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ALEX³ postal allergy test kit, yellow-capped blood sample tube and sublingual spray beside grass and birch, with London in the background.

Hay fever that keeps coming back: a patient guide to testing and sublingual immunotherapy

8th October 2026

Hay fever and pollen allergy · Updated

If sneezing, itchy eyes and a blocked nose return every spring or summer despite treatment, a specialist assessment can help identify your triggers and review your options. This guide explains hay fever testing in London and sublingual immunotherapy (SLIT), with a focus on treatment administered as a spray under the tongue.

Postal allergy test kit, yellow-capped blood sample tube and sublingual spray beside grass and birch, with the London skyline behind.
Pollen allergy testing and sublingual immunotherapy for hay fever. This generated image is illustrative; kit contents and treatment packaging may differ.

In brief

  • Allergy results need to match your symptoms and exposure; a positive test alone is not a diagnosis.
  • Sublingual immunotherapy aims to reduce sensitivity to a relevant allergen over a course usually lasting at least three years.
  • Benefits depend on the individual preparation, dose, allergen and patient.
  • Asthma must be assessed and adequately controlled before treatment.

Why hay fever symptoms can return each year

Antihistamines, nasal corticosteroid sprays and eye drops can control symptoms, but they do not generally provide lasting changes to your sensitivity to pollen. Symptoms may therefore recur during a new pollen season.

Persistent symptoms can also reflect an unsuitable medicine, inconsistent use, nasal spray technique or an additional diagnosis. Tree pollen often causes symptoms in spring, grass pollen in late spring and summer, and some weed pollens later in the season. The exact timing varies with the plant, weather and location.

What hay fever testing in London involves

  1. A history of your symptoms
    We ask when symptoms begin and end, how they affect sleep and daily life, and whether you also have wheeze, cough or an itchy mouth after certain raw fruits.
  2. Skin prick or specific IgE blood testing
    The choice depends on your history, skin condition and medicines. Skin prick testing usually gives results during the appointment. Specific IgE blood testing may be useful when skin testing is unsuitable. Follow the clinic’s instructions about antihistamines; do not stop prescribed medicines without advice.
  3. Component testing when it can clarify the diagnosis
    Testing individual allergen proteins can help distinguish primary sensitisation from cross-reactivity. Broad tests such as ALEX³ are not necessary for every person with hay fever; your specialist should select testing that answers a clinical question.
  4. Breathing checks where appropriate
    Cough, wheeze or breathlessness may warrant an asthma assessment. An allergy test alone cannot diagnose asthma.
  5. A personalised management plan
    We explain which findings are relevant and discuss symptom control, possible immunotherapy and follow-up.

What does a positive allergy test mean?

A positive skin prick or specific IgE blood test indicates sensitisation. It becomes clinically relevant when it matches your symptoms and exposure. Test results need to be interpreted alongside your medical history.

Read more about
allergy tests available at the clinic.

Hay fever treatment options

Controlling symptoms

  • A nasal corticosteroid spray used consistently, with the correct technique
  • An appropriate antihistamine and, when needed, allergy eye drops
  • Reducing pollen exposure where practical and checking pollen forecasts

Considering immunotherapy

  • Specialist assessment when symptoms remain troublesome despite appropriate treatment
  • Allergen-specific treatment selected to match the clinical diagnosis
  • Continued symptom medicines and regular review where needed

Allergen immunotherapy may be considered when clinically relevant allergy is confirmed and symptoms remain significant despite appropriate treatment. It requires a discussion of expected benefits, risks and the commitment involved.
[1]
[8]

Sublingual immunotherapy: what to expect

Sublingual immunotherapy delivers a prescribed allergen preparation under the tongue. This page focuses on sprays. Drops, tablets and injection immunotherapy also exist, but preparations and routes are not interchangeable. Evidence for one product does not automatically establish the effectiveness of another.

Your clinic will arrange supervised initiation and explain the prescribed dose, administration method and monitoring. Follow the instructions for your own preparation, including how long to hold it under the tongue. Suitable patients then continue treatment at home with specialist follow-up.

