Hypertension and high-altitude trekking is an important topic affecting ~30% of the 50+ population. Good news: controlled hypertension does NOT exclude expeditions to 5500 m. Bad news: altitude raises blood pressure by 10–20 mmHg, some antihypertensives lose efficacy, and some increase HAPE risk. This article: physiology, safe and risky medications, field BP monitoring protocol, when to cancel the expedition.
In a nutshell — hypertension and altitude
- Controlled hypertension (<140/90 on medication) — compatible with trekking to 5500 m
- Altitude raises BP by 10–20 mmHg via sympathetic activation and endothelin
- Safe medications: ACE inhibitors (ramipril, enalapril), ARBs (losartan), long-acting nifedipine — bonus: HAPE prophylaxis
- Risky medications: beta-blockers (reduce acclimatization capacity), diuretics (dehydration risk)
- Monitoring: wrist BP cuff ($25–40), measurements 2× daily
- Contraindications: poorly controlled hypertension, values >180/110, recent MI, heart failure
How altitude affects blood pressure
Mechanism — sympathetic activation
Hypoxia activates carotid body chemoreceptors, which stimulate the sympathetic nervous system. Effect: increased catecholamine release (adrenaline, noradrenaline), vasoconstriction, accelerated heart rate. Systolic BP typically rises 10–20 mmHg, diastolic 5–10 mmHg. The effect persists for weeks to months at altitude — without full adaptation like ventilation.
Endothelin-1 and vasoconstriction
Hypoxia stimulates endothelin-1 release from endothelial cells — a potent peripheral vasoconstrictor. The same mechanism underlies HAPE (pulmonary artery constriction) and peripheral arteriole constriction in fingers/ears in cold. In a hypertensive patient this is an additional pathophysiological element increasing risk.
Polycythemia — blood viscosity
After 2–4 weeks above 4000 m, hematocrit rises from 42% to 55–65%. Better oxygenation, but blood becomes viscous — increasing peripheral resistance and BP. This is the main reason why on long expeditions (Everest, Aconcagua) hypertension can worsen even on appropriate medication.
Antihypertensives — which to choose for expedition
ACE inhibitors (recommended)
- Ramipril 5–10 mg/day, enalapril 10–20 mg/day, lisinopril 10–20 mg/day
- Mechanism: block RAAS, vasodilate, don’t affect acclimatization
- Additional benefits: cardioprotection, anti-inflammatory effect
- Side effects: dry cough (5–15%), hyperkalemia (rare)
- Note: if you’re on an ACEi — continue unchanged
ARBs (sartans, alternative to ACEi)
- Losartan 50–100 mg/day, telmisartan 40–80 mg/day, valsartan 80–160 mg/day
- Advantages: like ACEi but no cough; cardioprotection, nephroprotection
- Good for expeditions — often better tolerated than ACEi during prolonged exertion
Long-acting nifedipine (double-duty)
- Nifedipine XL/Retard 30–60 mg/day or amlodipine 5–10 mg/day
- Double benefit: lowers systemic BP AND is HAPE prophylaxis (reduces pulmonary vascular resistance)
- Ideal choice for hypertensive patient planning expedition >4000 m
- Side effects: ankle edema, headaches at treatment initiation
Beta-blockers (with caution)
- Bisoprolol, metoprolol, nebivolol — most commonly used
- Problem: reduce maximum exertional heart rate (HRmax), impairing altitude exertion tolerance
- Mechanism: beta-blockers block compensatory tachycardia, body can’t increase O₂ delivery proportionally to exertion
- Decision: if beta-blocker is for cardiological indication (post-MI, atrial fibrillation) — continue and limit expeditions to 3500–4000 m; if only for BP — switch to ACEi/ARB 2 months before expedition
Diuretics (very cautious)
- Hydrochlorothiazide, indapamide, furosemide
- Problem: increase dehydration risk (hydration is already a challenge on expedition)
- Risk: hypokalemia, electrolyte disturbances, dehydration + increased blood viscosity (hematocrit)
- Decision: switch to ACEi/ARB before expedition; if necessary — reduce dose 50%, monitor urine (color)
Blood pressure monitoring in the field
- Wrist BP cuff (Omron, Microlife) — $25–40, light (150 g), runs on 2× AAA
- Protocol: morning on waking before exertion and evening at camp, 2 measurements 2 min apart, take median
- Target on expedition: <150/95 (less strict than at sea level)
- Red flag: >180/110, headaches + dizziness, visual disturbances — signal of hypertensive crisis, evacuation
- False elevation: cold, stress, exertion — wait 10 min in warm tent before measurement
When NOT to go high altitude
- Poorly controlled hypertension (>160/100 on current medication)
- Myocardial infarction within 6 months
- Heart failure (EF <50%, NYHA II+)
- Uncontrolled atrial fibrillation with rapid ventricular response
- Hypertensive retinopathy grade III/IV
- Kidney failure (GFR <60) — risk of deterioration
In these cases: cardiology consultation, expeditions to 2500–3000 m, avoid >4000 m.
