Key takeaways
- Skin-prick testing and suitability assessment are both offered by KKH’s children’s allergy service. A positive test alone does not establish which allergen is causing the symptoms. KKH
- After an injection, ASCIA advises staying at the clinic for at least 30 minutes and avoiding exercise for at least 3 hours. Sublingual treatment usually continues daily at home. ASCIA
- Expect a course of at least 3 years. For sublingual tablets, ASCIA says to call the doctor after a gap longer than 7 days. Either route can cause a serious reaction, so follow the emergency plan. ASCIA
Allergy immunotherapy: injections, tablets and treatment commitment
Allergy immunotherapy repeatedly exposes the immune system to a specific allergen under medical supervision. Injections and under-the-tongue products use different schedules and precautions, but both require a confirmed clinically relevant allergy and sustained adherence. They are not quick substitutes for antihistamines, and an anti-allergy biologic such as omalizumab is a different treatment rather than another delivery form of immunotherapy.
What is allergy immunotherapy trying to change?
Immunotherapy aims to change the immune response to a specific allergen over time. Usual allergic-rhinitis medicines reduce symptoms or inflammation during exposure. Allergen immunotherapy instead gives controlled, repeated exposure to an allergen with the aim of changing the immune response over time. It may be considered when a specific trigger such as house-dust mite or pollen is clearly linked to significant symptoms and ordinary measures have not provided acceptable control or are difficult to sustain.
A skin-prick or specific-IgE result shows sensitisation. The specialist still needs to establish whether that allergen causes the symptoms. That means looking at when nasal or eye symptoms occur, exposure at home and work, asthma control, previous reactions and current treatment. The Australasian Society of Clinical Immunology and Allergy (ASCIA) describes immunotherapy as specialist treatment selected for the allergens causing the person’s problem, not a general treatment for every positive result.
How do injections and under-the-tongue treatment differ?
Injections involve repeated supervised visits; sublingual treatment usually continues at home after supervised initiation.
| Question | Subcutaneous immunotherapy (SCIT) | Sublingual immunotherapy (SLIT) |
|---|---|---|
| How is the allergen given? | An injection under the skin, with a build-up phase followed by maintenance treatment | A tablet or liquid held under the tongue, usually on a regular home schedule after supervised initiation |
| Where is it given? | In a medical setting equipped to recognise and treat systemic reactions | Product- and jurisdiction-dependent; the first dose of licensed tablets is commonly supervised, with later doses at home |
| Common local effects | Redness, itch or swelling around the injection site | Mouth or throat itch, irritation or swelling, especially early in treatment |
| Main practical burden | Repeated clinic visits and an observation period after injections | Remembering consistent home treatment and following the exact product instructions |
| Serious risk | Systemic allergic reaction, including anaphylaxis | Less common than local mouth symptoms, but severe allergic reactions can still occur |
ASCIA cautions that different brands and preparations, including aqueous and alum-adsorbed extracts, cannot be interchanged. Its examples concern Australian and New Zealand products. For Singapore, the clinic must confirm the available product, age limits and suitability given asthma, other medicines, pregnancy and the ability to follow the schedule. ASCIA The AAAAI allergy-tablet guide notes that licensed tablet instructions are allergen-specific; a dust-mite tablet cannot be assumed to cover another trigger.
Singapore allergy services assess and supervise immunotherapy rather than treating it as a retail allergy product. For example, KK Women’s and Children’s Hospital lists allergen testing, suitability assessment, protocol supervision and management of reactions within its allergy service. Availability and exact instructions should therefore be confirmed with the treating service rather than inferred from an overseas product page.
Why does treatment take so long?
A course usually takes at least 3 years, according to ASCIA, because the treatment relies on sustained exposure. Its patient guide describes injections usually building up over 3 to 6 months, followed by monthly maintenance visits. Sublingual treatment is usually daily. Those schedules describe the commitment; the clinic must provide the instructions for the actual product. ASCIA
Missed visits or frequent missed home treatment interrupt the course and may change the restart instructions. ASCIA tells tablet users to contact their doctor after a gap longer than 7 days, and to seek advice about interruptions for dental procedures, mouth ulcers or an asthma flare. Never add extra treatment to catch up.