A course usually lasts at least three years when the aim is sustained benefit. The schedule and total duration depend on the preparation and clinical response.
[1]

First months

Mouth itching or tingling can occur. Report troublesome reactions and follow the advice given at initiation. Continue your usual medicines unless your clinician advises otherwise.

First pollen season

Some people notice fewer symptoms or reduced medicine use, while others take longer to respond. Record symptoms, pollen exposure and medicine use to help assess progress.

Years two and three

Regular reviews assess benefit, side effects, adherence and asthma control. Your specialist will decide whether continuing treatment remains appropriate.

What research shows about immunotherapy

Research supports allergen immunotherapy for selected patients. The preparation, treatment route and study population matter when applying findings to an individual patient.

Benefits during a third year of grass pollen treatment

A small extension study of a high-dose six-grass sublingual preparation reported further improvement in symptom and medication scores during the third year, with more well days. No serious adverse events were reported in that study.
[4]

Study limitations:
This was a small study of one preparation; it does not establish the results of every grass pollen spray.

Evidence for specific liquid sublingual preparations

Two 2025 systematic reviews reported improvements in symptom and medication scores with the liquid preparations studied. One review assessed index-of-reactivity liquid products; the other examined a five-grass liquid formulation.
[2]
[3]
[9]

Study limitations:
These reviews are product-specific. Evidence for the preparations studied cannot be assumed to apply to all liquids or sprays. The first review also has a published correction.

Long-term follow-up in house dust mite allergy

A 2026 analysis of a 15-year follow-up study found less progression to the study-defined asthma outcome in patients who received three to five years of SLIT than in those receiving medicines alone.
[5]

Study limitations:
This was a post hoc analysis of an open-label study in mite-allergic patients with bronchial hyperreactivity. It is not direct evidence that pollen sprays prevent asthma.

Injection immunotherapy in local allergic rhinitis

A 2026 ten-year follow-up compared selected responders to subcutaneous immunotherapy with matched untreated patients. Asthma developed in 8.0% of treated patients versus 40.7% of untreated patients; new sensitisations occurred in 6.3% versus 38.2%.
[6]

Study limitations:
This involved injection immunotherapy, not SLIT, and a specific condition called local allergic rhinitis. Selection of responders and the non-randomised follow-up limit generalisation.

Immunotherapy and allergic asthma

A 2026 meta-analysis included 28 randomised controlled trials assessing allergen immunotherapy for allergic asthma. It reported improvements in symptoms and medication use, with greater average benefit for injection treatment. Systemic reactions were also increased.
[7]

Study limitations:
This does not establish the best route for every patient. Asthma treatment and monitoring must continue; immunotherapy does not replace prescribed inhalers.

Who needs extra care before immunotherapy?

Poorly controlled or severe asthma can make immunotherapy unsuitable. Your specialist will also review your medical history, current illness, mouth problems and medicines, including beta-blockers, because these can affect suitability or the management of a reaction.

Immunotherapy is generally not started during pregnancy. If you become pregnant during an established course, contact your specialist promptly for an individual review rather than changing treatment yourself.

Local mouth or throat symptoms are common with SLIT. Serious allergic reactions are uncommon but possible. Your team should provide instructions for reactions, missed doses, mouth ulcers and restarting after an interruption.

Questions to ask your allergy specialist

  • Which pollen is causing my symptoms, and how do the tests support this?
  • Could better nasal spray technique or a different medicine help?
  • What evidence supports the preparation you are considering?
  • What is the schedule, total duration and cost of the course?
  • How will we assess benefit, and what should I do about missed doses or reactions?

Common questions about hay fever tests and SLIT

Do I need an allergy test before starting immunotherapy?

Usually, yes. Your specialist needs evidence that a particular allergen is relevant to your symptoms. This generally involves skin prick testing or a specific IgE blood test. A positive test alone does not establish a clinical allergy.

When is the best time to start sublingual immunotherapy for hay fever?