Frequently asked questions
Can I climb Kilimanjaro on a beta-blocker?
Yes, with caveats. Kilimanjaro 5895 m on beta-blocker is possible, but expect: 1) lower exertion tolerance (HRmax reduced 20-30 bpm); 2) slower acclimatization (less compensatory ventilation); 3) more fatigue. Recommendation: switch to ACEi/ARB 2 months before expedition IF beta-blocker is only for BP. If post-MI or atrial fibrillation – continue beta-blocker, but extend Kilimanjaro schedule by 1-2 days (e.g. 8 days instead of 6).
Does amlodipine (calcium channel blocker) help with HAPE?
Yes, at least theoretically. Nifedipine SL/retard 30 mg is standard HAPE prophylaxis (Bärtsch 2005) – pulmonary artery vasodilation. Amlodipine 5-10 mg/day acts similarly, though fewer studies in this indication. If amlodipine is your BP medication – continue, you get bonus HAPE prophylaxis. Absolutely: don’t stop nifedipine/amlodipine before expedition. If your doctor wants to switch you 3 months before expedition >4000 m – ask to keep amlodipine or add nifedipine as HAPE prophylaxis.
I have hypertension and take HCT. Can I do EBC?
Yes, but swap HCT. Hydrochlorothiazide is a diuretic increasing water and electrolyte loss. On expedition: 1) dehydration is already a problem (dry air, intense breathing, difficult water access); 2) hypokalemia further weakens muscles; 3) blood viscosity rises via polycythemia – additional dehydration worsens rheology. Recommendation: cardiology consultation 3 months pre-expedition, switch HCT to losartan 50 mg or ramipril 5 mg. EBC is safe on that medication.
How much does BP rise at 5000 m?
Typically systolic 10-20 mmHg, diastolic 5-10 mmHg above sea-level values. Mechanism: sympathetic activation by hypoxia (carotid body chemoreceptors), elevated catecholamines, vasoconstriction (endothelin-1). Effect persists throughout altitude stay – does NOT adapt like ventilation. In a well-controlled hypertensive patient this means targeting ~140/90 instead of 125/80 sea level. Hence target <150/95 on expedition is realistic.
I have hypertensive crisis during trek – what to do?
Crisis (BP >180/110 + symptoms: headaches, dizziness, visual disturbances, dyspnea, chest pain) is life-threatening. Protocol: 1) Lie down immediately, elevate legs, breathe calmly. 2) If you have captopril SL (Capoten 25 mg) – sublingual, effect in 15-30 min. 3) Oxygen if available. 4) Satellite/heli evacuation – this is NOT a walk-out situation. 5) Don’t give furosemide as first choice (too aggressive). In hypertensive patient’s kit always: captopril SL 25 mg (3-4 tablets).
References
- Parati G, Revera M, Giuliano A, et al. Effects of acetazolamide on central blood pressure, peripheral blood pressure, and arterial distensibility at acute high altitude exposure. Eur Heart J. 2013;34(10):759–766.
- Mingji C, Onakpoya IJ, Perera R, et al. Relationship between altitude and the prevalence of hypertension. Heart. 2015;101(13):1054–1060.
- Wilderness Medical Society 2019 Guidelines.
- ESC/ESH 2023 Guidelines for the management of arterial hypertension.
Note: A patient with hypertension requires cardiology consultation 3 months before a high-altitude expedition, possible medication changes and continuous monitoring. This article is informational. Emergency numbers: 112, TOPR +48 601 100 300.