Diamox for Nepal Trekking: The Complete Guide to Acetazolamide at Altitude

Diamox (the brand name for Acetazolamide) is the most widely discussed medication in the Nepal trekking community, and for good reason. It is the only medication with strong clinical evidence for both the prevention and treatment of Acute Mountain Sickness (AMS), the most common altitude-related illness affecting trekkers in the Himalayas. Every year, thousands of trekkers heading to Everest Base Camp, Annapurna Circuit, Manaslu Circuit, and other high-altitude routes face the same question: should I take Diamox?

This guide provides comprehensive, evidence-based information about Diamox to help you have an informed discussion with your doctor. It covers how the drug works at a cellular level, who should consider taking it, dosage protocols for prevention and treatment, side effects (common and rare), when to start and stop, how to obtain it, natural alternatives, trek-specific recommendations, and the most persistent myths that circulate in trekking forums and lodge dining halls.

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What Is Diamox (Acetazolamide)?

Acetazolamide is a carbonic anhydrase inhibitor -- a class of medication originally developed to treat glaucoma (elevated eye pressure) in the 1950s. Researchers discovered that one of its effects -- making the blood slightly more acidic -- had a beneficial side effect at altitude: it stimulates deeper and faster breathing, which is precisely what the body needs when oxygen levels are reduced.

How It Works at the Cellular Level

At sea level, your body maintains a precise blood pH balance (around 7.40). When you ascend to altitude, reduced oxygen triggers hyperventilation (faster, deeper breathing) as the body attempts to take in more oxygen. However, hyperventilation blows off carbon dioxide, making the blood too alkaline (respiratory alkalosis), which actually suppresses the breathing drive. This creates a counterproductive cycle: your body needs to breathe faster but its own chemistry signals it to slow down.

Acetazolamide breaks this cycle:

1. It inhibits the enzyme carbonic anhydrase in the kidneys
2. This causes the kidneys to excrete bicarbonate (an alkaline substance) in the urine
3. Blood pH shifts slightly toward acidic (metabolic acidosis)
4. The respiratory center in the brain responds to the acidic blood by increasing breathing rate and depth
5. More oxygen enters the lungs and bloodstream
6. The body acclimatizes faster than it would naturally

In simpler terms: Diamox tricks your body into breathing more at altitude, mimicking the acclimatization process that would normally take days. It does not mask symptoms or make you immune to altitude sickness -- it accelerates the natural adaptation process.

What Diamox Actually Does

• Increases ventilation (breathing rate and depth), especially during sleep
• Reduces periodic breathing during sleep at altitude (the unsettling stop-start breathing pattern)
• Decreases fluid retention in the brain (reducing cerebral edema risk)
• Mildly increases urine output (diuretic effect)
• Speeds up the natural acclimatization process by 1-2 days

What Diamox Does NOT Do

• It does not cure altitude sickness once it develops severely
• It does not allow you to ascend faster than safe guidelines recommend
• It does not replace proper acclimatization (rest days, gradual ascent)
• It does not mask dangerous symptoms of HACE or HAPE
• It does not guarantee you will not get altitude sickness
• It does not make you invincible at altitude

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Who Should Consider Taking Diamox?

The decision to use Diamox prophylactically (preventively) depends on several individual factors. The Wilderness Medical Society and International Society for Mountain Medicine recommend considering prophylactic Diamox in the following situations:

Strong Candidates for Prophylactic Diamox

1. Previous history of Acute Mountain Sickness (AMS): If you have experienced AMS on prior high-altitude trips, you have a significantly higher risk of recurrence. Diamox reduces this risk by 40-85% depending on the study.

2. Rapid ascent profiles: If your itinerary gains altitude faster than the recommended 300-500m per day above 3,000m (common on some group treks with fixed schedules), prophylactic Diamox can help compensate.

3. First-time high-altitude trekkers going above 4,000m: If you have never been above 3,000-4,000m and have no idea how your body responds to altitude, Diamox provides a layer of protection during the uncertainty period.