The timing depends on the prescribed preparation and your pollen season. Many pollen regimens begin several months before the season, so autumn or winter can be a useful time to arrange an assessment.

Will I still need antihistamines?

You may still need antihistamines, nasal sprays or eye drops, particularly during the first pollen season. Your specialist will review your symptoms and advise on any changes to your medicines.

Is sublingual immunotherapy a cure for hay fever?

It can reduce symptoms and the need for medicines, and some preparations have evidence of benefits after treatment ends. It is not a guaranteed cure, and results vary between people and products.

Can children have sublingual immunotherapy?

Some children may be suitable. A specialist will consider the child’s age, symptoms, asthma control and the evidence and prescribing requirements for the proposed preparation.

Arrange a hay fever assessment in London

Discuss your symptoms, testing needs and treatment options with our specialist team.

This page provides general information and does not replace an individual clinical assessment. If an allergic reaction causes severe breathing difficulty, throat swelling or faintness, call 999. Use your prescribed adrenaline auto-injector if indicated by your emergency action plan.

Sources and further reading

  1. EAACI. Guidelines on allergen immunotherapy: allergic rhinoconjunctivitis. Allergy (2018).
  2. Di Bona et al. Efficacy of index of reactivity-liquid sublingual immunotherapy in allergic rhinoconjunctivitis: systematic review and meta-analysis. Frontiers in Allergy (2025).
  3. Di Bona et al. Efficacy of five-grass pollen liquid sublingual allergen immunotherapy: systematic review and meta-analysis. Journal of Investigational Allergology and Clinical Immunology (2025).
  4. Kuna et al. Sustained clinical efficacy of sublingual immunotherapy with a high-dose grass pollen extract. European Annals of Allergy and Clinical Immunology.
  5. Marogna et al. Long-term effects of SLIT in preventing the development of asthma in allergic rhinitis: revision of 15-year follow-up. World Allergy Organization Journal (2026).
  6. Testera-Montes et al. Long-term effect of allergen immunotherapy in responder local allergic rhinitis patients. Allergy (2026).
  7. Efficacy and safety of allergen-specific immunotherapy for allergic asthma: meta-analysis comparing sublingual and subcutaneous routes. Annals of Medicine (2026).
  8. British Society for Allergy and Clinical Immunology (BSACI). Immunotherapy.
  9. Correction to Di Bona et al., index-of-reactivity liquid SLIT review. Frontiers in Allergy (2025).

FcRn Blockade and IgG Autoantibodies | Immunology Treatment Explained

31st May 2026

Patient Immunology Information

FcRn Blockade and IgG Autoantibodies

A medical explanation of how the neonatal Fc receptor helps IgG antibodies survive in the body, and how FcRn blockade may reduce disease-causing IgG autoantibodies in selected antibody-mediated autoimmune conditions.

Key message

FcRn blockade is a targeted immunological treatment strategy designed to lower immunoglobulin G, known as IgG. It interrupts the recycling system that normally protects IgG from breakdown. In conditions where IgG autoantibodies contribute to inflammation, receptor dysfunction or tissue injury, reducing circulating IgG may help reduce disease activity without broadly suppressing the whole immune system.

Immunology of FcRn-mediated IgG recycling and FcRn blockade, showing antibody recycling under normal conditions and accelerated degradation of pathogenic IgG autoantibodies after FcRn inhibition.

Immunology illustration demonstrating the role of the neonatal Fc receptor (FcRn) in IgG recycling and how FcRn blockade promotes degradation of pathogenic IgG autoantibodies in antibody-mediated autoimmune disease.

What is FcRn?

FcRn stands for neonatal Fc receptor. Despite the word neonatal, FcRn is not only important in newborn babies. It remains active throughout life and is found in several tissues, including vascular endothelial cells, immune cells and epithelial surfaces. Its main role is to regulate the survival of IgG antibodies and albumin in the circulation.

