A headache at altitude could be a mild, self-limiting altitude headache, the first sign of a life-threatening cerebral edema, a migraine triggered by altitude stress, or simply a dehydration headache. Distinguishing between them matters because the treatment and appropriate response differ dramatically. I've seen climbers dismiss a dangerous AMS headache as "just the altitude" and continue ascending. I've also seen climbers descend unnecessarily for headaches that were clearly dehydration-related. The difference in outcomes between these two errors is significant.
The Altitude Headache: AMS as the Cause
Altitude headache associated with Acute Mountain Sickness is one of the most common symptoms of AMS, occurring in the majority of people who develop the condition. The headache is typically described as a bilateral pressing or tightening sensation (not throbbing), worse in the morning and with exertion, and may be accompanied by other AMS symptoms: nausea, fatigue, dizziness, and sleep disturbance.
The diagnostic approach: if you're above 2,500m and develop a headache, assess yourself for other AMS symptoms using the Lake Louise Score system. Score yourself on: headache (0-3), gastrointestinal symptoms (nausea, vomiting, 0-3), fatigue and weakness (0-3), dizziness (0-3), and sleep disturbance (0-3). A total score of 3 or more with headache present indicates AMS.
Altitude headache that is part of AMS responds to: stopping ascent, rest at the current altitude, hydration, and ibuprofen (600mg every 8 hours). If symptoms improve with these interventions, you likely have mild AMS and can consider resuming ascent once symptoms resolve. If symptoms do not improve within 24 hours, or if they worsen, descend.
Dehydration Headache
Dehydration headache is caused by fluid loss and presents with symptoms that overlap with altitude headache but have distinguishing features. Dehydration headache is typically: improved by rehydration, worse with physical activity, accompanied by dry lips and dark urine, and not accompanied by the other AMS symptoms (nausea, fatigue, sleep disturbance) unless dehydration and AMS are co-occurring.
At altitude, dehydration and AMS co-occur frequently because altitude increases fluid loss while simultaneously dulling thirst sensation. A climber with a headache at altitude who is also dehydrated is dealing with both problems, and addressing only one may not resolve the headache. The practical approach: hydrate aggressively (2-3 liters of water over 2-3 hours) while monitoring urine color and AMS symptoms. If the headache resolves as hydration improves, dehydration was the primary cause. If the headache persists despite adequate hydration, assume AMS.
Migraine at Altitude
Migraine is a primary headache disorder that can be triggered or worsened by altitude stress, dehydration, and changes in sleep patterns — all common at altitude. Migraine presents with: unilateral (one-sided) throbbing or pulsating pain, photophobia (sensitivity to light), phonophobia (sensitivity to sound), nausea and sometimes vomiting, and prodrome symptoms (visual aura, sensory changes, language disturbance) in some cases.
Altitude-related migraine is distinguished from AMS headache by: the unilateral nature (AMS headache is typically bilateral), the presence of photophobia and phonophobia (more severe in migraine), and the absence of other AMS symptoms beyond the headache. Migraine at altitude is treated with standard migraine protocols: dark environment, quiet, triptans or ibuprofen if available, and anti-nausea medication if needed.
The complication is that migraine and AMS can co-occur — a migraine-prone climber who develops AMS may experience migraine-like symptoms as part of the overall AMS presentation. The distinguishing factor is response to AMS treatment (descent, rest, ibuprofen). If the headache improves with descent, AMS was the primary driver. If the headache has migraine-specific features and doesn't respond to AMS protocols, treat as migraine.
When the Headache Might Be More Serious
Certain headache presentations should be treated as medical emergencies. These include: headache that is the worst headache of the person's life, headache accompanied by confusion, stumbling, personality change, or loss of coordination (these suggest HACE), headache accompanied by shortness of breath at rest, persistent cough, or blue lips (these suggest HAPE), and headache following a head injury (suggesting intracranial bleeding).
HACE and HAPE are the life-threatening forms of altitude illness. The headache is one of many symptoms, and by the time these severe forms develop, the headache is accompanied by other clear danger signs. When in doubt, descend. The descent itself is often the most effective treatment, and the risk of descent almost always outweighs the risk of waiting at altitude.
Medication Considerations
For altitude-related headache, ibuprofen (600mg every 8 hours) is effective and widely used. Acetaminophen (paracetamol) is less effective than ibuprofen but is an alternative for those who can't take NSAIDs. For nausea associated with AMS, promethazine or ondansetron can help. See our Altitude Medications Guide for detailed dosing information.
Never use sleeping medication (sedatives) at altitude to treat sleep disturbance — this can suppress respiration and worsen altitude illness.
Related Articles
- Altitude Sickness Complete Guide — Full coverage of AMS, HACE, and HAPE
- Acclimatization Science — Understanding why altitude causes these symptoms
- Altitude Medications Guide — Medication dosing and protocols