altitude sickness

Altitude sickness

Diamox (Acetazolamide) for altitude sickness, forced acclimatisation and altitude sleep disturbance. Medicine on prescription from NHS pharmacy.

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  • Medicine posted NHS UK pharmacy

Diamox (Acetazolamide) tablets: online prescription and delivery

Diamox is a brand name for acetazolamide 250mg tablets. The Diamox brand is no longer being sold in the UK (April 2015). We continue to use the name Diamox for acetazolamide tablets because this is the name people recognise. We supply only UK licensed acetazolamide from UK pharmacies.

Important Information

Please read the important information on this page regarding Diamox tablets for mountain sickness before ordering treatment.

Acetazolamide (Diamox) tablets for Altitude Sickness

Please do not order Diamox (acetazolamide) without reading and understanding this introduction page.

Altitude sickness introduction: printable format pdf.

Most trekkers and climbers do not need, and should not take, Diamox (acetazolamide) tablets.

Altitude problems are unlikely below 2,500 metres (8,000 feet).

Anybody can suffer from illness caused by altitude. Nobody is immune to it.

The best way to reduce the risk is to acclimatise and be prepared to descend.


Ascend slowly with overnight stops at regular intervals.

  • People planning to ascend over 3,000 metres (10,000 feet) should spend a night at an intermediate elevation below 3,000 metres before they start to ascend.
  • Above 3,000 metres ascend only 300-500 metres (1,000-1,500 feet) a day to each next new sleep height.
  • If more than 500 metres (1,500 feet) of ascent is required in the day, descend back to 500 metres to sleep (climb high, sleep low).
  • For every 1,000 metres (3,000 feet) of ascent stop for 2 nights sleep before going higher.

Symptoms of mild early acute mountain sickness

Stop ascending until feeling better.

  • Headache not relieved by paracetamol and drinking a litre of water (early symptom of acute mountain sickness)
  • Fatigue and weakness
  • Dizziness and light-headedness
  • Difficulty sleeping

Do not ascend if these symptoms develop. Stop until the symptoms resolve (usually 24-48 hrs) or descend. Descending will usually make the symptoms go more quickly.

Ascent can be continued when these symptoms subside, usually after 24-48 hrs.

  • Do not keep ascending
  • It helps to drink plenty
  • Avoid alcohol and sedatives

Emergencies requiring immediate descent

Two sets of symptoms requiring immediate descent:

  1. 1. Fluid on the lungs
    Showing up as struggling to breath, extreme fatigue, rattling breathing, coughing, blue or grey lips and fingernails, drowsiness, collapse, confusion and death. This condition is known as HAPE (High Altitude Pulmonary Oedema). The cardinal feature is extreme shortness of breath - being short of breath when everybody else has got their breath back.
  2. 2. Fluid on the brain
    Showing up as changes in behaviour, lethargy, and loss of coordination (unable to walk in a straight line). This can progress to coma and death. This condition is known as HACE (High Altitude Cerebral Oedema). The cardinal feature is cognitive impairment (inability to think straight and carry out normal tasks).

These two conditions are emergencies requiring immediate descent, even if this is in the night. The descent needs to be at least 500-1,000 metres (1,500-3,000 feet) and as soon as is possible. Delay can be fatal.

In addition to descent, treatment includes oxygen, steroids and hyperbarric oxygen (oxygen delivered in a high pressure chamber).

Notes about HACE and HAPE

  • Can come without any warning
  • Can develop rapidly over a period of hours
  • Often start at night, although can come on in the day
  • There may be no preceding symptoms or warning
  • Can affect people who have ascended previously to the same height without problems
  • Can affect people who have followed the guidelines for acclimatisation
  • Can affect people who are taking Diamox (acetazolamide)
  • Can affect fit and unfit people and indigenous people including porters
Acetazolamide Diamox tablets Acetazolamide (Diamox) 250mg Tablets

Consultation and supply on prescription from £27.00


Prices of treatment

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Cost of Diamox with consultation & if you already have a prescription.

About Acetazolamide (Diamox)

Diamox increases the amount of urine produced and changes the acidity of the blood. The net effect is to improve breathing and reduce fluid around the brain and in the lungs.

Acetazolamide is not licensed to prevent and treat altitude sickness, although it has long been used for this purpose.

POMAcetazolamide (Diamox) is a prescription only medicine.

Diamox side effects

Most people taking acetazolamide for short courses experiences no side effects.

Side effects reported include: a 'tingling' feeling in the fingers and toes, some loss of appetite, taste disturbance, flushing, thirst, headache, dizziness, fatigue, irritability, and depression.

Uses of Acetazolamide (Diamox)

1. In the mild acute mountain sickness (headache, fatigue, light headedness, difficulty with sleep) symptoms resolve more quickly with Diamox (acetazolamide). The symptoms usually go by themselves in around 24-48 hrs. This usually reduces to around 12-24 hrs with Diamox.

2. Taking Diamox will reduce the likelihood of altitude sickness in people who are forced to ascend without proper acclimatisation. Serious illness and even death are still possible. Diamox is not a substitute for acclimatisation.

3. Diamox improves the pattern of breathing during sleep at altitude and thus quality of sleep. During sleep at altitude the breathing pattern alters; rapid breaths are followed by prolonged pauses. This is not dangerous but tends to lead to poor sleep.

We do not recommend taking acetazolamide for people planning to undertake routine ascents. Most people who acclimatise properly do not need it. Taking Diamox (acetazolamide) can give a false sense of security.

Diamox dosage

1. For the treatment of mild early acute mountain sickness (headache, fatigue, light headedness, difficulty with sleep): Diamox 250mg (one tablet) twice daily until symptoms resolve, when planned ascent can be resumed.

2. Where rapid ascent without proper acclimatisation cannot be avoided: Diamox 250mg (one tablet) twice daily, started the day before ascent or as soon as possible after starting to ascend and continue for 2-3 days after final altitude is reached.

3. For disturbed breathing pattern during sleep: Diamox 125mg (half a tablet) twice daily. Continue until descent to an altitude where sleep is no longer a problem. Acetazolamide is not a sedative.


Stopping Diamox does not cause a rebound in symptoms. The symptoms will not be worse than they would have been if Diamox (acetazolamide) had not been taken in the first place.

Taking Diamox (acetazolamide) for early symptoms does not mean it is OK to keep ascending. Do not ascend until symptoms resolve completely, usually 24-48 hrs.

Diamox (acetazolamide) does not mask serious underlying symptoms. It treats the cause, not the symptoms. If a person feels better on Diamox (acetazolamide) it is because their condition has improved.

Take a trial dose of half a tablet 3-4 days before travel to check for possible adverse reactions.

Treat altitude with respect. Do not imagine that a strong person can simply battle through. People who climb and hike in high places have a reputation for pushing themselves. When it comes to altitude; planning ahead, taking one's time and responding to one's own body are virtues.

Further information

Talk to a site doctor via or 0117 2050198.

High altitude trekking and climbing and Mountain medicine from 'The Travel Doctor' website.

Diamox Acetazolamide Patient Information Leaflet Start

Prices for Diamox tablets plus online prescription fee

Diamox tabletsQuantityCost
Diamox (Acetazolamide) 250mg28 tablets£27.00
Diamox (Acetazolamide) 250mg56 tablets£49.50
Diamox (Acetazolamide) 250mg112 tablets£92.00
Prices with your own private paper prescription – please post to our pharmacy (details)
Diamox (Acetazolamide) 250mgper tablet£0.74

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