UK hay fever season now lasts up to two weeks longer, major review finds

Millions of people in the UK are enduring hay fever symptoms for up to two weeks longer than they did in the 1990s, according to a major review that links the trend to climate change. The report, published in Lancet Public Health and compiled by 65 scientists from around the world, concludes that climate change has "prolonged the pollen season" by extending the flowering period of some plants.

Examining three trees common in Europe — birch, alder and olive — the authors found that pollination began one to two weeks earlier between 2015 and 2024 compared with 1991 to 2000. "We are seeing a prolonged season – an earlier onset of pollination in both the north and south [of Europe]," said Professor Joacim Rocklov of the University of Heidelberg, one of the paper’s authors.

He said more research is needed to determine whether climate change is also increasing the amount of pollen in the air and making symptoms more severe. Early summer is typically peak pollen season, when counts rise sharply.

Warmer weather in the UK over the past two years has created ideal conditions for birch tree pollen — a major trigger — and warm, dry days help spread pollen through the air, a phenomenon often dubbed a "pollen bomb". Any extension of the season could affect millions, health charities say.

"While for some their symptoms can be mild, for many their hay fever symptoms impact their quality of life," said Anne Biggs, deputy head of clinical services at Allergy UK. "It can mean missed days at work, poor sleep and, for some teenagers and young people, active hay fever symptoms can mean they drop an academic grade in their exams." Pollen can also trigger dangerous reactions in people with existing respiratory conditions.

"If people are allergic to pollen, it can inflame their airways and cause terrifying breathing conditions, which can lead to life-threatening asthma attacks and COPD flare-ups," said Dr Samantha Walker, director of research and innovation at Asthma and Lung UK.

There is no cure for hay fever, but medicines can help relieve symptoms. Allergy expert Professor Stephen Till of Guy’s and St Thomas’ Hospitals in London recommended a "cocktail approach", including non-drowsy, long-acting antihistamine tablets or drops. He said different medicines work in different ways and are safe for most people, advising sufferers to seek guidance from a pharmacy.

The authors of the review report earlier pollination across Europe and say the trend warrants closer study. If the season continues to lengthen, clinicians and patient groups warn the burden on people with allergies and respiratory disease is likely to grow, underscoring the need for better management and ongoing research into how changing climate patterns affect pollen levels.