What Medicine Should I Take for High Altitude Illness? How to Use Diamox? Can Viagra Also Treat Altitude Sickness? A Complete Guide to Essential Climbing Medications and Emergency Procedures

Thu, 21 May 2026 18:30:00 +0800

One week before departure, you checked the gear checklist in your backpack three times, but you only have a vague understanding of those few pills in your medicine bag?

Taking them at the wrong time or using the wrong medication can be more dangerous than not bringing any at all.

Overview of Altitude Sickness Medications: Preventive vs. Treatment Drugs

Altitude sickness medications are divided into two main categories: Preventive and Treatment. Their roles are entirely different.

Function	Positioning	Timing of Use
Preventive Drugs	Accelerate the body’s adaptation to altitude	Start taking before departure
Treatment Drugs	Relieve symptoms that have already occurred	Use after symptoms appear

Preventive drugs are helping the body do its homework in advance, while treatment drugs are helping the body survive a crisis.

“Preventive drugs” and “treatment drugs” both cannot replace “descending,” which is the most fundamental solution.

Preventive Drug: Diamox (Acetazolamide / Diamox)

Diamox is currently the most widely used preventive medication for altitude sickness, and it is the only first-choice drug supported by sufficient research evidence.

Mechanism of Action

Diamox is a carbonic anhydrase inhibitor that acts on the kidneys:

Mechanism	Description
Inhibits carbonic anhydrase	Reduces the reabsorption of bicarbonate
Acidifies the blood	Stimulates the respiratory center
Deepens and accelerates breathing	Mimics the body’s acclimatization response at high altitudes

Simply put, Diamox allows your body to start adapting in advance, rather than scrambling only when oxygen is scarce.

Dosage and Administration

Item	Description
Dosage	For adults, 125 mg each time, once every 12 hours (250 mg daily)
Start Time	Start taking 1 day before departure
Duration	Continue taking until 2 to 3 days after arriving at the highest altitude, or when beginning to descend
Child Dosage	2.5 mg per kilogram of body weight, once every 12 hours

Common Side Effects

Side Effect	Description
Tingling in hands and feet	Most common, usually mild and tolerable
Frequent urination	Because the kidneys excrete more bicarbonate and water
Altered taste of carbonated beverages	Sodas and beers will taste weirdly metallic
Mild nausea	A small number of people may experience gastrointestinal discomfort

Contraindicated Groups

Contraindicated for those allergic to sulfonamide drugs
Those with severe renal or hepatic insufficiency
Patients with hypokalemia

It is recommended to try taking it once before departure to confirm that you do not have a severe allergic reaction to Diamox before bringing it up the mountain.

Alternative Preventive Drug: Dexamethasone

If you are allergic to sulfonamides and cannot use Diamox, Dexamethasone is an alternative option.

Item	Description
Type	Steroid (Glucocorticoid)
Dosage	4 mg every 6 hours
Action	Directly reduces brain swelling and inflammatory response
Limitation	Cannot be used long-term (steroid side effects) and does not accelerate altitude adaptation

Dexamethasone is “suppressing symptoms,” while Diamox is “accelerating adaptation.” Their mechanisms are completely different.

If Dexamethasone is used as a preventive, once you stop taking it, the body may experience rebound altitude sickness symptoms because it only temporarily masks the problem.

Medications for Treating High Altitude Cerebral Edema (HACE)

High Altitude Cerebral Edema is one of the most critical types of altitude sickness and can be fatal within 24 hours.

Drug	Dosage	Action
Dexamethasone	First dose 8 mg, then 4 mg every 6 hours	Rapidly reduces brain swelling, takes effect within hours

The role of Dexamethasone in treating HACE is “to buy time for descent,” temporarily restoring the patient’s consciousness and physical mobility.

Works better when paired with a Portable Altitude Chamber (PAC) or bottled oxygen

But the most important thing is still to descend immediately.

Medications for Treating High Altitude Pulmonary Edema (HAPE)

The fatality rate of High Altitude Pulmonary Edema is the highest among the three types of altitude sickness, and the core issue is excessively high pulmonary artery pressure.

