Cusco · Kilimanjaro · Everest Base Camp · the high Rockies
Acetazolamide is the CDC-backed way to blunt acute mountain sickness — prescribed online by a board-certified physician, at your pharmacy today. $49 flat.
Who needs it
CDC flags risk for anyone sleeping above ~8,000 ft — and strongly encourages prophylaxis above 11,000 ft or on fly-in arrivals like Cusco (3,339 m), where nearly half of travelers feel it in the first 48 hours.
How it works
125 mg twice daily, starting the day before ascent and through your first two days up high. It speeds the acclimatization your body would do anyway — think of it as a head start, not a shortcut.
What to expect
Tingly fingers and flat-tasting soda are normal and harmless. It never replaces sensible ascent — and we tell you exactly what "sensible" means for your route.
The prescription, precisely
Take 125 mg by mouth every 12 hours, beginning the day before ascent and continuing the first 2 days at altitude (longer if ascent continues). If body weight >100 kg: 250 mg twice daily.
Dosing per CDC Yellow Book 2026 — quantity set from your itinerary.
Risk is set by where you SLEEP on day 1–2 — CDC Yellow Book 2026 thresholds, the same ones our intake applies.
A mild sulfa-antibiotic allergy is NOT a bar
Per CDC, cross-reactivity between sulfa antibiotics and acetazolamide has not been reported. Tell the physician anyway — it goes in your chart.
Prior anaphylaxis to any medication
We hold the prescription for a physician decision rather than issuing along the standard path — deliberately more cautious than CDC requires.
Kidney disease
Dose and fit get a physician review per the FDA label.
Pregnant or breastfeeding
CDC advises pregnant travelers not to sleep above ~10,000 ft at all; the medication question is individualized by the physician.
The honest part
Acetazolamide reduces risk — it doesn’t abolish it. Even medicated, roughly 40% of fast Kilimanjaro climbers feel some symptoms. If symptoms worsen at altitude, descent is the treatment, and your plan says so plainly.
Yes — it’s the CDC Yellow Book’s recommended prophylaxis for acute mountain sickness. It works by speeding the acclimatization your body would do anyway. It reduces risk substantially; it does not make you immune, and descent remains the treatment if symptoms worsen.
The day before ascent, then through your first two days at altitude — longer if you keep climbing. 125 mg twice a day at standard dosing; your physician sets the exact quantity from your itinerary.
Two famous, harmless quirks: tingling in your fingers and toes, and carbonated drinks tasting flat. It’s also a mild diuretic, so hydrate. None of that is an allergy — it’s how the drug works.
Usually yes. CDC states cross-reactivity with sulfa antibiotics has not been reported, and a mild sulfa allergy is not a bar. If you’ve ever had true anaphylaxis to any medication, your case goes to the physician for an individual decision rather than through the standard path.
Gradual ascent is the foundation and nothing replaces it — the medication supplements it. The catch: some of the world’s best trips don’t offer a gradual option. You can’t fly into Cusco or La Paz slowly.
The $49 consult is HSA/FSA eligible and needs no insurance. Acetazolamide itself is a decades-old, inexpensive generic at U.S. pharmacies.
$49 flat · reviewed by Adam Z. Kawalek, MD · full refund if we can’t help