Acetazolamide 250mg Tablets

Acetazolamide 250mg tablets (also known as Diamox) are available to buy from The Independent Pharmacy Online Doctor service, following a free consultation, to help to prevent and treat altitude sickness. To find out more about acne and see all the available treatments, see our Altitude Sickness page.

What does Acetazolamide treat?

Acetazolamide has several applications (such as glaucoma, fluid buildup, and epilepsy) but is widely prescribed 'off-label' to prevent or reduce the symptoms of altitude sickness. Acetazolamide can actively reduce nausea, dizziness, headache and shortness of breath associated with rapid ascents (usually anything above 10,000 feet or 3,048 metres).

Acetazolamide 'off-label'

The prescription is ‘off-label’ because Acetazolamide was initially licensed to treat conditions other than altitude sickness, so its original instructions will not match your condition. 'Off label' means that the medicine is being used to treat a condition other than those that it was initially licensed to treat. This means that there is less established data regarding the effectiveness of this treatment for the condition for which it is prescribed and means that the instructions contained in the product information leaflet will not match the condition you are treating.

Click here to read studies on the effectiveness of Acetazolamide in treating Altitude Sickness 'off label'. You should always follow the instructions on the dispensing label on your medicine and contact us if you have any questions.

What does Acetazolamide (Diamox) do?

Acetazolamide 250mg tablets works to treat altitude sickness by increasing the amount of urine produced, consequently altering the acidity of the blood. This leads to a reduction in fluid in the lungs and around the brain. The result is improved breathing and relief from the symptoms of altitude sickness.

How long does Acetazolamide take to work?

How long it takes for Acetazolamide to take effect depends on the person, but it’s recommended that you start taking it a day or two before you expect to need it, and continue using it during the ascent and for two or three days after you’ve reached the peak of your trip.

Effect on recovery rate

Without medication, the symptoms of altitude sickness will usually subside in around 24-48 hours if the proper procedures are followed. Taking Acetazolamide 250mg tablets has been shown to cut recovery time in half (between 12-24 hours).

No substitute for acclimatisation

Taking Acetazolamide will help to decrease the likelihood of experiencing altitude sickness in people who are forced to ascend without proper acclimatisation. However, Acetazolamide should not be seen as a substitute for acclimatisation. Rapid ascents are dangerous with or without Acetazolamide usage.

Breathing improvement & regulation

Sleeping at altitude alters a person’s breathing patterns. It is usually characterised as short, rapid breaths followed by prolonged pauses. This is quite normal and is not considered dangerous. However, it can lead to a poor quality of sleep. Taking Acetazolamide tablets will help improve this pattern of breathing, resulting in a better quality of sleep.

Height risk of altitude sickness

Symptoms are unlikely to develop at heights below 2,500 metres (8,000 feet), so most trekkers, climbers or hikers shouldn’t need to take Acetazolamide. That said, anyone can suffer from altitude sickness - even if they are very fit, and it can occur at lesser heights in very rare cases.

How to reduce the risk of altitude sickness

You can minimise the risk of experiencing altitude sickness by following established protocols:

• Acclimatise by ascending slowly with overnight stops at regular intervals.
• If you are planning to climb over 3,000 metres (10,000 feet), spend a night at an intermediate elevation below 3,000 metres before starting your final ascent
• When over 3,000 metres, limit your rate of ascension to 300-500 metres (1,000-1,500 feet) per day, stopping to sleep each night
• After every 1,000 metres (3,000 feet) of ascent, rest for a couple of nights before climbing any higher
• If you climb more than 500 metres (1,500 feet) during one day, descend 500 metres before sleeping

Symptoms of mild early acute mountain sickness

If you experience any of the following symptoms, stop ascending until you feel better:

• A headache that won’t be relieved by taking Paracetamol and drinking water
• Fatigue and general weakness
• Dizziness and a feeling of being light-headed
• Difficulty sleeping

These symptoms usually resolve within a period between 24 and 48 hours. Descending can help you feel better more quickly. Be sure to stay hydrated and avoid alcohol and sedatives. Once the symptoms have passed, you can resume your ascent.

Emergency situations requiring immediate descent

There are two life-threatening emergency situations in which you need to descend immediately:

Number 1: you develop fluid on the lungs. This is known as HAPE (High Altitude Pulmonary Oedema). Most notably, it causes extreme shortness of breath, making you take much longer to recover from exertion. Be mindful of the following symptoms:

• Shortness of breath
• Difficulty taking a breath
• A noisy, rattling sound while breathing
• Extreme fatigue
• A persistent cough
• Blue or grey lips and fingernails
• A tendency to collapse
• Drowsiness
• Confusion

Number 2: you develop fluid in the brain. This condition is known as HACE (High Altitude Cerebral Oedema) and causes cognitive impairment: an inability to think straight. Left untreated, it can lead to a coma or even kill you. Look out for these symptoms:

• Lethargy
• Behavioural shifts
• Loss of coordination (inability to walk in a straight line)

Both conditions can appear without warning, at any time, and in those who have previously handled higher elevations without issue. They can affect people in peak physical condition and hit visitors and indigenous people alike. Taking Acetazolamide does not fully protect you.

If you develop HACE or HAPE, you must descend immediately, even during the night, and by at least 500-1,000 metres (1,500-3,000 feet). Any delay can be fatal. These conditions can be addressed with oxygen and steroid treatments, but there are no guarantees, and descending right away is critical.

Use during pregnancy or breastfeeding

Acetazolamide has been found safe for use while breastfeeding and may be deemed viable for a pregnant woman following a consultation. Pregnant women, though, should not be climbing at altitude or doing anything physically dangerous, so be extremely cautious.

What to do if Acetazolamide is unavailable

If you have no Acetazolamide to ease your trip, focus on the following precautions:

• Stay as hydrated as you can
• Avoid alcohol
• Do not smoke
• Avoid using sleeping pills
• Consume a high calorie diet
• Rest as much as you possibly can

Acetazolamide or Diamox?

Acetazolamide used to be known as Diamox tablets. However, the brand Diamox has been discontinued. The medication has since been re-branded as generic Acetazolamide 250mg tablets, which was the same active ingredient found in Diamox. Acetazolamide belongs to a category of medicines called diuretics. A diuretic is any substance that increases the production of urine, thus promoting the excretion of water from the body. Acetazolamide is manufactured by MercuryPharma. The tablet itself is white, round and convex with “FW 147” marked on one side. The other side of the tablet is scored into quarters. Acetazolamide is a prescription-only medicine (POM).