How Long Immunotherapy Takes to Work – What to Expect in Your First Year

If you’re considering allergy immunotherapy (also called desensitisation), it’s natural to wonder how quickly you’ll notice results. After all, when hay fever symptoms hit hard, we often want something that works straight away.

The important thing to know is that immunotherapy isn’t a quick fix. But when it’s started at the right time, it can make a real and lasting difference – even in your very first year.

Immunotherapy Is Not a Quick Relief Treatment

Unlike antihistamines or nasal sprays, which can ease symptoms within hours or days, immunotherapy doesn’t work immediately. That’s because it’s not designed to just mask symptoms – it retrains your immune system over time to become less sensitive to the allergen (like grass or tree pollen).

As Professor Adam Fox, AllergyRhino Co-Founder explains:

“I always tell my patients that immunotherapy is not a quick fix. It’s not something that’s useful if you’re suffering at the time from severe symptoms – that’s where medication will be much more useful.”

This means that if you’re already deep into a hay fever flare-up, medication will always be the more useful option for rapid relief.

Timing Is Everything

Immunotherapy is a preventative treatment. To get the benefit in your first hay fever season, you need to start a few months before your main allergy symptoms usually begin.

“Immunotherapy really is a preventative treatment that needs to be started a few months before your hay fever kicks in. As long as you start before the season begins, you should expect to see a significant improvement – perhaps a 30 to 40% improvement – in that first year.”

• For grass pollen allergy: start by late January or early February, to build tolerance before April–June, when grass pollen peaks.

• For tree pollen allergy: treatment ideally begins in the autumn, before the early-spring pollen season arrives.

“For patients with grass pollen symptoms that start in April, treatment really needs to start by the end of January at the latest. For tree pollen, ideally by October or November.”

What to Expect in Your First Year

If you begin immunotherapy on time, you can usually expect around a 30–40% reduction in symptoms during your first season. That might sound modest, but in reality, it can be life-changing.

For someone who usually spends weeks with itchy eyes, blocked sinuses, poor sleep, and constant sneezing, a 30–40% improvement can mean:

• Better concentration at school or work

• Improved sleep quality

• Fewer days disrupted by allergies

• Less reliance on antihistamines and nasal sprays

Patients often describe the difference as finally being able to “get on with their lives.” One AllergyRhino patient put it this way:

“I just be relieved. Like, I feel like I can be a bit more normal. Not worry about, like, bringing enough tissues everywhere.”

When Hay Fever Is Severe

If your symptoms are particularly bad, immunotherapy alone may not be enough in year one. That’s why many patients see the best results from a combination approach:

• Starting the right medication before the season (antihistamines and nasal sprays, used consistently)

• Adding immunotherapy to reduce overall sensitivity

“If your hay fever is very severe, then a combination of being on the right medication together with being desensitised will make a very, very big difference to how your hay fever season goes.”

The Long Game: Why It’s Worth It

Immunotherapy requires patience – it’s taken daily for at least three years – but unlike standard medication, its benefits continue long after treatment finishes.

“At the end of a three-year course, the effect that you get will last for many years afterwards. That’s in stark contrast to regular hay fever medications that only work when you take them.”

For many people, that means years of lighter symptoms or even freedom from hay fever altogether.

One of our customers on dust-mite immunotherapy, said it best:

“It’s given me a lot of hope. I just want to go to work or be outdoors without constantly worrying about feeling horrible.”

Key Takeaway

Don’t expect overnight results – but by starting immunotherapy a few months before your allergy season, you can look forward to a noticeable improvement in year one, and even greater benefits over time.

Immunotherapy doesn’t just make hay fever more bearable. It can change your relationship with your allergies – for good.