IgG is the most abundant antibody class in the blood. It plays an essential role in protection against infection, long-term immune memory and the response to vaccination. However, in some autoimmune diseases, the immune system produces IgG autoantibodies. These are antibodies that bind to the body’s own proteins. If these IgG autoantibodies are pathogenic, they may activate inflammatory pathways, interfere with normal receptor function, recruit complement, promote tissue injury or disturb normal cell signalling.

How FcRn protects IgG from breakdown

Cells constantly take up small amounts of fluid and proteins from the bloodstream. Many internalised proteins are sent to lysosomes, where they are broken down. IgG is different because FcRn binds to IgG inside acidic endosomes and diverts it away from lysosomal degradation. The IgG is then recycled back to the cell surface and released into the bloodstream.

This recycling process gives IgG a long biological half-life compared with many other circulating proteins. In healthy immunity, this is useful because protective antibodies remain available for longer. In antibody-mediated autoimmunity, the same protective recycling pathway may also prolong the survival of harmful IgG autoantibodies.

The FcRn recycling pathway in simple terms

1. IgG enters cells from the bloodstream.

2. FcRn binds IgG inside acidic endosomes.

3. Bound IgG is protected from lysosomal breakdown.

4. IgG is returned to the bloodstream.

5. This prolongs IgG survival, including the survival of pathogenic IgG autoantibodies.

What is FcRn blockade?

FcRn blockade means using a medicine that prevents FcRn from rescuing IgG. When IgG can no longer bind effectively to FcRn, more IgG is directed towards lysosomal degradation. This leads to a reduction in total circulating IgG, including pathogenic IgG autoantibodies.

This approach is different from many traditional immunosuppressive treatments. FcRn blockade does not aim to shut down broad immune-cell activity. It does not directly deplete B cells, T cells or plasma cells. Instead, it reduces the circulating level of IgG antibodies that have already been produced. This is why the effect can be relatively rapid and reversible.

Why IgG autoantibodies matter in autoimmune disease

Autoimmune diseases are not all the same. Some are mainly driven by T-cell inflammation, some by cytokines, some by immune-complex formation, and some by disease-causing autoantibodies. FcRn blockade is most relevant where IgG autoantibodies have a clear pathogenic role.

In IgG-mediated autoimmune disease, autoantibodies may bind to cell-surface receptors, structural proteins, platelets, red blood cells, skin adhesion proteins or other self-antigens. The clinical effect depends on the target. In some conditions the antibody blocks normal receptor function. In others it activates complement, marks cells for clearance, or causes inflammation at a tissue surface.

The important principle is that lowering pathogenic IgG may reduce the autoimmune signal while leaving other immune mechanisms more intact than with broad immunosuppression. Immunoglobulin A, immunoglobulin M and many cellular immune functions are not directly targeted by FcRn blockade, although clinical monitoring remains essential because IgG is an important part of infection defence.

Examples of FcRn-targeting medicines

Several FcRn-targeting treatments have been developed or are under clinical investigation. These include efgartigimod alfa, rozanolixizumab, nipocalimab and batoclimab. They differ in molecular structure, route of administration, dosing schedule, regulatory status and clinical development programme.

Efgartigimod alfa is an engineered human IgG1 Fc fragment designed to bind FcRn and reduce IgG recycling. Rozanolixizumab is a humanised monoclonal antibody directed against FcRn. Nipocalimab and batoclimab are FcRn-blocking monoclonal antibodies being studied across several IgG-mediated autoimmune conditions. Availability in the UK and Europe depends on the licensed indication, local commissioning, specialist assessment and individual patient suitability.

Important clinical point

FcRn blockade is not a general treatment for all autoimmune symptoms. It is a specialist treatment strategy considered when the disease mechanism, antibody profile, clinical severity, previous treatment response and safety profile support an IgG-lowering approach.

How quickly does FcRn blockade work?

Because FcRn blockade increases the breakdown of circulating IgG, it may reduce IgG levels more quickly than treatments that depend on slowly altering antibody production. The timing of clinical improvement varies between conditions and between patients. A fall in antibody level does not always translate immediately into symptom improvement because tissue inflammation, complement activation, organ damage or downstream immune pathways may take longer to settle.

