SOS Allergo · I understand & manage
Allergen immunotherapy (AIT)
Understand your desensitisation, follow it correctly and know when to seek advice
This sheet mainly concerns AIT for respiratory allergies, such as pollen and house dust mite allergies. Venom immunotherapy and food immunotherapy have specific indications and procedures.
In this sheet
3 essential points
A positive test is not enough
AIT is offered when an allergen is genuinely linked to your symptoms. An isolated positive skin prick test or IgE result is not treated with desensitisation.
It acts on the allergic disease
Unlike treatments that mainly relieve symptoms, AIT aims to gradually modify the immune response to the allergen.
Regular treatment matters
When effective, respiratory AIT usually continues for several years. Irregular treatment may reduce the expected benefit.
Zen Minute · Demonstration
The Zen Minute
A calm moment with Yumi
Settle in calmly with Yumi.
Start when you are ready. Progress will follow the configured time only.
Follow the instructions you were given for your treatment.
Two-minute demonstration. The actual duration must be provided by a validated AIT pathway and medical configuration.
Understanding the principle
Why may AIT be offered?
It may be considered when allergic rhinitis or rhinoconjunctivitis remains troublesome despite appropriate management, when exposure is difficult to avoid or when the patient wants to reduce symptoms and treatment use in the long term. The allergen must be clinically relevant and the selected product must have evidence appropriate to the indication.
SLIT or SCIT: what is the difference?
- Route
- Under the tongue
- How it is administered
- Sublingual immunotherapy (SLIT): the allergen is administered under the tongue as a tablet or sublingual preparation, depending on the product. Much of the treatment continues at home according to the prescription.
- Route
- By injection
- How it is administered
- Subcutaneous immunotherapy (SCIT): the allergen is administered by injection in a medical setting, according to a precise schedule and with monitoring after the injection.
| Route | How it is administered |
|---|---|
| Under the tongue | Sublingual immunotherapy (SLIT): the allergen is administered under the tongue as a tablet or sublingual preparation, depending on the product. Much of the treatment continues at home according to the prescription. |
| By injection | Subcutaneous immunotherapy (SCIT): the allergen is administered by injection in a medical setting, according to a precise schedule and with monitoring after the injection. |
No route is always better. The choice depends on the allergen, available product, age, medical context, preferences and ability to follow treatment regularly.
Benefits and duration
What benefits can be expected?
- reduce symptoms;
- reduce the need for symptom-relieving treatments;
- improve quality of life;
- for some patients, provide a benefit that persists after treatment ends.
AIT does not promise a ‘cure’. Its benefit varies with the allergen, product and patient profile.
How long does treatment last?
To obtain lasting benefit for respiratory allergies, guidelines generally recommend a minimum of about 3 years when treatment is effective. Depending on the product, allergen and situation, treatment often lasts around 3 to 5 years. The decision remains individual.
How do we know whether it is working?
Assessment mainly considers symptoms, treatments still needed, quality of life, better tolerated seasons or exposures and, where relevant, asthma control. The aim is not to make a skin prick test negative.
‘I cannot see a difference yet’
Benefit is not always immediate. Do not stop by yourself after a few weeks or months: review progress with your allergist. Conversely, treatment that remains ineffective should be reassessed rather than continued automatically.
Reactions and safety
Reactions with sublingual AIT
At the start of SLIT, itching or tingling in the mouth, mild throat irritation or minor local swelling may occur. These local reactions are often more noticeable at first and then decrease.
When should I seek advice promptly?
Breathing difficulty, marked swelling, feeling faint or a generalised reaction are not simple local reactions: follow the plan provided by the team and seek appropriate medical help.
What about injections?
Redness or local swelling may occur at the injection site. Systemic reactions are uncommon but possible, which is why SCIT is administered in a medical setting with the monitoring required by the centre.
Asthma: a major safety consideration
Practical questions during treatment
I missed a dose: should I double it tomorrow?
No. What to do depends on the product and the length of the interruption. Do not double a dose by yourself; use the leaflet and the plan provided for your treatment, or ask the team for advice.
Mouth ulcer, dental care or infection: should treatment be paused?
Some oral or infectious conditions may require certain sublingual treatments to be paused temporarily, but the rules differ by product. Do not create your own interruption rule.
Difficulty swallowing during SLIT: why should I mention it?
Persistent difficulty swallowing, food sticking or other unusual oesophageal symptoms should be reported to the doctor. Eosinophilic oesophagitis is a specific consideration with SLIT.
Pregnancy
AIT is not usually started during pregnancy. A well-tolerated course already under way may sometimes continue after discussion with the team. Do not stop or change it automatically without advice.