4. Trekkers flying directly to high altitude: Flying to Lukla (2,860m) or driving to similarly high starting points means no gradual acclimatization from sea level.

5. People with a known slow acclimatization pattern: Some individuals acclimatize more slowly than average due to genetic factors.

Moderate Candidates (Discuss with Doctor)

• Trekkers going to 3,000-4,000m with adequate acclimatization time
• People with well-controlled asthma or mild respiratory conditions
• Trekkers who plan adequate rest days but want additional insurance
• Repeat Himalayan trekkers who acclimatize well but want extra safety margin

Not Typically Necessary

• Treks staying below 3,000m (Poon Hill from Pokhara, lower Annapurna sections)
• Trekkers with extensive high-altitude experience and known good acclimatization
• Very gradual ascent profiles with generous rest days
• Treks with overnight stops well below 3,000m

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Who Should NOT Take Diamox

Diamox is contraindicated (should not be used) in several specific medical situations:

Absolute Contraindications

1. Sulfonamide (sulfa) allergy: Acetazolamide is a sulfonamide derivative. If you have a documented allergy to sulfa drugs (sulfamethoxazole, etc.), you MUST NOT take Diamox. Cross-reactivity is well-documented and can cause severe allergic reactions including anaphylaxis.

2. Severe kidney disease or kidney failure: Diamox is processed by the kidneys. Impaired kidney function can cause dangerous drug accumulation.

3. Severe liver disease (hepatic insufficiency): Acetazolamide can worsen hepatic encephalopathy.

4. Adrenal gland failure (Addison's disease): The electrolyte changes from Diamox can be dangerous.

5. Severe electrolyte imbalances: Particularly low sodium or potassium levels.

Relative Contraindications (Discuss with Doctor)

• Mild kidney disease
• History of kidney stones (Diamox can increase stone risk)
• Currently taking other diuretics or potassium-lowering medications
• Pregnancy or breastfeeding (Category C -- potential fetal risk)
• Currently taking high-dose aspirin (risk of metabolic acidosis)
• Diabetes (may affect blood sugar levels)

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Dosage Guidelines: Prevention vs Treatment

Prophylactic (Preventive) Dose

Recommended dose: 125mg twice daily (morning and evening)

This is the standard prophylactic dose recommended by the Wilderness Medical Society based on multiple clinical trials. Studies show that 125mg twice daily is equally effective as higher doses for prevention while producing significantly fewer side effects.

Key points:

• 125mg twice daily provides the same preventive benefit as 250mg twice daily
• Lower dose means milder side effects (less tingling, less frequent urination)
• Some physicians prescribe 250mg twice daily for people with prior severe AMS, but this is not standard first-line prophylaxis
• Can also take a single 250mg sustained-release tablet once daily (equivalent efficacy, better compliance)

Treatment Dose

Recommended dose: 250mg twice daily (morning and evening)

If you develop symptoms of AMS despite prophylaxis (or were not taking Diamox), the treatment dose is higher. This should be combined with stopping ascent and potentially descending.

Key points:

• 250mg twice daily is standard treatment dose
• Begin at first symptoms of AMS (headache plus one other symptom: nausea, fatigue, dizziness, poor sleep)
• Continue until symptoms resolve AND you have had 24 hours symptom-free at the same altitude
• Treatment Diamox does NOT replace descent if symptoms are moderate or severe
• Never continue ascending while symptomatic, even on Diamox

Dosage Summary Table

| Purpose | Dose | Frequency | Duration | |---------|------|-----------|----------| | Prevention (standard) | 125mg | Twice daily | Start 24h before ascent above 3,000m; continue until 2-3 days at highest altitude or during descent | | Prevention (alternative) | 250mg sustained-release | Once daily | Same duration as standard | | Treatment (mild AMS) | 250mg | Twice daily | Until symptoms resolve + 24 hours symptom-free | | Treatment (moderate AMS) | 250mg | Twice daily | Combined with descent 500-1,000m |

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When to Start and Stop Taking Diamox

When to Start

Start Diamox 24 hours before ascending above 3,000m (9,800 ft).

