Altitude sickness can result when you’ve moved to high elevations without having time to adjust. When you’re at a mile (5,280 feet) or more above sea level, and especially when you’re higher than 8,500 feet, you may feel symptoms of altitude sickness: shortness of breath, light-headedness, nausea, fatigue, headache, and insomnia. To help your body adjust, drink lots of water, avoid alcohol, and wait a day or two before attempting vigorous activity. If your symptoms are severe, last several days, or worsen, seek medical attention.
Although animals abound in the national parks, the odds of your meeting one face to face, let alone sustaining a bite, are slim (especially if you follow the rules about not feeding them). But if you are bitten or scratched by any wild animal—even a small one—seek medical attention. You may need stitches and antibiotics, or a rabies or tetanus shot. If that animal is a snake, stay calm (if the snake is venomous, a lot of movement can spread the poison). Have someone else get medical help for you right away.
If your body doesn’t have the fluids it needs, you’re dehydrated. Symptoms can range from minor (a dull headache) to life-threatening (seizures, coma). Dehydration is often caused by excessive sweating coupled with inadequate fluid intake, and is a real concern in the national parks, where visitors are generally active (hiking, climbing) but not good at carrying and drinking water. Dehydration is a particular problem for children and seniors and for anyone exercising in dry climates; it’s also more likely at high altitudes. To counter a mild case, drink water or another beverage. Take small sips over a period of time instead of trying to force down a large amount. A serious case requires immediate medical attention. To prevent dehydration, be sure to bring and consume enough water: ½ to 1 quart per person for each hour of exercise.
It’s dangerous—and illegal (you’ll be fined). Animals in many national parks are used to humans being around and may not flee at your presence. But feeding wild animals habituates them to humans and teaches them to look to us for food. When that happens, they lose the ability to hurt or forage on their own, meaning they might starve to death or be hit by cars when looking for handouts. Feeding animals also causes them to be more aggressive, and thus more dangerous, to future visitors. Aggressive animals are removed from areas where they’ll have contact with people; in some cases, they’re relocated, but in others, they’re put down.
Typically caused by excessive exertion in high temperatures such as a strenuous hike in the desert, heat exhaustion or more serious heatstroke can cause nausea, headaches, and dizziness—and even seizures, unconsciousness, and death. If you suspect heat-related illness, rest in a cool, shady place and drink water. Dehydration is often a factor in heat exhaustion and heatstroke. Apply cool compresses to the head, forehead, and trunk. If the victim is unconscious or confused, seek medical help immediately.
When your body gets too cold for too long, hypothermia can develop. Symptoms are chills, fatigue, shivering, and lack of mental clarity. If you or someone you’re traveling with develops hypothermia, seek shelter, remove any wet clothes, and wrap yourself in warm blankets.