Buck Tilton is the co-founder of the Wilderness Medicine Institute of NOLS (WMI). He is the author of the book NOLS Winter Camping, due out next year from Stackpole Books.

Hypothermia and frostbite get most of the headlines when reports on winter medical problems are written—and they deserve the spotlight…most of the time. The consummate outdoor leader, however, packs a few tidbits of knowledge about less common problems, just in case.

Hard exercise on a cold day, the kind of workout that requires aggressive panting, might lead to the winter worry of “frozen lung.” Temps must be low, usually below zero Fahrenheit. No tissue actually freezes, but severe bronchial irritation results from sucking down very cold air faster that the human airway can warm it up. The irritation produces spasms in the muscles of the airway and a burning pain, with the possibility of coughing up blood. Increased mucus production frequently creates wheezing sounds when the sufferer breathes. A severe case might last one to two weeks. Treatment is rest, warm and humidified air to breathe, and plenty of water to drink. Prevention is less painful: Wear a face mask, or breathe through a fluffy scarf.

Another worrisome phenomenon, which can appear with temperatures as high 60 degrees F, is chilblains. When skin is kept cool and moist for a long time, rapid warming causes a rush of blood to the heat-dilated vessels near the surface of a human body. The swollen vessels can’t take the load. Fluid and metabolic waste products leak out of the vessels and into the surrounding tissue. Those tissues swell and itch, and hurt. Pus may fill lesions in a severe case. Treatment includes keeping the damaged skin warm and dry, and applying a protective ointment. Prevention is simple: Keep your skin warm and dry from the start.

The winter sun draws closer to the earth than the summer sun, but because it’s lower in the sky, the radiation is less intense. This healthier aspect of winter exposure is counterbalanced by the fact that snow and ice are very efficient reflectors of sunlight, bouncing 80-85 percent back on the traveler. Even in winter reflected light increases the risk of “sun poisoning,” an allergic reaction to ultraviolet light, primarily UVA. Allergies are specific to certain susceptible people, and this one looks like poison ivy, or, sometimes, eczema. Intense itching usually starts 24-48 hours after exposure. Treatment for most allergies is limited to time, anti-itch measures (topical hydrocortisone and antihistamines), and eliminating contact with the allergy-producing agent. Severe reactions often benefit from prescription drugs that a doctor must provide. Prevention is offered by clothing and sunscreens that block UVA and UVB radiation. Of particular efficacy are sunscreens that contain titanium dioxide.

As the icy tendrils of winter swirled around his house in 1862, Maurice Raynaud took pen in frigid hand to first scratch out the description that would bear his name. Raynaud’s syndrome results from intermittent spasms in the peripheral vessels of fingers or toes, and occasionally ears and nose. Color changes accompany this painful response to cold—usually white, often red or blue. Nobody knows what causes Raynaud’s syndrome, but thousands suffer with the slightest drop in temperature.

Many treatments have been tried, including avoidance of cold (which ruins winter fun), tranquilizers, vasodilating drugs, hormones, and, in extreme cases, a sympathectomy (cutting the sympathetic nerves so the blood vessels can’t constrict).

In recent decades, researchers at the U.S. Army Research Institute of Environmental Medicine (USARIEM) have been experimenting with techniques to counter-condition these syndrome-impaired nervous systems. (Current research at USARIEM will be touched on in the upcoming NOLS Winter Camping book, due out next year.) Test subjects were required to keep their distressed parts in hot water for 15-20 minutes while the rest of their bodies stayed cold. Then, with hands or feet still in hot water, they were moved to a warm ambient environment for 15-20 minutes. After doing this a couple of times a day, eventually, depending on the severity of the case, the brain is conditioned to keep the peripheral vasculature open, without the hot water, despite the changing air temperature. Sometimes it doesn’t work, but the Institute says 90 percent of their patients improve and conditioning may last for years before it has to be repeated.

In any case, Raynaud’s rarely goes away on its own, and sufferers are well-advised to seek medical aid before frostbite once again takes the spotlight…and the finger.

But, despite the “worries” of winter, the cold outdoors offers rewards that can only be found in a world blanketed softly and without prejudice by untracked white. Pack your pack…and then go.