Hay fever sufferers must now put up with symptoms for up to two weeks longer than they would have done in the 1990s, according to a major review.
A new report by 65 scientists from around the world found that climate change has "prolonged the pollen season".
The fine powder released by certain grasses, trees and plants can cause chaos for those who are allergic, with itchy eyes, sneezing and headaches all common symptoms.
So what does this mean for millions of people living with hay fever, and is there anything they can do to cope?
The new report, published in the journal Lancet Public Health, says climate change is extending the flowering season of some plants.
