Immunotherapy and hay fever

For many people, the arrival of spring heralds hefty doses of antihistamines, nasal sprays and eye drops to relieve hay fever symptoms.

Allergic reactions to pollen typically include a runny nose, itchy eyes and persistent sneezing, but for some, the symptoms can be debilitating and life-altering, and common remedies may have little effect. 

Hope is at hand, however, in the form of immunotherapy. The most acute hay fever sufferers are sometimes referred for the treatment, and now new research "highlighting its effectiveness" may lead to immunotherapy becoming "more widely available on the NHS", said the Daily Mail.

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What is immunotherapy?

In essence, immunotherapy aims to "induce a shift in the immune response" of a patient, said Samuel J. White and Philippe B. Wilson from Nottingham Trent University on The Conversation. So instead of producing histamines that cause the classic symptoms of hay fever, the body produces "antibodies that can neutralise the allergen" and prevent an allergic reaction from occurring.

The process of immunotherapy trains the body to "avoid its overreaction" to a specific allergen, said Healthnews, and instead build a "tolerance" to it.

That usually begins with a three- to six-month "build-up phase", during which small doses of the allergen are administered to induce T-regulatory cells, which prevent the release of histamines. Doses are then gradually increased until the target dose is reached, at which point the "maintenance phase" begins, lasting for three to five years or longer.

Immunotherapy can be administered in two ways: under the skin via an injection (subcutaneous), or via the newer method of under the tongue using liquid drops or tablets (sublingual).

How effective is it?

Both types of immunotherapy treatment have demonstrated effectiveness in research. Subcutaneous has been used for much longer and so has a greater history of evidence showing it works. While it is considered safe, uncommon side effects include allergic reactions and a rash around the injection site.

The oral method has be shown to be "marginally less effective" than injections, said White and Wilson, but is considered "slightly safer".

The treatment usually begins a few months before the pollen season starts. Research has shown that treatment over three to five years can have longer-lasting benefits and is "effective in reducing symptoms and use of medications such as antihistamines". Sublingual treatment has been shown to be "particularly effective for hay fever caused by grass or tree pollens".

How do people access the treatment?

Despite the evidence of the effectiveness of immunotherapy in treating hay fever, it is currently "not available to the majority of people" with the condition in Britain, said The Sun.

Only 2,839 people in the UK out of the estimated 13 million hay fever sufferers are receiving three years of immunotherapy treatment, according to research by the British Society for Allergy & Clinical Immunology. The use of immunotherapy in the UK "severely lags behind the US and Europe", consultant paediatrician Dr Tom Dawson told the Daily Mail, despite the UK being "at the forefront of allergy research".

Most people need to demonstrate severe hay fever symptoms that can't be relieved with standard treatments before a GP may refer them for immunotherapy.

The treatment costs around £2,000 a year per patient, but supporters argue that in the long term, immunotherapy could save the NHS money, by resulting in fewer people succumbing to more severe conditions such as seasonal asthma.

Despite evidence of its efficacy, not all patients will experience a complete relief of symptoms through immunotherapy, and it "may not be a suitable option for everyone", said White and Wilson. It also requires a long-term commitment to regular treatment and can often take "several months or even years to see the full benefits". For many people, though, immunotherapy could prove a "valuable tool" in easing their hay fever symptoms.