What this solves
"I have a headache" at altitude means four different things. Drinking 2 L and waiting decides dehydration. Ibuprofen and a rest day decides exertion. Watching it worsen decides AMS. Watching it get worse still, with ataxia or vomiting, decides HACE precursor — and you descend. This tool forces the question pattern instead of letting you reach for ibuprofen by reflex.
Describe the headache
How to read the result
The four diagnoses are scored against your answers. A score > 60 is the working diagnosis. Two adjacent diagnoses (e.g. dehydration AND AMS) is common — fix the more dangerous one first.
Dehydration — Often frontal, fixes with water. Common on a sunny day above 4,000 m when humidity is < 30 %.
Exertion — Tension-band / whole-head, comes after effort, fixes with ibuprofen + rest. Benign.
AMS — Frontal, present on waking, persists despite water + ibuprofen. Often paired with nausea or poor sleep. Treat as AMS — score yourself, do not push higher.
HACE precursor — Occipital, continuous > 24 h, NOT responding to anything, paired with vomiting or ataxia. Descend now.
Limitations
FAQ
A: Probably worse. Alcohol at altitude dehydrates you AND depresses ventilation overnight. If you drank in Daocheng last night, this is hangover, but it lowered your AMS margin — re-check symptoms before going up.
A: Stooping raises intracranial pressure briefly. Frontal pain worse on bending is more likely sinus or dehydration than AMS. Sinus pain is sharp / localised behind the cheekbones.
A: If the headache was exertion-driven, yes. If it's AMS-masked, you've just hidden the warning sign. Don't ascend within 12 h of an AMS-pattern headache that needed ibuprofen.
A: Yes. Personality change + headache above 4,000 m is part of the HACE precursor pattern. Treat the symptom, not the mood.