An end to hay fever? The new wave of effective cures for seasonal allergies

By the 1980s, this became a recognised treatment. These "allergy shots" proved highly effective, easing the sneezing and suffering of thousands of patients. But there was a problem. "Injection immunotherapy has occasionally killed people," says Scadding, due to anaphylaxis – an allergic reaction to the shot itself.

These events are extremely rare, occurring in about one per 2-2.5 million injections, and today, thanks to a better understanding of risk factors and of proper administration, they are rarer still.

But when about 26 anaphylaxis-related deaths from subcutaneous immunotherapy were recorded in the UK from 1957 to 1986, the UK passed new regulations – including, at the time, that anyone who received an injection had to wait at the doctor's office for observation for two hours. (Now, it’s 30 minutes). Since injections have to be given regularly, often weekly, this requirement made subcutaneous immunotherapy onerous.

Interest increased in the oral alternative that Scadding had been pioneering in the 1980s. Sublingual therapy, as it is known, involves placing droplets of the allergen under the tongue, rather than being injected into the arm. There was initially some scepticism that it could work as well as the shots, which led to some pushback.

"Sublingual was regarded as a real 'fringe' thing which wasn't going to work," Scadding says. "So I stopped doing it for a while." But the trials suggested that it provided much lower risk of anaphylaxis than its subcutaneous counterpart, while still being highly effective. "There have been no fatalities. Serious adverse events are very rare," Scadding says. She notes local reactions, like temporary itching or swelling of the tongue, are more common.