Altitude Sickness Medication in Spain: What Tourists Need to Know About Prevention

Physical fitness does not protect you from altitude sickness. That is the single most misunderstood fact about this condition, and it catches well-prepared hikers and climbers off guard every year in Spain's mountains. Whether you are summiting Mount Teide in Tenerife at 3,718 metres, crossing high passes in the Pyrenees, or trekking Mulhacén in the Sierra Nevada, altitude sickness medication in Spain requires a prescription — and getting one before your ascent is the most effective thing you can do to stay safe.

What's Happening in Your Body at High Altitude

At sea level, each breath delivers a reliable amount of oxygen to your lungs. As you climb, air pressure drops. At 3,500 metres — roughly the altitude of Teide's summit or Mulhacén — each breath contains about 36% less oxygen than it would at sea level.^[1] Your body has the same demand for oxygen, but the supply has shrunk.

Your body tries to compensate. Your breathing rate increases. Your heart pumps faster. Your kidneys begin adjusting blood chemistry to help your blood carry oxygen more efficiently. This process — acclimatisation — takes 24 to 72 hours. The trouble starts when you ascend faster than your body can adapt.

When acclimatisation falls behind, fluid begins to leak from small blood vessels into surrounding tissues. In the brain, this causes swelling. That swelling is what produces the headache, nausea, and dizziness of acute mountain sickness. It is the same basic mechanism as a bruise — fluid where it should not be — except it is happening inside your skull.^[2]

Speed of ascent is the biggest risk factor. Someone who drives to Teide's base station and hikes to the summit in a single day is far more vulnerable than someone who spends a night at 2,500 metres first. Prior altitude sickness is the second strongest predictor. If it has happened to you before, it is likely to happen again at the same altitude unless you take preventive medication.^[3]

What You'll Feel — and When Symptoms Appear

Symptoms of acute mountain sickness typically appear 6 to 12 hours after arriving at altitude above 2,500 metres, though they can begin as early as 2 hours in rapid ascents. The headache comes first. It is usually a dull, throbbing pressure across the front of the head, worse when bending over or lying flat. It does not respond well to paracetamol alone.^[1]

Alongside the headache, you may feel nauseous, fatigued, or dizzy. Appetite drops. Sleep becomes fragmented — many people wake repeatedly during their first night at altitude, sometimes with a sense of breathlessness. These symptoms are your body's alarm system telling you that acclimatisation has not caught up with your elevation.

In most cases, mild altitude sickness resolves within 12 to 48 hours if you stop ascending. But if you continue climbing while symptomatic, mild sickness can progress to high-altitude pulmonary oedema (fluid in the lungs) or high-altitude cerebral oedema (severe brain swelling). Both are medical emergencies. Prevention is the entire strategy here — once severe symptoms develop, the only reliable treatment is descent.^[2]

The Medications a Doctor Will Prescribe

Altitude sickness prevention centres on one well-studied drug: acetazolamide. A second prescription option, dexamethasone, is reserved for treating moderate-to-severe cases. Ibuprofen is available without a prescription and has emerging evidence for mild prevention.

What You Can Buy at a Spanish Pharmacy

Spanish pharmacies — farmacias — cannot sell you acetazolamide or dexamethasone without a receta médica (prescription). Both are strictly prescription-only across Spain. What the pharmacy can provide without a prescription is ibuprofen, paracetamol, and electrolyte rehydration sachets — all of which can help manage mild symptoms at altitude. Ask for ibuprofeno, paracetamol, and suero oral. Many pharmacists in tourist areas speak English and can advise on dosing. Expect to pay between €3 and €8 for these over-the-counter products.

When You Need Emergency Care

Mild altitude sickness is uncomfortable but manageable. Severe altitude sickness can kill. The line between the two is not always obvious, which is why recognising red flags matters.

The single most effective treatment for severe altitude sickness is descent. Even dropping 300 to 500 metres can produce rapid improvement. If you are hiking in an organised group, make sure at least one person knows the fastest route down. On Teide, the cable car closes in the afternoon and in bad weather — plan your descent before you ascend. In the Pyrenees and Sierra Nevada, mountain rescue (rescate de montaña) can be reached through 112, Spain's universal emergency number. Do not wait to see if symptoms improve at altitude. If someone in your group develops confusion or breathing difficulty, start descending while you call for help.

How to Get Your Altitude Sickness Prescription in Spain

Acetazolamide needs to be started at least one day before you ascend. That means the time to get your prescription is before your hiking day, not at the trailhead. Leaving it to the last minute risks arriving at altitude without protection.

For tourists in Spain, getting a prescription can be frustrating. Public health centres (centros de salud) prioritise residents and may not see you quickly. Private clinics charge €80–150 for a consultation. Neither option is designed for a straightforward preventive prescription where you already know what you need.

PrescribeMe solves this. You complete a short medical questionnaire — including your planned altitude, ascent rate, and medical history — and a licensed Spanish physician reviews your case. If acetazolamide is appropriate, they issue a receta electrónica privada (a valid private electronic prescription) sent directly to your phone. You take it to any farmacia in Spain and walk out with your medication. The process takes as little as 15 minutes, works in English, and can be done from your hotel the night before your climb.