What Is Immunotherapy for Hayfever? A Complete Guide to Allergy Desensitisation Treatments

If you're struggling with hayfever year after year—and nothing seems to work—immunotherapy treatment could be the long-term solution you've been looking for.

In this guide, we explain what immunotherapy is, how it works, and how you can access private allergy desensitisation treatment through our clinics. Whether you're new to the concept or just weighing up your options, this post will give you a clear picture of what to expect.

What Is Immunotherapy?

Immunotherapy—or allergen immunotherapy—is a long-term treatment that helps reduce your body’s allergic response to a specific allergen, like pollen, dust mites, or insect venom. Instead of just treating the symptoms like antihistamines do, it tackles the root cause of the allergy.

The idea is to train your immune system to stop overreacting to harmless substances (like grass or tree pollen) by slowly introducing the allergen in small, controlled doses over time. This process is often referred to as desensitisation.

Think of it as a vaccine for allergies. This treatment is available at our clinics as part of our Private Allergy Testing and Treatment services.

How Does Immunotherapy for Hayfever Work?

Immunotherapy introduces small amounts of the allergen to your body over time to build up tolerance. It’s available in two forms:

1. Immunotherapy Injections for Allergies (SCIT)

This involves regular injections—usually into your upper arm—containing small amounts of the allergen. These allergy immunotherapy injections are given every 1–2 weeks at first (the ‘updosing’ phase), then less frequently once a maintenance dose is reached.

Because they can cause reactions, you’ll need to stay at the clinic for 30 minutes after each jab for monitoring.

2. Sublingual Immunotherapy (SLIT)

This is a needle-free option that uses drops or tablets placed under the tongue. It’s typically taken daily at home and has fewer risks of serious reactions than injections. This type of sublingual immunotherapy is especially popular for children or anyone who hates needles! A common example in the UK is the Grazax® tablet, which is used for grass pollen allergy. 

Both treatments are provided by our Private GPs and are administered under the care of trained specialists.

What Can Immunotherapy Treat?

Allergen immunotherapy is effective for:

• Hayfever (caused by grass, tree, or weed pollen)
• House dust mite allergy
• Bee and wasp venom allergies

It may also help with some pet or mould allergies, although the evidence is less strong, and products may not be officially approved.

What Is the Success Rate of Immunotherapy?

Great question. If you’re wondering what is the success rate of immunotherapy, the numbers are promising:

• Around 70–90% of patients report significant symptom relief.
• Clinical trials show an average 30% improvement in Year 1, 50% in Year 2, and 70% in Year 3.
• Many people continue to benefit years after treatment ends.

It also helps reduce the need for medication and can prevent allergies from developing into asthma.

What to Expect From Immunotherapy Treatment

Treatment Duration

• Takes at least 3 years for full benefits
• Continued relief can last several years beyond that

Time Commitment

• Injections require regular clinic visits
• SLIT tablets/drops are taken daily at home

Medications

You may still need antihistamines and nasal sprays during high pollen days, but many find they can reduce or even stop them over time.

Are There Any Side Effects or Risks?

Yes, like any treatment, there are potential side effects—most are mild:

Common Side Effects:

• Local reactions at the injection site (redness, swelling)
• Mild allergic symptoms (sneezing, itchy mouth, watery eyes)
• Tiredness or headache

Rare but Serious:

• Anaphylaxis (a severe allergic reaction) is extremely rare, affecting fewer than 1 in 1,000 injection patients.

Before starting treatment, we’ll ensure your asthma (if applicable) is well controlled and review any medications like beta blockers that may need adjusting.

Is Immunotherapy Right for You?

Immunotherapy for hayfever treatment is usually considered if:

• You have severe symptoms not controlled by medication
• You want a long-term solution rather than short-term relief
• You’re allergic to a specific, known allergen

It’s not suitable for everyone, especially those with multiple allergies or uncontrolled asthma—but if you’re a good candidate, it can be life-changing.

FAQs About Immunotherapy

How long does immunotherapy take to work?

You might start seeing improvements in the first year, but full benefits often take 3 years of consistent treatment.

Is sublingual immunotherapy as effective as injections?

Both are effective. Injections may offer slightly stronger symptom relief, but SLIT is more convenient and safer for home use.

Can children have immunotherapy?

Yes, immunotherapy for hayfever is safe for both adults and children, as long as they’re under specialist supervision.

Can I do immunotherapy during pollen season?

Yes! It’s possible to start even in the spring or summer. Studies show it’s just as safe and effective as starting in winter.

Is it available on the NHS?

Allergy immunotherapy injections may be available through specialist NHS allergy clinics, but sublingual options are often private and can be costly. Speak to our GP about referral options.

Final Thoughts

If hayfever is making your life miserable year after year, immunotherapy treatment could be your ticket to long-term relief. It takes time and commitment, but it’s one of the few treatments that addresses the cause, not just the symptoms.

Whether you choose immunotherapy injections or go for sublingual allergy immunotherapy, speak to our GP or an allergy specialist to find out if it’s the right path for you.