For most Nepal treks, this means:

• Everest Base Camp: Start the day before flying to Lukla (2,860m) or while in Lukla on your first night
• Annapurna Circuit: Start when ascending above Chame/Pisang area (3,000-3,200m), typically day 4-5
• Manaslu Circuit: Start around Lho or Samagaon area (3,000-3,500m)
• Langtang Valley: Start when ascending above Lama Hotel toward Langtang village (3,000-3,400m)

Why 24 hours before? Acetazolamide takes 8-12 hours to reach peak effectiveness. Starting the day before ensures full protection when you arrive at altitude.

When to Stop

Continue Diamox until you have spent 2-3 days at your highest sleeping altitude or have begun descending.

For practical purposes on an EBC trek:

• Start: Day before Lukla flight or at Lukla
• Continue: Through ascent to Gorak Shep/EBC
• Stop: After 2 nights at Gorak Shep/Lobuche, or once descending below 4,000m
• Typical duration: 10-12 days for a standard 14-day EBC trek

Stopping abruptly is fine. Unlike some medications, Diamox has no withdrawal effects. You can stop taking it without tapering.

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Side Effects: What to Expect

Common Side Effects (Experienced by Most Users)

These are normal, expected, and generally not concerning:

1. Tingling in Fingers, Toes, and Lips (Paresthesia)

• Experienced by 50-80% of users
• Described as "pins and needles" or "fizzy" sensation
• Most noticeable in the first 2-3 days; often diminishes
• Not dangerous; purely sensory
• A useful confirmation that the drug is working

2. Increased Urination (Diuresis)

• Diamox is a mild diuretic; expect more frequent urination
• Particularly noticeable at night (plan for midnight bathroom trips)
• Important: compensate by drinking MORE water, not less
• This diuretic effect is part of how the drug helps acclimatization

3. Altered Taste of Carbonated Drinks

• Beer, soda, and sparkling water taste flat, metallic, or unpleasant
• This is nearly universal and begins within hours of first dose
• Caused by Diamox's effect on carbonic anhydrase in taste buds
• Non-carbonated drinks taste normal
• Returns to normal within 2-3 days of stopping

4. Mild Nausea or Loss of Appetite

• Some users experience reduced appetite, particularly in the first few days
• Usually mild and manageable
• Can be reduced by taking Diamox with food

5. Drowsiness or Fatigue

• Mild tiredness possible, especially in first few days
• Usually resolves as body adjusts
• Difficult to distinguish from normal altitude fatigue

Less Common Side Effects

• Mild diarrhea (5-10% of users)
• Light sensitivity or blurred vision (rare)
• Rash (uncommon; discontinue if it develops)
• Confusion or disorientation (rare; difficult to distinguish from AMS -- see doctor)

Serious Side Effects (Seek Immediate Medical Help)

These are rare but require urgent attention:

• Severe allergic reaction: Hives, facial swelling, difficulty breathing (especially if sulfa-sensitive)
• Severe skin reactions: Stevens-Johnson syndrome (extremely rare but life-threatening; blistering skin/mucous membranes)
• Blood disorders: Easy bruising, unusual bleeding (very rare with short-term use)
• Kidney stones: Increased risk with prolonged use; less relevant for 2-week treks
• Significant vision changes: Beyond mild light sensitivity

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Getting Diamox: Before and During Your Trip

In Your Home Country (Before Travel)

In most Western countries (USA, UK, EU, Canada, Australia), Diamox requires a prescription. Visit your doctor or a travel medicine clinic:

• Explain your trekking plans, including maximum altitude and duration
• Request a prescription for Acetazolamide 125mg tablets (enough for your trek duration plus extras)
• Discuss your medical history, allergies, and current medications
• Ask about a test dose (see below)

Cost: $10-30 for generic acetazolamide with insurance; $30-60 without insurance

In Nepal (Over-the-Counter)

Diamox is available without prescription at pharmacies throughout Kathmandu and Pokhara:

• Where to buy: Any pharmacy in Thamel (Kathmandu) or Lakeside (Pokhara)
• Brand names in Nepal: Diamox, Acmox, Acetamide, or generic "Acetazolamide"
• Cost: NPR 200-500 for a trekking course ($2-5)
• Available doses: 250mg tablets (split in half for 125mg prophylactic dose)

Pharmacies to try in Kathmandu:

• Pharmacies along Thamel Marg
• New Road area pharmacies
• CIWEC Hospital pharmacy (higher confidence in drug quality)

Important: While convenient, buying medication in Nepal means you skip the critical doctor consultation. If possible, obtain Diamox at home where your doctor can review your full medical history.

