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Outdoor First Aid

How to Treat Allergic Reactions in the Backcountry

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I took my first bite of energy bar at the same time I read the wrapper: cashews. I’m allergic to cashews. We were two days’ hike from the nearest road and nowhere close to cell service. I thankfully spit out the stuff before experiencing the itchy, anxious, lump-in-the-throat feeling that I’ve unfortunately come to recognize, but the near miss reminded me to review my wilderness plan for allergic reactions.

Allergy symptoms vary widely, from hives or itchy eyes and sneezing on high-pollen days, to real respiratory distress. Allergic reactions also commonly include skin rashes, vomiting or diarrhea, shortness of breath and wheezing, even dangerous airway swelling. 

Most common allergy triggers are environmental—like stings, pollen, or animal exposure—or related to specific foods such as peanuts, tree nuts, or shellfish. Some food sensitivities have been on the rise: Peanut allergies in children, for example, increased more than 20 percent between 2010 and 2017. The rate of allergic reactions reported by students on NOLS expeditions between 2005 and 2019 tripled when compared to the prior 20-year period. 

Bee stings are a common cause of allergic reaction for hikers. (Photo: © Philippe LEJEANVRE/Moment via Getty Images)

For most reactions, over-the-counter medications provide a first line of defense. Some meds are more sedating than others, which can be a real concern during outdoor activities. Medication can blunt or prevent some allergic symptoms (like annoying seasonal allergies) or provide effective first aid for minor reactions. Oral antihistamines like diphenhydramine (Benadryl) or cetirizine (Zyrtec) are a high-yield addition to just about any med kit. Anti-allergy eye drops provide quick relief for scratchy, runny eyes and don’t take up much extra space or weight.

Anaphylaxis—a severe, life-threatening allergic reaction—presents with severe shortness of breath or wheezing, airway obstruction like swollen lips, tongue, and throat, or even low blood pressure and unconsciousness. In the wilderness, anaphylactic reactions happen rarely, although it’s difficult to estimate how often. Over a 15-year period in which Outward Bound enrolled over 40,000 students per year, the educational organization reported a total of 46 anaphylaxis cases from the field. Most of those were related to insect stings, with a smaller number due to peanuts, tree nuts, or other causes. 

Thankfully, anaphylaxis can be treated effectively in the backcountry using epinephrine. Epi is a powerful, super-fast acting hormone that can reverse life-threatening respiratory or airway problems. Epi autoinjectors provide a rapid injection with a pen-like device, usually jabbed in the outer thigh. Many nonmedical professionals who provide care in the outdoors (guides, rangers, etc.) have been trained in epinephrine use and can administer it safely, and anyone with a history of a severe allergic reaction should have access to an autoinjector. 

In resource-limited settings, we may hesitate and wonder if it’s worth burning through the only epi available or waiting to see how things go. First responders should err on the side of caution. Epi works really well with few side effects. That said, a few sneezes on a high-pollen day don’t justify stabbing yourself in the thigh with powerful medication. 

Those of us with food or environmental allergies won’t escape the occasional itchy eyes or scratchy throat—but with adequate preparation, we can avoid outcomes that are terribly uncomfortable, or worse. Carrying allergy medication and maintaining awareness of risky situations—whether potential exposure to an offending food or increased chance of insect stings—reduces the risk. If there’s an epinephrine autoinjector in the bottom of your pack somewhere (or even better, immediately accessible), tell your trail companions. They may end up saving the day for someone you come across in the backcountry, themselves, or even you. 

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