Cusco sits at 3,400 metres and most visitors arrive by plane from sea level, which is the fastest possible way to gain altitude. Some degree of discomfort is normal. Knowing which remedies do something and which are folklore saves a lot of wasted days.

This article is general information, not medical advice. Anything you take is a conversation to have with your own doctor before you travel, especially if you take other medication or have a heart or lung condition.

What altitude sickness actually is

At 3,400 metres there is roughly a third less oxygen in each breath than at sea level. Your body compensates by breathing faster and producing more red blood cells, and that adjustment takes days.

Acute mountain sickness is the mild, common form: headache, poor appetite, broken sleep, mild nausea, feeling short of breath on stairs. It usually appears six to twelve hours after arriving and eases within two or three days.

The dangerous forms are rare but real: fluid on the lungs or the brain. Signs are breathlessness at rest, a wet cough, confusion, loss of coordination or a headache that will not respond to anything.

Acetazolamide, the one with evidence behind it

Acetazolamide, sold as Diamox among other names, is the drug with the strongest evidence for preventing acute mountain sickness. It works by mildly acidifying the blood, which pushes you to breathe more and speeds up acclimatisation rather than masking symptoms.

It is prescription-only in most countries, and it is usually started a day or two before going high. Your doctor sets the dose; do not copy one from a forum.

The side effects are worth knowing because they surprise people: tingling in fingers and toes, needing to urinate much more, and fizzy drinks tasting strange. None of that is dangerous, but it is disconcerting if nobody warned you.

It contains a sulfonamide, so it is not for everyone. That is precisely the sort of thing your own doctor needs to check.

Soroche pills, sold on every corner

In Cusco pharmacies you will find sorojchi pills without prescription. They are typically a combination of aspirin, caffeine and salophen.

What they do is treat the headache. What they do not do is speed up acclimatisation. That is a real difference: you feel better while your body is still adapting at exactly the same rate.

That is not useless, but it does carry a risk. Feeling fine because of painkillers can push you into doing more than your body is ready for, and it can mask a symptom you should be paying attention to.

Coca leaves and coca tea

Chewing coca leaves and drinking mate de coca is the traditional Andean approach and it is offered everywhere, usually free in hotel lobbies.

It helps with mild headache, tiredness and nausea, and many travellers find it genuinely settling. What it does not do is prevent altitude sickness or replace acclimatisation.

Two practical notes: coca can show up on a drug test, which matters if your job involves them, and taking coca leaves out of Peru is illegal in most countries.

Oxygen

Hotels, tour vans and clinics in Cusco offer bottled oxygen. It gives immediate relief for fifteen or twenty minutes.

It is a rescue measure, not a treatment. Once the mask comes off you are at 3,400 metres again with the same amount of adapting still to do. Useful in a bad moment, useless as a plan.

What works better than any of it

Arrive and do nothing for two days. No trek, no Rainbow Mountain, no long day tour. This is the single most effective thing on the list and it costs nothing.

Drink more water than feels necessary, eat lighter than usual and favour carbohydrates, and skip alcohol for the first two days. Alcohol at altitude on a dehydrated body hits much harder than expected.

Sleep lower than you climb when you can. A night in the Sacred Valley, around 2,800 metres, is a gentler introduction than a first night in Cusco.

Walk slowly. Slower than feels natural, especially on stairs. Most first-day headaches come from arriving and immediately walking uphill with luggage.

When to stop and descend

Descend, and get medical help, if there is breathlessness while resting, a cough with frothy or pink sputum, confusion, trouble walking in a straight line, or a headache that does not improve with rest and painkillers.

Going down even 500 metres usually produces rapid improvement. Nothing in a pharmacy substitutes for that, and no itinerary is worth ignoring it.

Reviewed August 2026. Check current guidance with your doctor before travelling.