Allergy Immunotherapy: Answering the Most Common Patient Questions

Allergen Immunotherapy (AIT) is the only treatment in allergy medicine that modifies the underlying cause of allergic disease rather than just managing its symptoms. Despite strong evidence for its effectiveness, many patients hesitate — partly from misconceptions, partly from uncertainty about what the process involves. I have answered the questions patients ask me most often in clinic.

What exactly is immunotherapy doing?

When you are allergic to something, your immune system has incorrectly learned to treat a harmless substance (a pollen, a dust mite protein) as a threat. Immunotherapy introduces very small, gradually increasing doses of the allergen in a controlled way. Over time, this re-educates the immune system — shifting the response from allergic (IgE-mediated, Th2) to tolerant. The result is reduced symptoms, reduced medication need, and — uniquely — long-lasting protection that continues even after you stop treatment.

Who is a candidate?

It is not suitable for patients with severe uncontrolled asthma, active autoimmune disease, or those taking beta-blocker medication (in most cases).

• Patients with allergic rhinitis (hay fever) who have year-round or poorly controlled symptoms despite medication
• Asthma patients whose disease is triggered or worsened by known allergen sensitisation — AIT can reduce asthma medication requirements
• Eczema (atopic dermatitis) patients with confirmed sensitisation to house dust mites
• Patients with confirmed allergy to insect venom (bee, wasp) — venom immunotherapy reduces the risk of future anaphylaxis dramatically
• Children from age 5 — earlier treatment may prevent new sensitivities developing and slow the 'atopic march'

Allergy shots vs sublingual drops — which is better?

Both routes are effective for most allergens. The choice depends on clinical factors and patient preference:

• SCIT (injections): slightly more evidence for efficacy; suited to venom allergy (drops not available for venom); requires clinic visits
• SLIT (sublingual drops or tablets): convenient — taken at home; no needles; preferred for children who are needle-averse; equally effective for dust mites and grass pollen
• Compliance is critically important for both. SLIT's convenience improves adherence for many patients

Is it painful?

Allergy injections use very fine needles — similar to an insulin pen — into the skin of the upper arm. Most patients describe it as a minor pinch at most. The 30-minute observation period that follows is the only genuine inconvenience for most. Sublingual drops are entirely pain-free.

How long does it take to notice a difference?

Many patients notice improvement in symptoms during the build-up phase (3–6 months into SCIT). For SLIT, meaningful symptom improvement is typically seen after the first full pollen or mite season — around 6–12 months. The full benefit develops over the 3-year treatment course. It is important to have realistic expectations and continue treatment even during good periods.

Can I stop my other allergy medications during immunotherapy?

Not initially. During the build-up phase, your regular medications continue as usual. As immunotherapy takes effect — typically 6–18 months in — many patients find they need progressively less antihistamine or nasal spray to control symptoms. Your dose reduction should always be guided by your specialist; do not stop preventer medications abruptly.

What happens after the 3-year course?

Studies show that the benefits of a complete 3-year course of immunotherapy persist for at least 3–7 years after stopping treatment. Some patients achieve what appears to be permanent tolerance. A minority may need a further maintenance course if symptoms return — but this is far less common when the initial course is completed fully.

If you have been managing allergy symptoms with medications for years without achieving good control, or if you want to address the root cause rather than mask symptoms indefinitely, immunotherapy is worth discussing at your next consultation.