Butterbur’s alleged hay fever-fighting properties have been eyed with scepticism by some scientists over the last few years, but the largest trial conducted to date suggests that an extract from the herb is as effective at alleviating symptoms as a common anti-histamine.

Hayfever, also known as seasonal or intermittent allergic rhinitis, is estimated to affect around 20 percent of people in Western countries - although the true figure may be higher as in many sufferers it is not severe enough to lead them to consult a doctor.

The symptoms include sneezing, nasal secretions and watering eyes, and are most commonly caused by hypersensitivity to pollens - mainly tree pollen in springtime, grass and weed pollen in the summer and, sometimes, mould spores in late summer and autumn.

Butterbur (Petasites hybridus), is a plant native to Europe, northern Africa, and south western Asia. Its leaves and roots contain petasines, shown to inhibit leukotrienes, which may be associated with antispasmodic activity and anti-inflammatory action.

The Swiss and German team behind the latest research undertook the new study as hayfever sufferers often find their work performance and quality of life is affected by the condition, and cast about for possible new treatment methods including, increasingly, herbal sources.

The randomized, double-blind study is published in Phytotherapy Research (Vol 19; Issue 6, pp 530-537). Involving 330 patients in 11 centers, it directly compared the effects of taking an extract containing 8mg of petasin per tablet taken three times a day, the anti-histamine fexofenadine (Telfast 180, one tablet taken once a day) and a placebo.

They found that both butterbur and the anti-histamine were significantly better at reducing symptoms than the placebo - and equally so.

What is more, the butterbur was seen to have a non-drowsy effect - a bonus that could make it particularly useful for patients who can not tolerate this side effect associated with other anti-histamines.

He concluded: “Despite being a herbal drug, Butterbur Petasin has now been subject to a series of well controlled trials and should be considered as an alternative treatment for Hayfever.”

Research has also indicated that the herb’s root may be effective for migraines in adults and children.