The effect is also reversible. When treatment is stopped, FcRn function gradually resumes and IgG levels may recover over time. This reversibility can be clinically useful, but it also means that repeated or maintenance treatment may be required in some chronic relapsing conditions.

Is FcRn blockade immunosuppression?

FcRn blockade is best understood as targeted immunomodulation rather than broad immune suppression. It lowers IgG by increasing IgG catabolism. It does not directly suppress bone marrow function, does not directly deplete lymphocytes and does not act like high-dose corticosteroids or conventional cytotoxic immunosuppressants.

However, IgG is important for immune protection. Patients being considered for FcRn blockade require specialist assessment of infection history, vaccination status, current medicines, immunoglobulin levels, pregnancy status where relevant, co-existing medical conditions and the need for monitoring during treatment.

Safety considerations and monitoring

The safety profile depends on the specific medicine, the dose, the route of administration and the patient’s underlying condition. Reported adverse effects vary between products but may include headache, injection-site reactions, upper respiratory tract infections, nausea, diarrhoea, fever, rash or infusion-related symptoms. Because FcRn also participates in albumin homeostasis, some FcRn-targeting approaches may require attention to serum albumin, although the extent of albumin change differs between molecules.

Before treatment, clinicians may check full blood count, liver and kidney function, immunoglobulin levels, infection risk, vaccination history and disease-specific autoantibody markers. During treatment, monitoring may include symptom scores, clinical examination, infection surveillance, IgG levels where appropriate, treatment tolerance and review of concomitant medicines.

Patients should inform their clinician if they develop recurrent infections, persistent fever, new unexplained symptoms, severe headache, allergic-type symptoms, pregnancy, planned surgery, or if they are due to receive vaccines. Live vaccines and timing of vaccination should be discussed with the treating specialist.

How FcRn blockade differs from other antibody-lowering treatments

Plasma exchange can remove antibodies rapidly from the circulation, but it is a procedure-based treatment and may require vascular access. Intravenous immunoglobulin can modulate immune function through several mechanisms, including Fc receptor effects, complement modulation and anti-inflammatory signalling. B-cell targeted treatments reduce the formation of new antibody-producing immune responses but may take longer to affect established antibody levels and may have broader immune effects.

FcRn blockade occupies a different position. It is pharmacological rather than procedure-based, reduces IgG by accelerating its natural breakdown, and can be repeated according to the licensed product schedule and specialist treatment plan. It may be considered when the aim is to lower pathogenic IgG without using broad immune suppression, although it is not suitable for every patient or every autoimmune condition.

Who may benefit from specialist assessment?

A specialist immunology or relevant organ-specific specialist assessment may be appropriate for patients with suspected antibody-mediated autoimmune disease, especially where standard treatments have not provided adequate disease control, where corticosteroid exposure is problematic, or where there is a documented pathogenic IgG autoantibody associated with active disease.

Assessment should include confirmation of diagnosis, review of previous investigations, antibody testing, disease activity measurement, treatment history, infection history and discussion of the balance between potential benefit and risk. FcRn blockade should not be started purely because an autoantibody is present; the antibody must be interpreted in the full clinical context.

Patient information

This page is for general medical education. FcRn-blocking medicines are prescription-only specialist treatments. They should only be considered after diagnosis, antibody testing and clinical review by an appropriately experienced clinician.

Summary

FcRn is a natural recycling receptor that protects IgG antibodies from degradation. This mechanism is useful for normal immune protection but may also prolong the survival of pathogenic IgG autoantibodies in antibody-mediated autoimmune disease. FcRn blockade interrupts this recycling pathway, increases IgG breakdown and can reduce circulating pathogenic IgG without directly suppressing the whole immune system.

This is an important development in modern immunology because it offers a targeted way to address IgG-driven disease mechanisms. Its role depends on the specific condition, the antibody involved, the licensed indication, treatment availability and the patient’s overall clinical situation.