On the Trail

Some larger villages along trekking routes have basic pharmacies:

• Namche Bazaar (Everest): Several pharmacies carry Diamox
• Manang (Annapurna Circuit): Small pharmacy available
• HRA Clinics (Pheriche, Manang): Medical professionals can advise and sometimes provide medication

However, do NOT rely on trail availability. Carry your full supply from Kathmandu or home.

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The Test Dose: Try Before You Trek

Strongly recommended: Take a test dose of Diamox at home 2-4 weeks before your trek.

Why Test?

• Identifies allergic reactions in a safe environment (near a hospital, not on a mountain)
• Allows you to experience the common side effects (tingling, taste changes) without the stress of being at altitude
• Confirms you tolerate the drug before committing to using it during your trek
• Provides peace of mind

How to Test

1. Take 125mg (or half a 250mg tablet) in the morning
2. Take another 125mg in the evening
3. Continue for 2-3 days
4. Note all side effects
5. Try drinking a carbonated beverage to experience the taste change
6. Observe any allergic reactions (rash, swelling, breathing difficulty)

What to Expect During the Test

• Tingling in extremities within 2-4 hours (normal)
• Increased urination within 2-6 hours (normal)
• Carbonated drinks taste flat or metallic (normal)
• Mild nausea possible (usually passes)

When to Stop the Test and Consult Your Doctor

• Any skin rash or hives
• Difficulty breathing or swelling
• Severe nausea or vomiting
• Significant vision changes
• Any symptom that concerns you

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Natural Alternatives to Diamox

For trekkers who cannot take Diamox (sulfa allergy, personal preference) or prefer natural approaches, several alternatives exist, though none have as strong an evidence base.

Evidence-Based Alternatives

1. Proper Acclimatization (The Gold Standard)

• Ascend no more than 300-500m per sleeping altitude per day above 3,000m
• Take a rest day every 1,000m of altitude gained
• "Climb high, sleep low" when possible
• This is the most effective strategy regardless of whether you take Diamox
• Read our complete acclimatization guide

2. Dexamethasone (Prescription Alternative)

• A corticosteroid that reduces brain swelling at altitude
• Used for treatment of moderate-severe AMS and HACE
• NOT recommended for routine prophylaxis due to significant side effects
• Reserved for emergencies or people with sulfa allergy who need pharmacological protection
• Must be prescribed by a doctor

3. Nifedipine (For HAPE Prevention)

• A calcium channel blocker that reduces pulmonary artery pressure
• Used specifically for HAPE prevention in people with prior HAPE history
• Not effective for general AMS prevention
• Prescription only

Popular Natural Remedies (Limited Evidence)

4. Ginkgo Biloba

• Some studies show modest benefit for AMS prevention
• Results are inconsistent across clinical trials
• Dose studied: 120mg twice daily, starting 5 days before ascent
• Quality and standardization of supplements varies widely
• The Wilderness Medical Society gives this a "weak recommendation"

5. Garlic

• Traditional Sherpa remedy for altitude symptoms
• No clinical evidence of effectiveness
• Harmless to try alongside proper acclimatization
• Available fresh along trekking routes

6. Coca Leaves/Tea

• Traditional in Andean altitude regions (South America)
• Not traditionally used in Nepal and not locally available
• Limited clinical evidence for effectiveness
• Illegal in many countries

The Bottom Line on Alternatives

No natural alternative has the clinical evidence that acetazolamide has. If you cannot take Diamox, the most important strategy is conservative acclimatization: slow ascent, adequate rest days, and immediate response to any symptoms. Discuss dexamethasone as an emergency medication with your doctor if you have a sulfa allergy.

