A warning this holiday season about something that is called "Christmas Tree Syndrome" where people get sick from being around the tree.
A centerpiece of the season: the Christmas tree and the real ones are a beautiful tradition from nature.
But real trees can trigger an allergic reaction with symptoms that can include: wheezing, coughs, congestion, sore eyes and potentially life-threatening asthma attacks.
One way to reduce the risk? A good shake can get rid of some dust and pollen.
But the branches and trunk can often hold onto another microscopic problem.
"What they're allergic to is the mold that settles on the tree during its growing time and arguably sometimes when it's waiting to be sold here on the lot," said Jimmy Coan, who's a Christmas tree farmer.
One study found the mold count from a live Christmas tree rose to five times the normal level two weeks after the tree was brought indoors.
Another way to make the tree less likely to trigger an allergic reaction is to give it a bath.
"Get your tree in the backyard and hose it down. Then put it in the house and you're good to go," Coan said.
Allergists recommend a thorough spraying of the branches and trunk and then letting it dry outside for a day.
Doctors say another possible allergy issue is the water in tree stands can grow mold.
"You might to be careful about getting someone else to add water to the tree because that stirs up the mold that's in that reservoir," said allergy specialist Dr. Albert Gros.
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Doctors say people with these allergies should probably only keep a live Christmas tree in the house for only four to seven days.
For people who are highly allergic, doctors say it's probably best to avoid live Christmas trees altogether.