References

  1. Gjølberg TT, Andersen JT, Sandlie I. Targeting the neonatal Fc receptor in autoimmune diseases: pipeline and progress. BioDrugs. 2025.
  2. Zhu L, et al. FcRn inhibitors: transformative advances and significant potential in autoimmune diseases. Front Immunol. 2025.
  3. Yang CW, et al. Evaluating the clinical impact of FcRn inhibition in IgG-mediated autoimmune disease. Autoimmun Rev. 2025.
  4. Seth NP, et al. Nipocalimab, an immunoselective FcRn blocker that lowers IgG, including pathogenic autoantibodies. Clin Pharmacol Ther. 2025.
  5. Nilforoushzadeh MA, et al. FcRn inhibitors in immune thrombocytopenia: a comprehensive review of therapeutic advances and clinical outcomes. Transfus Apher Sci. 2025.
  6. Yasuda M, et al. Opposing effects of efgartigimod and rozanolixizumab on serum albumin levels. Naunyn Schmiedebergs Arch Pharmacol. 2026.
  7. European Medicines Agency. Vyvgart: efgartigimod alfa. European public assessment report.
  8. European Medicines Agency. Rystiggo: rozanolixizumab. European public assessment report.

New report shows the benefits of immunotherapy for asthma

14th April 2018

Immunotherapy for asthma

New report shows the benefits of immunotherapy for asthma

A report from the Agency for Healthcare Research and Quality (AHRQ), published in March, revealed the benefits of using immunotherapy for asthma, specifically allergic asthma. The report is based on research into the benefits of both subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT).

You can use immunotherapy to treat allergic asthma. Allergic asthma is a reaction caused by exposure to an allergen. Common allergens include pollen, house dust mites, and animals. Allergens trigger an asthma attack which causes symptoms including wheezing, coughing, shortness of breath, and tightness in the chest. It’s a health issue that’s becoming increasingly common. In Europe, three people die per day as a result of asthma. It can especially be an issue in the winter.

Immunotherapy

Immunotherapy for asthma comes in the form of subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT). Both methods seek to reduce sensitivity to allergens that cause allergic asthma, therefore reducing the symptoms. To do so, the patient is repeatedly administered with one or multiple allergens to increase their tolerance to them. SCIT does this by injecting a solution containing the allergens under the skin. With SLIT, allergen exposure comes via an aqueous solution or tablet placed under the tongue.

The report states that SCIT and SLIT reduce the need for long-term control medication. Both treatments improve asthma-specific quality of life, decrease the use of quick-relief medications, decrease the use of systemic corticosteroids, and improve forced expiratory volume. SLIT showed further evidence of improving asthma symptoms in patients.

What does this mean?

These results are important for the health of people living with allergic asthma. Although many with asthma rely on long-term medications and corticosteroids, their use can have negative side effects. These may include coughs, voice changes, and oral thrush.

Some quick-relief medications used for allergic asthma can cause increased heart rates, headaches, high blood sugar, mood alterations, weight gain, and hypokalemia. By replacing these treatments with immunotherapy, the long and short-term health of people with allergic asthma could improve.

This may be why immunotherapy was also shown to improve people’s well-being. As well as experiencing reduced symptoms of allergic asthma, people were also less reliant on drugs to stay in control of their allergies. This means less time spent worrying about if you have enough medication, if your child has taken theirs to school, if teachers know how to use it, or remembering to take it. This makes for a more relaxed management of allergic asthma. This improves mood and reduces stress and anxiety which comes as a result of the condition.

The report did show a need for further research into the effectiveness of immunotherapy for the treatment of allergic asthma. There is little evidence to provide any comparative understanding of how effective immunotherapy is among different age groups, for different allergens, and in different settings. But with medical advancements in allergy treatments every day, the prognosis is looking good.

5.4 million people in the UK are currently undergoing treatment for asthma. If you think you should be one of them and would like to understand your symptoms further, book an appointment with one of our consultants. We use simple tests to determine what allergens may be causing your symptoms and provide the best ways to deal with them. Book an appointment today.

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