Pine: The Pollen with a Bad Rap

Written by Dr. Joel Gallagher, Allergy and Asthma Center of NC, Cone Health Medical Group

Ahhhh… the sweet smell of pine. The smell of the winter holiday season. The smell of that quintessential cleaning solution that my mom used to clean just about anything around the house when I was growing up. Pine definitely brings me back to where I grew up in northern Louisiana. Pine trees were everywhere (including several 100+ year old pine trees in my own backyard). The names of establishments around my hometown literally began with “Piney Hills” (Piney Hills Golf Course, Piney Hills Tackle Shop, etc.). Pine trees are a big part of my new home here in North Carolina as well, although hardwoods tend to be more prominent in the Piedmont Triad.

It was always taught during my fellowship and all board review books that pine (member of the genus Pinus) is a non-allergenic pollen. Although it gets a LOT of the blame for spring allergy symptoms (at least where I grew up in the piney hills region of Louisiana) since it tends to be the predominant pollen that covers everything, its large size and low overall protein level are thought to be a minor actor in the allergenic theater of our lives. Its proteins are also encased in a waxy, hydrophobic (think fat-containing) layer that prevents its protein from releasing into the surrounding tissues.

Image 1 (taken by Forsyth County staff on April 8, 2025): Three pollen grains from the pine family shown under a microscope at 40x magnification. The pink color is from a dye called Calberla’s stain that is used to make pollen grains easier to see for counting and identification. Pine pollen is larger than most other pollen grains, ranging from 60-100 microns in diameter.

Its non-allergenic label is so engrained that pine pollen is often used as a NEGATIVE control in nasal and bronchial challenge tests in the clinical setting. This long-held belief might not always be the case, however. There is some cross reactivity between pine pollen and grass pollen. Likewise, there is some cross reactivity between pine and members of the Oleaceae family (olive family), which includes privets (Ligustrum spp.) that are commonly found in the Piedmont Triad.

Symptoms from most pine pollen allergies (as well as other tree allergies) occur in the spring when the tree pollen levels are elevated. Interestingly, this is a distinct reaction compared to that experienced when you put a fresh Christmas tree in your house and start having allergic rhinitis symptoms. By the time the holiday season rolls around, tree pollen is long gone. Reactions to Christmas trees are typically due to either late fall weed pollens that enter the home on the tree itself or, more commonly, mold present on the trees.

One question we often are asked when a patient is allergic to pine is whether they can safely eat pine nuts. Pine nuts are the inner parts of cones harvested from any one of several Pinus species. They have been eaten as an excellent source of nutrition for over 2000 years, starting in the Mediterranean region, and contain saturated fatty acids, potassium, phosphorus, magnesium, zinc, and vitamin B1 and B2. They are often added to hummus as well as pesto. Consumption of pine nuts has increased as the Mediterranean diet has taken off. Although a few cases are associated with allergies to other tree nuts, most patients with a pine nut allergy are monosensitized (meaning they do NOT have allergies to other tree nuts). Thankfully, there is very little chance of cross-reactivity between the proteins of the pine pollen and the proteins of the pine nut. So, happy eating!