Early symptom improvement is not proof that the course is complete, and lack of immediate change is not a reason to increase exposure independently. Reviews consider symptom burden, rescue-medicine use, reactions, adherence and whether the original allergen remains the right target. A person still needs an ordinary plan for breakthrough rhinitis or asthma symptoms while immunotherapy is underway; see allergic rhinitis medicines and the allergy-relief category.
Is omalizumab another type of allergy immunotherapy?
No. Allergen immunotherapy administers a selected allergen; omalizumab targets free IgE. Omalizumab is a biologic medicine that binds free IgE and is used for particular approved conditions and patient groups. It does not identify or deliver the causal allergen, and it should not be presented as a routine companion that makes immunotherapy universally safer or more effective.
Specialists sometimes consider both treatments in complex cases. The decision about omalizumab requires its own assessment of benefit and risk; routine enhancement of immunotherapy should not be assumed.
Which reactions need urgent help?
Widespread hives, tongue or throat swelling, breathing difficulty, wheeze, faintness, collapse or rapidly worsening symptoms need emergency care. They can indicate anaphylaxis. Local injection-site redness and temporary mouth itch with sublingual treatment can also occur; the clinic should explain what to record and when to call. ASCIA describes rare digestive-tract allergic effects with sublingual products, including difficulty swallowing or reflux, which also require immediate medical contact. ASCIA
Tell the clinic about symptoms after the previous injection, including itchy eyes, nose or throat, increased wheeze and feeling faint or light-headed. ASCIA advises delaying treatment during an asthma flare until control returns; illness or fever may also warrant a delay. It advises avoiding exercise for at least 3 hours after an injection. Keep the observation appointment, and never change the interval or restart after a significant reaction without the treating service’s instructions. ASCIA
What changes the answer?
The trigger, asthma control, other medicines and ability to follow the programme determine suitability.
- The allergen and evidence of exposure. The available product must match a trigger that actually explains the symptoms.
- Asthma control. Poorly controlled asthma increases the danger of a systemic reaction. Current wheeze, recent attacks or reduced lung function may alter whether treatment proceeds that day or at all.
- Age and product licence. Age ranges differ between products and countries; overseas approval cannot establish Singapore suitability.
- Pregnancy or pregnancy planning. Immunotherapy is generally not newly started during pregnancy, while continuation decisions require the treating specialist.
- Other conditions and medicines. Cardiovascular disease, previous anaphylaxis and medicines that complicate treatment of a severe reaction require discussion. ASCIA names beta blockers such as metoprolol and propranolol, and asks patients to disclose glaucoma eye drops as well as heart or blood-pressure tablets. Bring the names for review; do not stop prescribed treatment independently. ASCIA
- Ability to follow the programme. Clinic access, travel, daily routines and understanding the emergency plan influence whether a route is realistic.
What should you ask at the assessment?
Ask which allergen explains the symptoms, how the proposed treatment is given and what to do after a reaction or missed treatment. Bring the symptom timeline, previous test results, inhalers and allergy medicines, details of reactions, and a complete medicine list. Ask which allergen is being targeted, what evidence links it to symptoms, which product and route are proposed, where doses are taken, what happens after a missed dose, which reactions require contact or emergency help, and how benefit will be reviewed.
The allergic-rhinitis condition page can help organise the diagnosis and ingredient names. It cannot determine whether a particular allergen extract is appropriate for an individual.
Sources
- Australasian Society of Clinical Immunology and Allergy: Allergen immunotherapy.
- American Academy of Allergy, Asthma & Immunology: What you need to know about allergy tablets.
- American Academy of Allergy, Asthma & Immunology: Hay fever and rhinitis.
- HealthHub Singapore / KKH: Allergy services.