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Diamox Myths vs Facts: Setting the Record Straight

Trekking forums, lodge dining halls, and fellow trekkers are full of Diamox opinions. Many are wrong. Here are the most persistent myths corrected with evidence-based facts.

Myth 1: "Diamox masks altitude sickness symptoms"

FACT: This is the most dangerous myth. Diamox does NOT mask symptoms. It accelerates acclimatization, reducing the likelihood of symptoms developing. The side effects of Diamox (tingling, taste changes, urination) are completely different from AMS symptoms (headache, nausea, dizziness). If you develop AMS while on Diamox, you will still feel it clearly. The Wilderness Medical Society specifically states that Diamox "does not mask the symptoms of AMS."

Myth 2: "Taking Diamox means you don't need to acclimatize"

FACT: Absolutely false. Diamox aids acclimatization; it does not replace it. You must still follow proper ascent rates, take rest days, and respond to symptoms even when taking Diamox. Think of it as a supplement to proper acclimatization, not a substitute.

Myth 3: "Only weak or unfit people need Diamox"

FACT: Altitude sickness has NO correlation with fitness level. Elite athletes get AMS at the same rate as sedentary individuals. Many Ironman athletes and marathon runners have been evacuated from EBC with severe AMS. Taking Diamox is a smart medical decision, not a sign of weakness. The Himalayan Rescue Association specifically debunks this myth.

Myth 4: "Diamox is just a band-aid -- you should acclimatize naturally"

FACT: Diamox IS natural acclimatization -- it just accelerates the process. It does not create an artificial state; it speeds up the same physiological changes your body would make on its own (increased ventilation, bicarbonate excretion). The endpoint is the same as natural acclimatization.

Myth 5: "You should not take Diamox unless you are already sick"

FACT: Diamox is most effective when taken BEFORE symptoms appear (prophylactically). Waiting until you are sick requires a higher dose and is less effective than prevention. This myth may cause people to suffer needlessly.

Myth 6: "Diamox causes severe dehydration"

FACT: Diamox is a mild diuretic. It increases urination modestly, which is easily compensated by drinking an extra 0.5-1 liter of water daily. It does not cause the severe dehydration associated with stronger diuretics. The key is simply to drink more water, which you should already be doing at altitude (3-4 liters/day recommended).

Myth 7: "You can buy fake Diamox in Nepal"

FACT: While counterfeit medications exist in some developing countries, acetazolamide purchased from reputable pharmacies in Kathmandu (especially those near tourist areas or hospitals) is generally legitimate generic medication manufactured by licensed pharmaceutical companies. That said, buying from your home country with a prescription provides the highest quality assurance.

Myth 8: "Diamox makes you unable to drink beer on trek"

FACT: Partially true but misleading. Diamox alters the taste of carbonated drinks (beer, soda) -- they taste flat or metallic. You CAN still drink beer; it just will not taste as good. More importantly, alcohol at altitude is generally inadvisable regardless of Diamox, as it impairs acclimatization, causes dehydration, and disrupts sleep.

Myth 9: "Once you start Diamox, you cannot stop until you descend"

FACT: You can stop Diamox at any time without withdrawal effects. The recommended protocol is to continue until 2-3 days at your highest sleeping altitude or until you begin descending, but stopping abruptly is safe.

Myth 10: "Diamox is dangerous and has severe side effects"

FACT: At the doses used for altitude prophylaxis (125mg twice daily for 1-2 weeks), Diamox has an excellent safety profile. Side effects are common but mild and temporary. Serious adverse effects are rare and almost always associated with long-term use or in people with contraindications (sulfa allergy, kidney disease). The risk-benefit ratio strongly favors Diamox use for trekkers going above 3,000m.

