Wilderness first aid is different from street first aid in one critical way: you can't call 911 and wait ten minutes. You may be hours from a road, miles from cell service, and the first responder is you.
This article covers the skills most relevant to day hikers and weekend backpackers. It is not a substitute for a Wilderness First Aid (WFA) course — if you do serious hiking, take one. NOLS offers them for $250-350; it's two days and legitimately changes how you think about trail risk.
The Patient Assessment System
When something happens, stop and assess before acting. The mnemonic is ABCDE: Airway, Breathing, Circulation, Disability (spine/head), Exposure (take off gear, look for injuries). This systematic approach prevents missing a serious injury while treating a minor one.
Blisters
The most common trail injury. Do not pop a blister in the field unless it's on a weight-bearing surface and too painful to walk. If you must drain it: sterilize a needle with flame, puncture at the edge, keep the roof intact, cover with moleskin. A blister that gets infected in the backcountry is a serious problem.
Ankle Sprains
Second most common. RICE: Rest, Ice (cold stream water works), Compression (wrap with an ACE bandage or use trekking pole compression), Elevation. The critical decision: can the patient bear weight? If yes, hiking out slowly is usually possible. If no, you need help and potentially a rescue. Don't let someone try to hike out on a fractured ankle — the difference between a sprain and a fracture requires an X-ray, but inability to bear any weight is a red flag.
Hypothermia
Hypothermia can occur at temperatures well above freezing — wet plus wind is the dangerous combination. Signs: uncontrollable shivering, confusion, poor coordination. Treatment: get them dry, insulated, and out of wind. Warm sugary fluids if conscious. A hypothermic person should not be left alone. In the field, a sleeping bag with another person inside is faster warming than any other method.
When to Call for Rescue
Call or send for rescue when: the patient cannot safely self-evacuate, vital signs are deteriorating, you have a head injury with loss of consciousness, suspected spinal injury, inability to bear weight on a lower extremity, or any signs of internal bleeding. Don't wait to see if things get better. Call earlier than you think you need to.