Drug	Dosage	Action
Nifedipine (Adalat OROS)	30 mg every 8 hours (extended-release form)	Lowers pulmonary artery pressure, improves lung blood flow
Tadalafil (Cialis)	10 mg every 12 hours	Phosphodiesterase type 5 inhibitor (PDE5i), lowers pulmonary artery pressure
Sildenafil (Viagra)	50 mg every 8 hours	Also a PDE5i, lowers pressure by dilating pulmonary blood vessels

Yes, Viagra is indeed one of the medications used to treat High Altitude Pulmonary Edema.

It was originally developed for the purpose of lowering pulmonary artery pressure, and was only later discovered to have another more widely known “side effect” besides treating altitude sickness.

So if you see Viagra in a climbing medicine bag, don’t laugh; it could be a critical, life-saving drug.

Recommended Climbing Medicine Bag Checklist

Drug	Purpose	Carrying Suggestion
Diamox 125mg	Altitude sickness prevention	Prepare according to the number of itinerary days, start 1 day before departure
Dexamethasone 4mg	HACE emergency treatment	Carry at least 10 pills
Nifedipine 30mg ER	HAPE emergency treatment	Carry at least 6 pills
Panadol	Headache relief	Caffeine-free version is preferred
Anti-nausea drug	Nausea and vomiting	Such as Ondansetron

All medications must be obtained after physician evaluation before departure; do not purchase them on your own or use others’ medications.

It is recommended to visit a Travel Medicine Clinic for consultation.

Non-Drug Equipment: Oxygen and Altitude Chambers

Equipment	Description	Effect
Bottled Oxygen	Directly increases inhaled oxygen concentration	Maintains for a few hours, suitable for emergencies
Portable Altitude Chamber (PAC)	Manually pressurized sealed bag	Mimics a descent of 1,500 to 2,000 meters in altitude
Fingertip Pulse Oximeter	Monitors oxygen saturation (SpO₂)	Normal value is above 95%, below 90% at high altitude requires alertness

The process of using a Portable Altitude Chamber (PAC):

Place the patient inside the bag
Pressurize continuously with a foot pump
Maintain for 1 to 2 hours
The effect is roughly equivalent to descending 1,500 to 2,000 meters

The pressure bag is a lifesaver for buying time, but it cannot replace descent. Symptoms will return after the pressure treatment ends.

Emergency Situation Handling Flowchart

When a teammate or you experience severe altitude sickness symptoms, handle them in the following order:

Step 1: Assess Severity

Assessment Item	Mild	Severe (Requires Immediate Action)
Headache	Mild, relieved by pain relievers	Severe, pain relievers ineffective
Gait	Normal	Unsteady walking (Sign of cerebral edema)
Breathing	Slightly short of breath during activity	Short of breath even at rest (Sign of pulmonary edema)
Consciousness	Clear	Confused, lethargic, slow response

Step 2: Handling Mild Symptoms

Stop ascending
Rest and observe at the same altitude
Replenish water and keep warm
Take pain relievers to alleviate headache
If no improvement within 24 hours → proceed to Step 3

Step 3: Emergency Handling of Moderate to Severe Symptoms

Descend immediately by at least 500 to 1,000 meters
Give oxygen (if available)
Use a PAC (if immediate descent is impossible)
Cerebral edema → give Dexamethasone
Pulmonary edema → give Nifedipine
Do not let the patient act alone; at least one teammate must accompany them

Step 4: Follow-up Care

If symptoms improve after descending, continuous observation for 24 to 48 hours is still required
After symptoms disappear completely, consider resuming a slow ascent
Patients who have experienced HACE or HAPE are recommended to seek medical attention after descending

On the mountain, it is better to retreat one time too many than one time too few.

Travel Medicine Clinic: The Most Important Stop Before Departure

Almost all major hospitals in Taiwan have travel medicine clinics. Clinic services include:

Assessing your personal medical history and altitude sickness risk
Prescribing preventive medications based on itinerary altitude and days
Teaching you to recognize symptoms and emergency handling procedures
Providing vaccination recommendations (applicable to overseas trips)

Spending an afternoon at the clinic gains you peace of mind for the entire trip. This is the most worthwhile pre-trip investment.

Climbing on Health TLDRLSS