Allergen Immunotherapy (SCIT / SLIT)

Allergen immunotherapy — allergy vaccines — gradually retrains the immune system to tolerate a trigger such as grass pollen, dust mite or insect venom. It is given as an injection under the skin (SCIT) or as drops or a tablet under the tongue (SLIT), as a course lasting about three years. At Allergy Asthma Foundation it is carried out by an experienced team using current equipment and protocols, with clear information given before, during and after so that you know what to expect at every stage.

This page explains why the procedure is done, how to prepare, what happens on the day, and what recovery and follow-up involve. Your own consultant will go through the details that apply to your situation and answer any questions before you agree to go ahead.

Why it is done

Allergen immunotherapy is usually recommended for one or more of the following reasons:

• Hay fever or allergic asthma that is not controlled by avoidance and medicines
• A wish to reduce long-term reliance on antihistamines and steroid sprays
• Confirmed bee or wasp venom allergy with a risk of severe reactions
• A single clear trigger identified on testing that matches the symptoms
• Symptoms severe enough to affect sleep, school or work

It is only offered when the expected benefit clearly outweighs the risks, and the decision is always made together with you. If a simpler test or treatment would answer the question or relieve the problem, that is tried first.

How to prepare

• Bring your current medicines, your adrenaline auto-injector if you have one, and any record of previous doses or reactions.
• Take your usual asthma preventer and other regular medicines unless told otherwise.
• Do not have the treatment if you are unwell with a fever or an asthma flare on the day — call to rearrange.
• Avoid heavy exercise, a hot bath or alcohol for a few hours before and after.
• Plan to stay in the department for a period of monitoring after each dose.

What happens on the day

1. Treatment starts with a build-up phase of small, increasing doses given in the clinic.
2. Once the maintenance dose is reached, injections are spaced out to every few weeks, ordrops/tablets are taken daily at home.
3. Before each clinic dose your symptoms, peak flow and any reaction to the last dose arechecked.
4. You wait in the department for a period of observation after each injection.
5. Progress is reviewed regularly and the course continues for about three years.

After the procedure

Local itching or swelling at the injection site, or mild mouth itching with the under-the-tongue form, is common in the first weeks and settles. Avoid vigorous exercise, hot baths and alcohol for a few hours around each dose.

You will be given written instructions covering activity, wound or puncture-site care where relevant, which medicines to restart and when, and the warning signs that mean you should contact us or attend the emergency department. A follow-up appointment or a phone review is arranged before you leave.

Benefits and risks

The main benefit is a clear answer or effective treatment that changes what happens next — a firm diagnosis, a blocked passage reopened, symptoms brought under control, or a condition safely monitored over time. For most people the procedure is straightforward and complications are uncommon.

No procedure is entirely without risk. The ones to be aware of for this treatment include:

• Local swelling and itching at the injection site
• Mouth or throat itching and stomach upset with the sublingual form
• Uncommonly, a wider allergic reaction — the reason clinic doses are observed
• Rarely, anaphylaxis, which the clinic is fully equipped to treat

The team is trained and equipped to recognise and manage these, and the consent discussion covers how likely each is in your case and what is done to reduce it.

Results and follow-up

There is no test result; the measure of success is fewer and milder symptoms and less need for relief medicines, which many people notice within the first year and which can last for years after the course ends. Your consultant explains what the result means in the context of your symptoms and examination, and sets out the next step — reassurance and discharge, a change of treatment, a further test, or a planned review. With your consent a summary is sent to your family doctor so that everyone caring for you is working from the same plan.

Questions patients ask

Do I need a referral?

You can book a consultation directly to discuss whether allergen immunotherapy is right for you. The procedure itself is arranged by the consultant after that discussion, once you have had time to consider it.

Will it hurt?

Discomfort is kept to a minimum with local anaesthetic, sedation or pain relief as appropriate to the procedure. The team will tell you exactly what you are likely to feel and will stop or pause if you need them to.

How long will I be at the hospital?

Most people are in and out within a few hours; where an overnight stay or a longer recovery is expected, that is explained clearly when the procedure is booked so you can plan around it.

To arrange allergen immunotherapy at your nearest AAF centre, book a consultation online or request a callback. Please bring a list of your current medicines and any previous test results or discharge summaries.