Altitude sickness effects and warning signs

Lower oxygen availability after a climb makes the body work harder to adapt. Early altitude sickness often presents with a headache plus symptoms such as queasiness, weakness, light-headedness or restless sleep. The word ‘side effects’ can be confusing here: these are effects of the illness, not necessarily reactions to a medicine.

A faster climb, a higher sleeping elevation and previous susceptibility can matter. Physical fitness does not reliably prevent illness, and symptoms should not be dismissed as simply being out of shape.

Stop gaining elevation when symptoms appear. Rest, avoid strenuous activity and alcohol, keep comfortably warm, and take ordinary fluids and food as tolerated. Tell a travel companion how you feel so changes in speech, alertness or balance are not missed.

Do not resume ascent while symptoms continue. If they intensify or do not settle at the same elevation, descend and obtain medical advice. A clinician can distinguish altitude illness from problems such as infection, migraine, medication effects, low blood sugar or dehydration.

Trouble walking steadily, confusion, marked sleepiness, breathlessness while resting, chest congestion, a worsening cough, collapse or blue-grey colouring around the lips requires urgent action. These features can reflect dangerous effects on the brain or lungs. Arrange assisted descent and emergency care without waiting for morning or for symptoms to pass.

Repeated vomiting, inability to drink, a severe persistent headache or rapid deterioration also warrants prompt assessment. Never leave a confused or unsteady person to travel down alone.

Ask whether your itinerary allows adequate acclimatisation and whether heart, lung, blood or neurological conditions affect your plans. If medication is considered, clarify its purpose, expected adverse effects, important interactions and whether it changes the rule against climbing with symptoms.