Every other hay fever treatment suppresses symptoms while you take it. Allergen immunotherapy — desensitisation — aims to change the underlying allergic response itself, so that pollen stops provoking the reaction.
It works by exposing you to controlled, gradually increasing amounts of the allergen until the immune system stops treating it as a threat.
The Two Forms
Sublingual immunotherapy
A tablet or drops placed under the tongue daily, taken at home after the first dose is given under supervision. This is the more common route for grass and tree pollen allergy in the UK.
Subcutaneous immunotherapy
Injections given in a specialist clinic, with an observation period afterwards because of the risk of systemic reactions. Less convenient, and used in particular circumstances.
Who It Is For
Immunotherapy is generally considered when:
- Symptoms are moderate to severe
- Standard treatments — antihistamines plus a steroid nasal spray, used correctly — have not given adequate control
- The specific allergen has been confirmed by testing
- Symptoms significantly affect quality of life, work or education
It is not a first step, and a specialist will want evidence that the simpler treatments genuinely failed rather than were used badly.
The Commitment
This is the part that decides it for most people. A full course runs for about three years. Sublingual treatment for pollen is usually started several months before the season begins and continued daily.
Stopping early substantially reduces the chance of lasting benefit. Three years of daily treatment for a seasonal problem is a real commitment, and it is better to decline it than to abandon it halfway.
What It Achieves
Where it works, benefit is meaningful and persists for years after the course finishes — the distinguishing feature against every other option. It can reduce the medication you need during the season and, in children, there is evidence it may reduce the risk of going on to develop asthma.
It is not a guaranteed cure. Some people get a large improvement, some a modest one.
Risks
Sublingual treatment commonly causes local reactions — itching or swelling in the mouth and throat, usually in the first weeks and usually settling. Systemic allergic reactions are rare but possible, which is why the first dose is supervised and why patients are counselled on what to do.
Subcutaneous immunotherapy carries a higher risk of systemic reactions, hence clinic administration and observation.
Access in the UK
Immunotherapy is available on the NHS through allergy and immunology services, but access varies considerably by area and referral criteria are strict. Private allergy clinics offer it, at a cost that reflects both the medicine and three years of specialist follow-up.
Either route starts the same way: a GP appointment and a discussion about referral. It is not something to arrange through an online pharmacy — it needs allergy testing, specialist assessment and supervised initiation.
Weighing It Up
Set the three-year commitment against the alternative, which for a severe sufferer is decades of seasonal medication. For someone whose hay fever genuinely disrupts several months of every year and who has already exhausted the standard treatments, that arithmetic often favours immunotherapy.
For someone whose symptoms are well controlled by a cheap antihistamine and a nasal spray, it does not.