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Trek-Specific Diamox Recommendations

Everest Base Camp (Max: 5,364m / 5,643m Kala Patthar)

Recommendation: Strongly consider Diamox prophylaxis

The EBC trek ascends from Lukla (2,860m) to Gorak Shep (5,164m) over 8-10 trekking days. This is a significant altitude gain, and the standard itinerary includes only 2 acclimatization days (Namche and Dingboche). AMS incidence on the EBC route is 50-85% without prophylaxis.

• Start Diamox the day before the Lukla flight
• Continue through the highest nights at Gorak Shep/Lobuche
• Especially valuable for the rapid initial gain (Lukla to Namche, 2,860 to 3,440m in 2 days)

Annapurna Base Camp (Max: 4,130m)

Recommendation: Optional but beneficial for first-timers

ABC's maximum altitude is moderate, and the ascent profile is generally gradual. Many experienced trekkers complete ABC without Diamox. However, first-time altitude trekkers and those with prior AMS benefit from prophylaxis above Deurali (3,200m).

Annapurna Circuit / Thorong La (Max: 5,416m)

Recommendation: Consider Diamox, especially for Thorong La day

The circuit's gradual ascent through the Marsyangdi Valley provides good natural acclimatization, but the final push to Thorong La (5,416m) is a major altitude challenge. Consider starting Diamox 1-2 days before Thorong La crossing.

Manaslu Circuit / Larkya La (Max: 5,160m)

Recommendation: Consider Diamox for Larkya La approach

Similar to Annapurna Circuit -- good natural acclimatization on approach but a significant altitude gain for the Larkya La pass day. Diamox beneficial from Samagaon (3,530m) onward.

Poon Hill (Max: 3,210m)

Recommendation: Generally not needed

Poon Hill's maximum altitude is modest, and the ascent from Pokhara is gradual. Diamox is typically unnecessary unless you have a history of AMS at low altitudes.

Langtang Valley (Max: 3,870m / 4,984m Tserko Ri)

Recommendation: Generally not needed for valley; consider for Tserko Ri

The Langtang Valley main route tops out at 3,870m (Kyanjin Gompa), which most trekkers handle without prophylaxis. If ascending Tserko Ri (4,984m), Diamox provides useful protection for the day hike.

Three Passes Trek (Max: 5,535m Kongma La)

Recommendation: Strongly recommended

Three high passes in rapid succession with limited acclimatization time between them. This is one of Nepal's most altitude-demanding standard treks. Diamox is strongly recommended for most trekkers.

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What Diamox Does NOT Protect Against

Understanding Diamox's limitations is as important as understanding its benefits.

HACE (High Altitude Cerebral Edema)

While Diamox reduces AMS risk (and HACE is the extreme progression of AMS), Diamox alone does NOT reliably prevent HACE once severe symptoms develop. HACE requires immediate descent and dexamethasone. See our altitude sickness signs and turnaround rules guide.

HAPE (High Altitude Pulmonary Edema)

Diamox has minimal effect on HAPE, which involves fluid in the lungs rather than the brain. HAPE prevention requires nifedipine (for those with prior HAPE) or, most importantly, proper ascent rates. HAPE requires immediate descent and supplemental oxygen.

Poor Decision-Making at Altitude

No drug compensates for ignoring symptoms, skipping rest days, or pushing through when your body signals distress. The most common cause of altitude fatalities is continuing to ascend despite warning symptoms. Diamox does not change human judgment.

Effects of Altitude on Pre-Existing Conditions

Diamox does not protect against the effects of altitude on heart conditions, lung disease, or other pre-existing medical conditions. Trekkers with significant medical conditions need comprehensive medical clearance beyond Diamox discussions.

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Frequently Asked Questions

Should I take Diamox for Everest Base Camp?

For most first-time EBC trekkers, the answer is yes, prophylactic Diamox is recommended. The EBC trek involves significant altitude gain (sea level to 5,364m or 5,643m including Kala Patthar), and AMS incidence without prophylaxis is 50-85%. Discuss with your doctor, and strongly consider a test dose at home first.

Can I drink alcohol while taking Diamox?

