Sublingual Immunotherapy Drops
Long-term specialist allergy treatment using sublingual drops under the tongue, designed to reduce the allergic response rather than simply mask symptoms for a few hours.
Sublingual immunotherapy, often called SLIT, is different from standard allergy medicines. Rather than simply easing symptoms for a short period, it works by gradually teaching the immune system to become less reactive to the allergen itself.
This is why allergen immunotherapy is widely regarded as the only disease-modifying treatment for IgE-mediated respiratory allergy. In suitable patients, sublingual drops may reduce symptoms, lower the need for medication, improve day-to-day control, and offer benefits that continue after the treatment course has finished.
Modern literature continues to support a more personalised approach to SLIT, combining careful clinical history, targeted allergy testing, shared decision-making, and ongoing follow-up to improve adherence and long-term outcomes.
Specialist assessment is important because sublingual immunotherapy is only suitable for selected patients and should be matched carefully to the allergy pattern, symptom burden, clinical history, and treatment goals.
Sublingual immunotherapy (SLIT) for allergies including pollen, mould (Alternaria), dust mite and animal dander at our London clinic
Targets the allergic process itself
Typical full treatment duration
Treatment taken under the tongue
Personalised specialist assessment
What makes sublingual drops different?
Most allergy medicines are designed to control symptoms such as sneezing, itching, watery eyes, nasal blockage or wheeze. Sublingual immunotherapy goes further by acting on the immune response that drives the allergy.
- It aims to improve tolerance to the allergen over time
- It may reduce day-to-day symptoms and rescue medication use
- It can provide benefit that continues after the treatment course is completed
- It is used as a structured long-term treatment rather than a quick symptom reliever
How long does treatment usually last?
For inhalant allergies such as pollen or house dust mite, a full treatment course with sublingual drops is commonly planned for at least 3 years. This duration is important because it is linked to the best chance of achieving long-term clinical benefit.
In practice, SLIT is usually considered when symptoms remain troublesome, when medicines are not giving enough relief, when symptoms recur season after season, or when a patient wants a more disease-focused long-term treatment strategy.
How sublingual immunotherapy drops work
Immune regulation
The treatment is associated with increased regulatory immune responses and a reduction in the exaggerated allergic response that drives symptoms.
Blocking antibodies
SLIT is linked with increased allergen-specific blocking antibodies, especially IgG4, which may help reduce allergen-triggered reactivity over time.
Clinical effect
As tolerance develops, symptoms may become less frequent, less severe and easier to control, with lower dependence on symptom-relieving medicines in suitable patients.
How SLIT drops are taken
- Under the tongue – the prescribed drops are placed under the tongue as advised by your specialist
- Regular dosing – treatment needs to be taken consistently for the planned course
- Long-term approach – benefit develops gradually and depends on adherence
- Specialist monitoring – progress, tolerance and treatment response should be reviewed over time
The exact schedule, dose escalation and maintenance plan depend on the allergen, the product used, the patient’s age, safety factors, and the specialist prescription.
Potential benefits of SLIT drops
- Reduced allergic rhinitis and rhinoconjunctivitis symptoms in suitable patients
- Lower use of antihistamines and other symptom-relieving medicines in real-world studies
- Improved quality of life and day-to-day control
- Potential disease-modifying effect beyond the active treatment period
- A personalised, consultant-led strategy for long-term allergy management
Who may be suitable for sublingual drops?
Confirmed allergy pattern
SLIT is usually considered when there is a convincing link between symptoms and a clinically relevant allergen, supported by a careful history and appropriate testing.
Persistent or recurrent symptoms
It may be appropriate for patients whose symptoms remain significant despite standard treatment, or for those with predictable seasonal or perennial symptoms that continue to affect quality of life.
Commitment to treatment
Because treatment is long term, good adherence is essential. Recent literature increasingly highlights patient-centred follow-up, digital support tools and regular review as important parts of successful SLIT care.
Specialist selection
Not every positive allergy test means immunotherapy is appropriate. The decision should be based on the whole clinical picture, including the allergy relevance, symptom burden, coexisting conditions and treatment goals.
Safety and practical points
Local side effects
Mild local reactions such as mouth or throat irritation can occur, especially early in treatment. These are commonly transient, but all treatment should be used exactly as prescribed and discussed with your specialist if symptoms are troublesome.
Consistency matters
SLIT is not an occasional treatment. Good adherence is a major factor in clinical success, which is why regular follow-up and clear treatment plans are important.
Ongoing review
Modern allergy care increasingly uses structured follow-up, symptom tracking and patient-reported outcomes to assess whether treatment is helping and whether the plan should continue as intended.
Modern developments in SLIT
Real-world evidence
Recent real-world studies of liquid SLIT have reported reductions in allergy medication use and healthcare resource use, with continued benefit seen beyond the active treatment period in some populations.
Asthma-related outcomes
Emerging evidence suggests that, in selected respiratory allergy populations, liquid SLIT may be associated with lower risk of asthma worsening and may help slow disease progression, although suitability still needs individual specialist assessment.
Patient-centred monitoring
Newer studies increasingly focus on patient-reported benefit, quality of life and treatment expectations, reflecting a shift toward more personalised and practical long-term allergy care.
Precision allergy diagnosis
Molecular allergy testing and more detailed sensitisation profiling may help identify the most clinically relevant allergens and support more tailored treatment decisions.
Looking for sublingual immunotherapy drops in London?
At London Allergy and Immunology Centre, we provide consultant-led allergy assessment, detailed testing, and personalised advice on whether sublingual immunotherapy drops may be suitable for your symptoms, diagnosis and long-term treatment goals.
We can help assess hay fever, house dust mite allergy and other relevant inhalant allergies, and discuss the most appropriate next steps for long-term management with SLIT.
Selected references
- EAACI Guidelines on Allergen Immunotherapy: Allergic Rhinoconjunctivitis.
- ARIA-EAACI 2024–2025 revision and related methodology papers published in 2025–2026.
- Devillier P, et al. Impact of liquid sublingual immunotherapy on health care resource use in allergic rhinitis and asthma in the real-world EfficAPSI study. 2025.
- Caimmi D, et al. Patient-perceived benefits of named-patient product sublingual immunotherapy in allergic rhinitis and asthma: ERAPP real-world cohort study. 2026.
- Zielen S, et al. Long-term impact of birch-family liquid sublingual immunotherapy on respiratory allergy: a real-world study. 2025.
- Comprehensive review and meta-analytical evidence for house dust mite sublingual immunotherapy in allergic rhinoconjunctivitis. 2026.
- Recent literature on biomarkers, adherence, digital monitoring and personalised allergy diagnosis in immunotherapy care pathways.
This page is intended for general educational purposes and does not replace individual medical advice.