new allergies to different triggers [9].
  • Sustain Long-Term Relief: When completed correctly, the benefits of AIT can last for many years after the treatment has stopped [10][11].

Comparing Your Options: SCIT and SLIT

There are two primary ways to receive immunotherapy, and the choice often depends on your lifestyle and preferences.

Feature SCIT (Subcutaneous/Shots) SLIT (Sublingual/Drops or Tablets)
Administration Injections given in a medical clinic [12]. A tablet or drop dissolved under the tongue at home [12].
Frequency Typically weekly during “build-up,” then monthly for maintenance [13]. Usually a daily dose [14].
Pros May have a slightly faster onset of effect for some patients [15]. No needles; superior safety profile with a lower risk of systemic reactions [12][16].
Cons Requires frequent office visits and a waiting period after the shot to monitor for reactions [12]. Requires strict daily discipline to ensure the dose is not missed [17].

The Timeline for Success

Immunotherapy is a marathon, not a sprint. To achieve long-term tolerance—where your symptoms remain minimal even after you stop treatment—most international guidelines recommend a minimum duration of 3 to 5 years [11][18]. While you may begin to feel better within the first several months, stopping too early may cause your allergies to return [11].

Common questions in this guide

How does allergen immunotherapy (AIT) work?
Allergen immunotherapy works by gradually exposing your body to increasing amounts of an allergen. This helps your body produce specialized immune cells that turn off the allergic response and build long-term tolerance.
What is the difference between allergy shots and allergy drops?
Allergy shots (SCIT) are injections given weekly or monthly at a medical clinic. Allergy drops or tablets (SLIT) are taken daily under the tongue at home, offering a needle-free option with a lower risk of severe allergic reactions.
Can immunotherapy prevent asthma in children?
Yes, research shows that allergen immunotherapy can significantly reduce the risk of children with allergic rhinitis developing asthma. It can also prevent the body from developing new allergies to different triggers.
How long does allergen immunotherapy take to work?
While you may begin to feel symptom relief within the first several months, a full course of treatment is a marathon. Most guidelines recommend continuing immunotherapy for three to five years to achieve long-term success.
What happens if I stop allergen immunotherapy early?
Stopping immunotherapy before the recommended three to five years may cause your allergy symptoms to return. Completing the full treatment duration is necessary to ensure long-lasting tolerance to your allergy triggers.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Am I (or is my child) a good candidate for allergen immunotherapy based on my specific allergy triggers?
  2. 2.What is the risk of a systemic reaction for me specifically, and how do we prepare for it?
  3. 3.How soon can I expect to see a reduction in my daily allergy medications after starting AIT?
  4. 4.If we choose SLIT, how do we ensure the first dose is administered safely, and what is the protocol for at-home use?
  5. 5.Given my allergy profile, what is the best estimate for how many years I would need to continue AIT?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Current treatment strategies for seasonal allergic rhinitis: where are we heading?

    Ridolo E, Incorvaia C, Pucciarini F, et al.

    Clinical and molecular allergy : CMA 2022; (20(1)):9 doi:10.1186/s12948-022-00176-x.

    PMID: 35948975
  2. 2

    Allergen Immunotherapy for the Prevention and Treatment of Asthma.

    Batard T, Taillé C, Guilleminault L, et al.

    Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology 2025; (55(2)):111-141 doi:10.1111/cea.14575.

    PMID: 39363801
  3. 3

    Biological mechanisms underlying the clinical effects of allergen-specific immunotherapy in asthmatic children.

    Pelaia C, Vatrella A, Lombardo N, et al.

    Expert opinion on biological therapy 2018; (18(2)):197-204 doi:10.1080/14712598.2018.1402003.

    PMID: 29113525
  4. 4

    Der p 1-specific regulatory T-cell response during house dust mite allergen immunotherapy.

    Boonpiyathad T, Sokolowska M, Morita H, et al.

    Allergy 2019; (74(5)):976-985 doi:10.1111/all.13684.

    PMID: 30485456
  5. 5

    The role of Treg cell subsets in allergic disease.

    Boonpiyathad T, Sözener ZC, Akdis M, Akdis CA

    Asian Pacific journal of allergy and immunology 2020; (38(3)):139-149 doi:10.12932/AP-030220-0754.

    PMID: 32563231
  6. 6

    Induction of IgG2 and IgG4 B-cell memory following sublingual immunotherapy for ryegrass pollen allergy.

