Sublingual immunotherapy for Hay Fever SLIT
Expert Hay Fever Treatment at The London Allergy and Immunology Centre, Harley Street Allergy Clinic
If you suffer from hay fever, effective long-term treatment is available. The London Allergy and Immunology Centre specialises in Allergy Specific Immunotherapy (SIT), a transformative approach that treats the underlying cause of your allergies, not just the symptoms.
What is Allergy Immunotherapy (Desensitisation)?
Allergen Specific Immunotherapy (SIT) is a proven method to desensitise your immune system to allergens. It is used to treat allergic rhinitis (hay fever), allergic asthma (controlled with treatment) caused by airborne allergens, and venom allergies (bee/wasp stings).
Treatment used to be available in two forms:
· Sublingual Immunotherapy (SLIT): Drops or tablets taken daily under the tongue.
· Subcutaneous Immunotherapy (SCIT): Regular injections (“allergy shots”) have been fased out during COVID and are no longer used.
Our Treatment Programme
For optimal results, immunotherapy is a long-term commitment. Treatment is typically started after the grass pollen season ends (usually no later than four months before the next season begins to get benefits for the upcoming season) and is continued year-round for a minimum of three years.
It is possible to desensitise patients to a wide range of allergens via the sublingual route, including:
· Grasses (e.g., Timothy grass, Ryegrass)
· Trees (e.g., Birch, Alder, Hazel Plane)
· Weeds (e.g., Ragweed, Mugwort)
· House Dust Mite (e.g., D Farinae and D Pteronissinus as well as Tropical Mites)
· Cats
· Dogs
Only allergy consultant can recommend this treatment after assessment of your history and test results.
Please register as a new patient.
Book a Consultation with Our Specialists
If you are interested in exploring your treatment options, we invite you to book a consultation with one of our expert consultants. We welcome new private patients.
To register as a new patient, please book an appointment online. After receiving your request, our practice manager will contact you within one business day. Our current waiting time to see a consultant is typically less than one week.
International Patients Welcome
We accept patients who have started their immunotherapy treatment elsewhere (e.g., the US, EU, Australia, New Zealand) and are moving to London or the surrounding areas. We can continue your course of treatment as SLIT subject to vaccine availability. Please note we might need to contact your previous doctor to coordinate your care or will need paperwork from your doctor.
If you are interested to see allergy consultant and discuss options for hay fever treatment please book an appointment.
Science behind immunotherapy:
Please see below detailed overview of mechanistic advances in allergen immunotherapy (AIT), integrating insights into IL-10–producing innate lymphoid cells (ILCs), regulatory lymphocyte subsets, antibody isotype shifts, epigenetics, and biomarker profiling.
Recent mechanistic advances in allergen immunotherapy (SIT) underline the continual evolution of this intervention within the domain of allergic disease management.
Both subcutaneous (SCIT) and sublingual (SLIT) immunotherapy have been demonstrated to induce regulatory immune responses, specifically implicating IL-10-producing innate lymphoid cells (ILCs), dendritic cells (DCs), and several regulatory subsets of T and B lymphocytes.
Clinical findings highlighted the restoration of epithelial cell function and the modulation of T lymphocyte responses as central indicators of successful immunotherapeutic outcomes.
A prospective examination showed a correlation between IL-10-producing ILCs and clinical improvement in nasal symptom scores.
Application of single-cell RNA sequencing identified upregulation of the retinoic acid pathway related to IL-10 production among SLIT responders.
Distinct immune pathway modulation and variations in antibody isotype profiles—such as greater IgG4 production in SCIT and elevated IgA1 in SLIT—were observed, suggesting differential mechanistic endpoints depending on the mode of immunotherapy.
Furthermore, epigenetic analyses signified substantial regulatory shifts in chromatin accessibility within T follicular helper (TFH) and follicular regulatory (TFR) lymphocytes following SIT.
The implementation of biomarkers in evaluating response to immunotherapy is an emerging theme within allergy and immunology research.
The use statistics logistic regression, random forest classifiers, support vector machines, and neural networks, is gaining prominence for diagnostic purposes, cohort stratification, disease trajectory prediction, and assessment of immunological tolerance.
Consolidation of diverse datasets—including skin prick tests, component-resolved diagnostic panels, clinical history, single-cell multi-omics, immunoprofiling, and serological analyses—has enabled in-depth investigation.
The GRAS study, a multi-year randomised controlled trial with SCIT, SLIT, and placebo arms, exemplified this approach by encompassing 106 patients and rigorous longitudinal acquisition of both clinical and immunological data.
Analyses indicated that biomarker profiles with predictive value for treatment response varied by year, indicating the absence of a universal biomarker and the requirement for tailored panels at different time points for each immunotherapy modality.
From a clinical standpoint, the establishment of consensus outcome measures—such as total nasal symptom scores (TNSS), visual analogue scales (VAS), and combined symptom and medication scores—remains essential for harmonising trials and clinical practice.
Integration of immunophenotyping, genomic, proteomic, serological, and tissue-based data is crucial in stratifying patients and informing personalised treatment paradigms.
The issue of compliance with immunotherapeutic regimens, which fundamentally affects clinical tolerance and efficacy.
Ongoing research, alongside forthcoming real-world evidence analyses, aims to validate and further improve these strategies.
References:
- Haspeslagh E, Hammad H, Akdis M, Akdis CA, Lambrecht BN. Induction of IL-10-producing type 2 innate lymphoid cells by allergen immunotherapy is associated with clinical response. Immunity.2025;58(8):1736-1752.e9. doi:10.1016/j.immuni.2025.07.002. PMID: 40695293
- Ohashi Y, Furusawa E, Tamari M, et al. Single-cell immunoprofiling after immunotherapy for allergic rhinitis revealed a key molecule in good responders. Allergy. 2022;77(12):3704-3716. doi:10.1111/all.15502. PMID: 35863510
- Martínez-Aranguren R, San Segundo D, Ruiz-León B, et al. Single-cell RNA sequencing identifies precise tolerogenic cellular and molecular pathways induced by depigmented-polymerized grass pollen allergen extract. Allergy. 2023;78(6):1449-1465. doi:10.1111/all.15593. PMID: 36649758
- Novak N, Kraft S, Maurer M, et al. Mechanisms of allergen immunotherapy in allergic rhinitis—review. J Clin Med. 2023;12(11):3776. doi:10.3390/jcm12113776. PMID: 37996041
- Shamji MH, Durham SR. Mechanisms and biomarkers of successful allergen-specific immunotherapy for allergic rhinitis and asthma. J Allergy Clin Immunol. 2023;152(3):519-531. doi:10.1016/j.jaci.2022.11.024. PMID: 36452016
- Chen M, Li H, Yang Z, et al. AI-driven biomarker discovery and personalized allergy treatment. Front Immunol. 2025;16:1462442. doi:10.3389/fimmu.2025.1462442. PMID: 40459653
- Wong GWK, Custovic A, Agache I, et al. Future of allergy and immunology: Is artificial intelligence the key to better care? Allergy. 2024;79(9):2121-2134. doi:10.1111/all.16474. PMID: 39428098