It's the season to be merry, but one holiday tradition may be making you sick — medical experts say some people are discovering they're allergic to Christmas trees.

"They'll get itchy eyes, runny nose, sneezing, wheezing, just as if it was a spring pollen season," said Vancouver allergist Dr. Ross Chang.

Chang said that in recent days, about half a dozen of his patients have come in with those complaints.

"It happens often when they're close to the tree. It's either the mould spores that are released from the tree as it dries out indoors or sometimes it's due to the smell or fragrance of the tree," said Chang.

The cure is simple, said Chang — leave the room, buy an artificial tree or take an antihistamine.

Lower Mainland commercial plant expert Wim Vander Zalm said it’s news to him.

"I’ve never heard of people being allergic to Christmas trees," said Vander Zalm, of Art Knapp Plantland and Florist.

But he admitted it might be possible.

“When a tree is more acidic it is more likely to grow mould or bacteria or moss or lichens," Vander Zalm said. And Douglas firs and cedars are both highly acidic but between the two, only the fir is a popular Christmas tree.

If you're intent on getting a real Christmas tree, Vander Zalm suggests selecting a variety of tree less likely to bring in mould and to clean the tree — even hose it off before bringing it inside.

"Definitely suggest the Fraser fir as the best option. It's a very smooth bark and you never really see any types of mosses or lichens growing on a Fraser fir. Very seldom," said Vander Zalm.

With files from the CBC's Meera Bains