    Heeringa JJ, McKenzie CI, Varese N, et al.

    Allergy 2020; (75(5)):1121-1132 doi:10.1111/all.14073.

    PMID: 31587307
  7. 7

    Impact of liquid sublingual immunotherapy on asthma onset and progression in patients with allergic rhinitis: a nationwide population-based study (EfficAPSI study).

    Demoly P, Molimard M, Bergmann JF, et al.

    The Lancet regional health. Europe 2024; (41()):100915 doi:10.1016/j.lanepe.2024.100915.

    PMID: 38707866
  8. 8

    Allergen immunotherapy for asthma prevention: A systematic review and meta-analysis of randomized and non-randomized controlled studies.

    Farraia M, Paciência I, Castro Mendes F, et al.

    Allergy 2022; (77(6)):1719-1735 doi:10.1111/all.15295.

    PMID: 35342949
  9. 9

    Effect of Dermatophagoides pteronyssinus Immunotherapy on Upper and Lower Airway Eosinophilic Inflammatory Response to Nasal Allergen Challenge.

    Huang R, Qin R, Hu Q, et al.

    Allergy, asthma & immunology research 2020; (12(5)):844-858 doi:10.4168/aair.2020.12.5.844.

    PMID: 32638564
  10. 10

    Changes in CD4+CD25+FoxP3+ Regulatory T Cells and Serum Cytokines in Sublingual and Subcutaneous Immunotherapy in Allergic Rhinitis with or without Asthma.

    Xian M, Feng M, Dong Y, et al.

    International archives of allergy and immunology 2020; (181(1)):71-80 doi:10.1159/000503143.

    PMID: 31722337
  11. 11

    Allergen immunotherapy for long-term tolerance and prevention.

    Penagos M, Durham SR

    The Journal of allergy and clinical immunology 2022; (149(3)):802-811 doi:10.1016/j.jaci.2022.01.007.

    PMID: 35085663
  12. 12

    Aeroallergen immunotherapy update: Developments since the third Practice Parameter.

    Bernstein DI

    Allergy and asthma proceedings 2025; (46(6)):450-454 doi:10.2500/aap.2025.46.250067.

    PMID: 41152677
  13. 13

    Efficacy and Safety of Sublingual and Subcutaneous Immunotherapy in Children with Allergic Rhinitis: A Systematic Review of Randomized Trials Including Direct and Indirect Comparisons.

    Asiri A, Alzahrani F, Ismail GM, et al.

    International journal of general medicine 2025; (18()):7037-7047 doi:10.2147/IJGM.S547338.

    PMID: 41278015
  14. 14

    Degree of fear of needles and preferred allergy immunotherapy treatment among children with allergic rhinitis: caregiver survey results.

    Rance K, Blaiss M, Gupta P, et al.

    Frontiers in pediatrics 2024; (12()):1447619 doi:10.3389/fped.2024.1447619.

    PMID: 39156023
  15. 15

    Efficacy and safety of allergen-specific immunotherapy for allergic asthma: a meta-analysis comparing sublingual and subcutaneous routes across allergen types and age groups.

    Yin W, Zeng W, Li Y, et al.

    Annals of medicine 2026; (58(1)):2635778 doi:10.1080/07853890.2026.2635778.

    PMID: 41784325
  16. 16

    Subcutaneous and Sublingual Immunotherapy in Allergic Asthma in Children.

    Tsabouri S, Mavroudi A, Feketea G, Guibas GV

    Frontiers in pediatrics 2017; (5()):82 doi:10.3389/fped.2017.00082.

    PMID: 28484690
  17. 17

    Dropouts From Sublingual Immunotherapy and the Transition to Subcutaneous Immunotherapy in House Dust Mite-Sensitized Allergic Rhinitis Patients.

    Chen H, Gong GQ, Ding M, et al.

    Frontiers in allergy 2021; (2()):810133 doi:10.3389/falgy.2021.810133.

    PMID: 35386972
  18. 18

    Duration of allergen immunotherapy for inhalant allergy.

    Penagos M, Durham SR

    Current opinion in allergy and clinical immunology 2019; (19(6)):594-605 doi:10.1097/ACI.0000000000000585.

    PMID: 31464717

This page provides educational information about allergen immunotherapy (AIT) for allergic rhinitis. It does not replace professional medical advice. Always consult with a board-certified allergist to determine the safest and most effective treatment plan for you or your child.

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