Christmas Tree Syndrome Season Underway

Pine scent and mold spores that grow on Christmas trees are among a host of potential reaction triggers during the indoor allergy season, allergists say.

Christmas trees can make you sick.

Awareness of the outdoor allergy seasons is widespread among healthcare providers and the public: tree pollen in the spring, grass pollen in the summer and weed pollen in the fall. But knowledge about the indoor allergy season during the late fall and winter, including a phenomenon some allergists call Christmas Tree Syndrome, is relatively scant.

"Once the weather gets colder and the heat comes on, it's one of my more traumatic times of the year," says Dean Mitchell, MD, president of New York-based Allergy Advances Medical.

Pine scent and mold spores that grow on Christmas trees are among a host of potential reaction triggers during the indoor allergy season, he says. Other indoor allergens include dust and mold from heating systems, pet dander, and dust mites, which are present in many indoor environments from bedding to airline seats.

When people make holiday visits to the homes of friends and family members, "they encounter an environment that could be problematic," Mitchell says, noting that pet dander and dust are prime allergy suspects under this scenario.

Symptoms linked to mold on Christmas trees may include head congestion, itchy eyes, headaches, skin rashes and bronchitis.

A study presented in 2007 at the annual scientific meeting of the American College of Allergy, Asthma, and Immunology demonstrates the potential for live Christmas trees to increase indoor mold counts several fold. The research was conducted by Rebecca Gruchalla, MD, PhD, of University of Texas Southwestern Medical Center in Dallas and John Santilli Jr., MD, of St. Vincent Medical Center in Bridgeport, CT.

After placing a live pine tree in a room heated at about 66.5 degrees, Gruchalla and Santilli collected mold count data for two weeks. The mold count rose from 800 spores per cubic meter of air to 5,000 spores per cubic meter.

Mold and fungus grow naturally on pine trees, particularly in the fall, says Robert Arnold, MD, a family medicine physician in Colorado who works at Birmingham, AL-based AFC/Doctors Express Urgent Care. Once a Christmas tree is brought into a home's warm environment, "spores proliferate exponentially," he says.

Gauging the Threat
When asked about the prevalence of allergic reactions to Christmas trees among their patients, allergists interviewed reported a widely variable level of cases.

"In my 20 years of practice, I've seen two cases of this issue," Mitchell says.

Arnold and Clifford Bassett, MD, a New York-based allergist who serves as spokesman for ACAAI, say they have treated many more patients for Christmas tree-related allergic reactions.

Bassett, who says that about 15% of allergy patients are sensitive to mold allergens, embraces the term Christmas Tree Syndrome. Tips to mitigate allergy problems linked to Christmas trees are on his "list of the Top Ten ways to avoid holiday allergic reactions."

Mike Tringale, MS, senior VP of external affairs for the Washington, DC-based Asthma and Allergy Foundation of America, says there is a spike in allergy service utilization in December, but the increased patient traffic is not driven primarily by Christmas trees or other holiday-season allergen sources such as scented candles.

"Flu is the Number One trigger for asthma from November to January," he says.

During the cold months of the year, patients who experience suspected allergic reactions and their physicians should cast a wide net to find the allergen triggers, Tringale advises. "The truth is, allergy is a very complex disease," he says. "Sometimes, you don't see all the triggers that are around your house."

Avoidance Strategies
Arnold, who is 62, says he broke a lifelong habit after learning about the mold threat from Christmas trees. "I used to cut a tree every year and tried to keep the tree as pristine as possible," he says. Now he has a new routine. "The easiest thing to do is just to wash it off with water and set it outside in a bucket to dry off."

It may be stressful for cost-conscious people during a cold snap, but Mitchell says opening the windows of a home for 15 minutes can have a significant impact on reducing airborne allergens.

He also advises spraying live trees with a weak bleach solution to combat mold and cautions that artificial trees can gather dust during storage that trigger allergic reactions. "You need to make sure that's cleaned up very well," Mitchell says.

While people with a history of allergic reactions to trees and plants may benefit from purchasing an artificial tree, "a synthetic tree is not necessarily the best option," Tringale says. That's because chemicals on fake pine trees can trigger asthma. "Buyer beware: some synthetic trees are better than others."

When asked whether allergists have declared war on Christmas trees since the release of the 2007 mold study, Tringale had a concise answer. "No. Definitely not. Remember, not everybody is allergic to everything."