Diamox Dosing — The Complete Protocol
Acetazolamide (Diamox) has two distinct dosing protocols: lower doses for prevention (taken before and during ascent) and higher doses for treatment (taken when AMS develops). Most dosing confusion online mixes these up. Here's the evidence-based protocol used by the Wilderness Medical Society and mountain medicine guidelines.
The Dosing Table
| Purpose | Adult Dose | Timing | Duration |
|---|---|---|---|
| AMS prevention | 125mg twice daily | Start 1 day before ascent; continue through ascent | Until descent or 2 days at stable altitude |
| AMS treatment | 250mg twice daily | When symptoms develop | Until symptoms resolve + descent |
| Sleep (periodic breathing) | 125mg at bedtime | Optional add-on for altitude insomnia | While at altitude |
| Pediatric prevention | 2.5mg/kg/dose twice daily | Same as adult schedule | Same |
When to Take It
- Prevention: start the day BEFORE ascending — flying to Lukla tomorrow? Take your first dose today
- Stop when: descending or after 2–3 days at stable altitude without symptoms — you don't need it forever
- Treatment: if mild AMS develops, 250mg BID + rest at altitude; if symptoms worsen or don't improve in 24h — descend
- Diamox doesn't "fix" bad decisions — it buys acclimatization time, not a pass to ascend faster than you should
Side Effects — What to Expect
- Tingling hands/feet/lips — the most common effect, harmless, sometimes annoying — nearly universal
- Increased urination — it's a mild diuretic; expect more bathroom trips (logistically annoying on trek)
- Taste changes — carbonated drinks taste flat/metallic; beer especially
- Mild nausea possible — usually transient
- Sulfa allergy confusion — most "sulfa allergies" (antibiotic sulfonamides) don't cross-react with acetazolamide; discuss with us if uncertain
Who Shouldn't Take It
- Severe kidney disease — drug is renally cleared
- Severe liver disease
- True sulfonamide anaphylaxis (rare, different from common "sulfa allergy")
- Pregnancy — discuss with your doctor; limited data
- Hyponatremia/low potassium states
The Dosing Logic
Acetazolamide works by forcing bicarbonate excretion — acidifying the blood, which stimulates breathing and accelerates acclimatization. The prophylactic dose (125mg twice daily) achieves this without excessive side effects; higher doses are no more effective and cause more tingling and diuresis. The treatment dose (250mg twice daily) for established AMS is higher but still modest.
Dosing summary
- Prophylaxis: 125mg twice daily, start 1–2 days pre-ascent
- Treatment: 250mg twice daily for established AMS
- Duration: continue 2–3 days at highest sleeping elevation
- Pediatric: 2.5mg/kg/dose twice daily (max 125mg) — specialist guidance needed
- Take with food to reduce GI upset; expect increased urination
Who Benefits Most
The case for prophylaxis is strongest for: rapid-ascent itineraries (flying to Lukla, driving to high trailheads), prior AMS history, itineraries that force faster-than-recommended ascent rates, and anyone who wants to reduce risk rather than rely on symptoms. For gradual ascents with acclimatization days, the benefit is smaller — discuss your specific itinerary with a clinician before deciding.
The Prophylactic Dose
Prevention: 125mg twice daily starting 24 hours before ascent — the evidence-based dosing for AMS prophylaxis. Start before you go high, continue through the ascent period, stop when the acclimatization is complete or the descent begins. The dosing is the minimum effective — higher doses add side effects without better protection.
The Treatment Dose
Treatment of AMS: 250mg twice daily — the higher dose for the symptomatic illness, in addition to descent. For severe AMS or HACE, dexamethasone is the treatment — Diamox treats the mild-moderate cases. The dosing depends on the use: prevention is the low dose; treatment is the higher.
The Prevention Protocol
125mg twice daily starting 24 hours before ascent — the evidence-based dosing for AMS prophylaxis. Take the first dose before going to altitude, continue through the ascent period, stop when acclimatized or when descent begins. The twice-daily dosing (not once) maintains the blood level that prevents the symptoms.
The Side Effects
Common side effects: tingling (paresthesia — hands, feet, face), increased urination, altered taste (carbonated drinks taste flat), mild nausea. These are annoying but benign; they resolve on stopping. The side effects are the price of the protection; for those who cannot tolerate them, the non-pharmacological acclimatization is the alternative.