Technically yes, but it is inadvisable. Diamox alters the taste of carbonated drinks (beer will taste flat), and alcohol at altitude is independently harmful: it impairs acclimatization, causes dehydration, disrupts sleep quality, and increases AMS risk. The Himalayan Rescue Association advises limiting alcohol above 3,000m regardless of Diamox use.

Does Diamox affect physical performance or fitness?

Diamox does not significantly impair physical performance. Some trekkers report mild fatigue in the first 1-2 days, but this typically resolves. The increased breathing rate from Diamox actually improves oxygen delivery, which can enhance performance at altitude compared to no treatment.

Can I take Diamox with other medications?

Diamox interacts with several medications. Key interactions include: high-dose aspirin (increased risk of metabolic acidosis), lithium (altered lithium levels), certain anti-seizure medications, and other diuretics. Always provide your doctor with a complete list of current medications before starting Diamox.

How long does it take for Diamox to work?

Diamox reaches peak blood levels in 2-4 hours and achieves full physiological effect in 8-12 hours. This is why starting 24 hours before ascending above 3,000m is recommended. The acclimatization benefit builds over the first 24-48 hours of use.

Can I take half the recommended dose to reduce side effects?

The standard prophylactic dose (125mg twice daily) is already the minimum effective dose established in clinical trials. Going lower is not recommended as it may not provide adequate protection. If 125mg twice daily causes intolerable side effects, discuss alternatives with your doctor rather than reducing the dose.

What if I forget to take a dose?

Take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular schedule. Do not double up. Missing one dose will not eliminate protection, but consistent dosing provides the best results.

Is it safe to take Diamox for 2-3 weeks?

Yes. At the doses used for altitude prophylaxis, 2-3 weeks of use is well within safe limits. Diamox has been prescribed for months or years for conditions like glaucoma with acceptable safety profiles. The risks associated with altitude sickness far outweigh the minimal risks of short-term acetazolamide use.

Can children take Diamox?

Yes, but at adjusted doses based on weight (2.5mg/kg/dose twice daily). Children trekking in Nepal at altitude should have a pediatrician's guidance for dosing. See our trekking with families guide for more information.

Can I buy Diamox at the airport in Kathmandu?

Tribhuvan International Airport does not have pharmacies in the arrivals area. You will need to purchase Diamox from a pharmacy in Kathmandu (Thamel area has many) or Pokhara. Plan to buy it at least 24 hours before starting your trek to begin prophylaxis on schedule.

Should I take Diamox if I have been to altitude before without problems?

If you have previously tolerated similar altitudes (above 4,000m) without AMS, your risk is lower. However, past success does not guarantee future immunity -- many experienced trekkers develop AMS on subsequent trips. Diamox is still a reasonable precaution, especially for treks above 5,000m. Discuss your history with your doctor.

Does Diamox work the same for everyone?

No. Individual responses vary. Most people experience clear benefit with tolerable side effects, but a small percentage may not tolerate the side effects or may still develop AMS despite prophylaxis. Genetic differences in carbonic anhydrase enzymes may explain variable responses. This is another reason the test dose at home is valuable.

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Summary: Making Your Diamox Decision

The decision to use Diamox should involve three steps:

1. Consult your doctor: Share your trekking plans, medical history, allergies, and current medications. Ask specifically about acetazolamide for altitude prophylaxis.

2. Test it at home: If your doctor prescribes Diamox, do a 2-3 day test at home to confirm you tolerate it and identify any allergic reactions.

3. Use it properly on trek: If you decide to take it, follow the dosage protocol (125mg twice daily for prevention), start 24 hours before ascending above 3,000m, and continue until you have spent 2-3 days at your highest sleeping altitude or have started descending.

Remember: Diamox is a valuable tool, but it is ONE tool in your altitude safety toolkit. Proper acclimatization (gradual ascent, rest days, hydration), symptom awareness, and willingness to descend when needed are equally or more important. No medication replaces good judgment in the mountains.

For comprehensive altitude sickness information, see our altitude sickness prevention and treatment guide and altitude sickness signs and turnaround rules.

For travel insurance that covers altitude emergencies, see our Nepal trekking insurance guide.