Should I continue antihistamines, nasal sprays or asthma treatment?
Yes, if they remain prescribed. AIT and symptom-relieving treatment are complementary. Any reduction depends on clinical control, not simply on having started desensitisation.
Sensitised to several allergens: should all of them be treated?
No. In a person sensitised to several allergens, AIT may target a limited number that genuinely cause symptoms. More positive tests do not mean more courses of desensitisation.
Do not confuse the different forms of immunotherapy
- Situation
- Respiratory allergies: pollen, house dust mites and other selected situations — the main subject of this sheet.
- How they differ
- Hymenoptera venom: specific indications, organisation and duration — see the Venom sheet.
- Situation
- Food allergies: oral immunotherapy uses specialist protocols and is not the same as respiratory SLIT.
- How they differ
- Pollen-food allergy syndrome (PFAS): pollen AIT is not started solely to treat cross-reactive food symptoms.
| Situation | How they differ |
|---|---|
| Respiratory allergies: pollen, house dust mites and other selected situations — the main subject of this sheet. | Hymenoptera venom: specific indications, organisation and duration — see the Venom sheet. |
| Food allergies: oral immunotherapy uses specialist protocols and is not the same as respiratory SLIT. | Pollen-food allergy syndrome (PFAS): pollen AIT is not started solely to treat cross-reactive food symptoms. |
Common misconceptions
- Misconception
- ‘My skin prick test is positive: I need desensitisation.’
- SOS Allergo guidance
- No. The allergy must be clinically relevant.
- Misconception
- ‘Desensitisation replaces my nasal sprays from day one.’
- SOS Allergo guidance
- No. Symptom-relieving treatments may still be needed.
- Misconception
- ‘If my test stays positive, AIT has failed.’
- SOS Allergo guidance
- No. Effectiveness is assessed primarily through symptoms and medicine use.
- Misconception
- ‘The more allergens in the treatment, the better.’
- SOS Allergo guidance
- No. Treatment targets the allergens genuinely responsible.
- Misconception
- ‘I missed yesterday’s dose: I should double it today.’
- SOS Allergo guidance
- No.
- Misconception
- ‘Pollen desensitisation treats PFAS.’
- SOS Allergo guidance
- PFAS alone is not a sufficient indication.
| Misconception | SOS Allergo guidance |
|---|---|
| ‘My skin prick test is positive: I need desensitisation.’ | No. The allergy must be clinically relevant. |
| ‘Desensitisation replaces my nasal sprays from day one.’ | No. Symptom-relieving treatments may still be needed. |
| ‘If my test stays positive, AIT has failed.’ | No. Effectiveness is assessed primarily through symptoms and medicine use. |
| ‘The more allergens in the treatment, the better.’ | No. Treatment targets the allergens genuinely responsible. |
| ‘I missed yesterday’s dose: I should double it today.’ | No. |
| ‘Pollen desensitisation treats PFAS.’ | PFAS alone is not a sufficient indication. |
Information that helps during AIT follow-up
- allergen treated
- product name
- start date
- method of administration
- missed doses or interruptions
- local or general reactions
- changes in symptoms
- treatments still needed
- asthma control
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References and resources
- Roberts G, Pfaar O, Akdis CA, et al. EAACI Guidelines on Allergen Immunotherapy: Allergic rhinoconjunctivitis. Allergy. 2018;73(4):765-798. doi:10.1111/all.13317. PMID: 28940458.
- Gurgel RK, Baroody FM, Damask CC, et al. Clinical Practice Guideline: Immunotherapy for Inhalant Allergy. Otolaryngol Head Neck Surg. 2024;170(Suppl 1):S1-S42. doi:10.1002/ohn.648. PMID: 38408152.
- Société Française d'Allergologie. Fiches pratiques de prescription et de suivi de l'immunothérapie allergénique (ITA), ressources SFA, 2025-2026.
- Halken S, Larenas-Linnemann D, Roberts G, et al. EAACI guidelines on allergen immunotherapy: Prevention of allergy. Pediatr Allergy Immunol. 2017;28(8):728-745. PMID: 28902467.
- Pajno GB, Fernandez-Rivas M, Arasi S, et al. EAACI Guidelines on allergen immunotherapy: IgE-mediated food allergy. Allergy. 2018;73(4):799-815. doi:10.1111/all.13319. PMID: 29205393.
General information: this sheet does not replace the instructions specific to the prescribed product or your allergist’s personalised plan.
Scientific review: September 2026 · sosallergo.fr