The Side Effect Management
Acetazolamide's side effects: the paresthesia (the tingling fingers/toes/lips — the carbonic anhydrase inhibition), the diuretic effect (the increased urination — the hydration management is important), the altered taste (the carbonated beverages taste flat — the carbonic anhydrase effect on the taste), and the sulfa-allergy consideration (the acetazolamide is a sulfonamide derivative — the allergy question).
The Trial Dose
The pre-trek trial — the dose taken at home before the trek to assess the tolerance — is recommended. The side effects that are intolerable at home will be intolerable on trek; the trial identifies the problem before the trek. For the traveler who has never taken it, the trial is the preparation that the trek may require.
The Pediatric Dosing
Pediatric Diamox dosing is weight-based (the 2.5mg/kg/dose twice daily) — the child's dose calculated by the weight. For the family trekking with the children, the pediatric dosing that is appropriate, not the adult dose scaled down arbitrarily.
The Timing Strategy
When to start: for the prophylaxis, start the day before the ascent (the drug level established); for the treatment, start when the symptoms appear. For the trek that ascends over days, the continuous dosing through the altitude exposure period.
The Prophylaxis Dose
Acetazolamide prophylaxis: 125-250mg twice daily, starting the day before the ascent. The dosing that is maintained during the ascent and for the 2-3 days after the target altitude is reached.
The Side Effects
Diamox side effects: the tingling in the hands/feet (the paresthesia that is the most common), the increased urination, the altered taste (the carbonated drinks that taste flat), and the rare serious reactions. For the side effects that are common, the awareness that they are expected.
The Duration
Acetazolamide duration — the prophylaxis that is continued for the 2-3 days at the target altitude, the treatment that is continued until the symptoms resolve. For the trek, the duration that is planned.
The Interaction
Diamox interactions — the diuretic that compounds (the electrolyte that is monitored), the high-dose aspirin (the toxicity risk), and the stimulant (the additive effect). For the medication list, the interaction that is checked.
The Duration
Diamox duration — the prophylaxis that continues for the ~2-3 days at the altitude or the duration of the risk. For the course that is completed, the altitude exposure that is covered.
The Side Effect
Diamox side effect — the paresthesia (the tingling that is common), the diuresis (the increased urination), and the taste alteration. For the side effect, the awareness that is maintained.
The Medication Cost
Acetazolamide cost — the ~$5-15 for the trek course (the cheap that is affordable). For the prophylaxis, the minimal that is the cost.
The Prescription
Diamox prescription — the clinic visit (the prescription that is provided) or the pharmacy that may dispense. For the access, the consultation that is used.
The Prescription Value
Diamox prescription — the consult that is included (the ~$40 visit that covers the dosing + the dispensing). For the correct use, the prescribed that is the safe.
The Generic
Acetazolamide generic — the ~$5-15/course (the cheap that is the standard). For the prophylaxis, the affordable that is stocked.
What is the standard Diamox (acetazolamide) dose for altitude?
Prophylaxis: 125mg twice daily starting 1–2 days before ascent, continuing 2–3 days at highest elevation. Treatment (for AMS): 250mg twice daily. The old higher doses (500mg+) are no more effective and cause more side effects. Pediatric dosing is weight-based — consult a clinician.
When should I start taking Diamox?
24–48 hours before arriving at altitude — the drug needs time to induce the metabolic changes (bicarbonate excretion, respiratory stimulation) that prevent AMS. Starting at the trailhead is too late; starting in Kathmandu is right. For rapid ascents (flying to Lukla), start the morning of the flight.
What are the side effects?
Common and benign: tingling in fingers/toes/lips (paresthesias — harmless), increased urination (it is a diuretic), altered taste of carbonated drinks. Rare but serious: allergic reaction (sulfa allergy cross-reactivity), kidney stones, severe dehydration. The tingling is the drug working — not a reason to stop.
Who should NOT take Diamox?
Sulfa allergy history (cross-reaction risk), severe liver or kidney disease, pregnancy (discuss with obstetrician), and anyone on medications that interact (high-dose aspirin, some anticonvulsants). A pre-trek consult reviews your specific situation — Diamox is not right for everyone.
Can I buy Diamox in Kathmandu?
Yes — widely available in pharmacies under the generic acetazolamide or brand names. Quality is reliable at established pharmacies. Buying in Kathmandu saves money, but ensure you have enough for the full trek — rural pharmacies do not stock it reliably.
