Acute Mountain Sickness vs. Migraine: Telling Them Apart

The clearest separators are these. Altitude headache is usually on both sides of the head, dull and pressing, arrives six to twelve hours after gaining altitude, is worse at night and on waking, and improves when you go down. Migraine is usually one-sided, throbbing, comes with light and sound sensitivity and sometimes aura, follows your own established pattern, and responds to your usual acute medication. Altitude headache responds to descent and to oxygen; migraine largely does not. When the two are genuinely indistinguishable, treat it as altitude sickness — because that is the diagnosis where getting it wrong is dangerous.

Altitude can also trigger a real migraine attack in someone who gets them, which means both can be true at once.

Why the confusion is reasonable

Both produce a headache with nausea. Both can involve dizziness. Both can be worse in bright mountain light. Both often start in the morning. And people who get migraines are, on the available evidence, somewhat more likely to develop symptoms at altitude than people who do not — so the population most likely to face the question is also the population most at risk of both.

The overlap is not just coincidence. Altitude produces a mild hypoxic stress, changes in cerebral blood flow, disturbed sleep, dehydration, exertion and often skipped meals. Every item on that list is a recognised migraine trigger in its own right. A trek at 3,500 metres is close to a controlled experiment in stacking triggers.

Side by side

Location. Altitude headache is typically bilateral, frontal or generalised, felt as pressure or a band. Migraine is unilateral in the majority of attacks, though not all, and often changes sides between attacks.

Character. Altitude headache is dull, heavy, pressing. Migraine is classically pulsating or throbbing, and worsens with routine physical activity in a way that is quite distinctive.

Timing. Altitude headache appears six to twelve hours after arriving at a new height, is worst overnight and in the early morning, and eases through the day as acclimatisation proceeds. Migraine timing follows your own pattern and has no particular relationship to when you gained altitude.

Associated symptoms. Altitude headache comes with loss of appetite, unusual fatigue, dizziness, and broken sleep with periodic breathing. Migraine comes with photophobia, phonophobia, osmophobia, nausea and vomiting, and in perhaps a third of people a visual, sensory or speech aura beforehand.

Aura. Aura is close to diagnostic for migraine. Altitude sickness does not produce a spreading visual scintillation or a marching sensory disturbance. There is a rare entity called high altitude retinopathy, and a rarer one where altitude appears to provoke aura without headache, but a classic 20-to-60-minute expanding visual disturbance points firmly at migraine.

What helps. Altitude headache improves with descent, with supplemental oxygen, and with time as you acclimatise, and it responds only partially to ordinary analgesia. Migraine responds to triptans and your usual acute treatment, to a dark quiet room, and to sleep, and it does not care much about oxygen — with the notable exception of cluster headache, which does respond to high-flow oxygen and is a different condition again.

Prior history. If you have had dozens of these before at sea level and this feels identical, it is probably a migraine. If you have never had a headache like it and you arrived at 3,600 metres yesterday, the altitude explanation is more likely.

The single most useful test

Descend 500 to 1,000 metres and see what happens.

An altitude headache improves markedly, often within hours, and sometimes remarkably quickly. A migraine attack does not care what altitude you are at and will run its usual course.

This is diagnostically useful, but it is also the correct management for suspected altitude sickness regardless. That is the practical resolution of the whole question: when you cannot tell, the action is the same as if it were altitude sickness, and the cost of descending unnecessarily is a lost day.

When it is both

This is common and worth naming explicitly. Someone with a migraine history arrives at altitude, develops mild acute mountain sickness, sleeps badly, and that stack of triggers sets off a full migraine attack on top.

The practical approach is to treat both. Take your usual acute migraine medication, and simultaneously stop ascending, hydrate, rest, and consider descent if symptoms do not settle. Triptans are not contraindicated at altitude for most people, but if you have cardiovascular risk factors it is a conversation to have with your doctor before the trip rather than at 4,000 metres.

Do not let a successful migraine treatment reassure you into ascending. Suppressing the pain does not mean the acclimatisation problem has resolved.

The red flags that override everything

Whatever you think the headache is, these signs mean immediate descent and medical help:

• Confusion, altered behaviour, or drowsiness that is difficult to rouse
• Ataxia — an unsteady, drunken gait, or failing a heel-to-toe walking test
• Breathlessness at rest, or a cough producing frothy or pink sputum
• Any new weakness, numbness or speech disturbance that does not resolve within an hour
• A headache that arrived suddenly at maximum intensity

The last two need particular care. A migraine aura resolves within an hour, typically 20 to 60 minutes, and a thunderclap onset is never a normal migraine. Neither is safe to explain away as altitude.

If you are a migraine sufferer planning a high trip

Ascend slower than the guidance suggests. Above 3,000 metres, keep sleeping-altitude gains to 300 metres a night with regular rest days, and give yourself more margin than an average party would.

Keep your preventive medication going. Travel is exactly when routines break down, and it is the worst time to lapse.

Carry enough acute medication, in hand luggage, in its original packaging. Attack frequency often rises on a trip.

Protect sleep and meals aggressively. These are your controllable triggers, and altitude is not one of them.

Discuss acetazolamide with your doctor beforehand. Speeding acclimatisation removes one of the triggers from the stack.

Take sunglasses seriously. Ultraviolet intensity increases roughly 10 to 12 per cent per 1,000 metres, and glare off snow is a well-recognised trigger.

Where pressure tracking fits

If you already log symptoms against the barometer, an altitude trip gives you the extreme end of the scale for comparison. A weather system might move your local pressure by 20 to 40 hectopascals over a day or two. Arriving at 3,500 metres is a sustained drop of well over 300 that does not come back until you descend.

That contrast is informative. Someone whose symptoms track fast weather changes but who does fine at a stable high altitude is probably reacting to the rate of change. Someone who is fine in storms but struggles at height is more likely reacting to the sustained low itself. Comparing your log across both — a mountain trip against a season somewhere with an active barometer like Derry, New Hampshire or Gallatin, Tennessee — is one of the few ways to separate the two.

FAQ

Does having migraines mean I will get altitude sickness?

Not necessarily, but studies suggest migraine sufferers report altitude symptoms somewhat more often. Treat it as a reason for a more conservative ascent profile rather than a reason to stay home.

Can I take a triptan at altitude?

For most people yes. Triptans cause mild blood vessel constriction, so anyone with cardiovascular risk factors should get individual advice before the trip.

Does oxygen help a migraine?

Not typically. High-flow oxygen is an effective treatment for cluster headache, which is a different condition. A clear response to oxygen at altitude points toward altitude sickness rather than migraine.

How fast should an altitude headache improve after descending?

Often within a few hours, sometimes faster. Little or no improvement after descending 500 to 1,000 metres suggests something else is going on.

Is altitude headache the same as acute mountain sickness?

Headache is the required symptom of acute mountain sickness, but the diagnosis also needs at least one of nausea, fatigue or dizziness. A headache alone at altitude is sometimes called high altitude headache and is a milder entity. The full symptom picture is covered in altitude sickness symptoms.

What if I get an aura at altitude for the first time?

A first-ever aura at any age deserves medical assessment rather than being attributed to the mountain. Descend and get it looked at.

The short version

Bilateral, dull, arrived overnight after gaining height, with nausea and bad sleep, and better on descending: altitude. One-sided, throbbing, with light sensitivity or aura, matching your usual pattern, and better with your usual medication: migraine. Both at once is common. And when you genuinely cannot tell, go down — that decision is right either way.

Want to compare altitude against the pressure changes you get at home? Track them with Pressure Pal.