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|Type of medicine||Carbonic anhydrase inhibitor|
|Works by||Counteracts respiratory alkalosis|
|Effective within||2 hours|
|Pack size||28 Tablets|
|Common side effects||Dizziness, Lightheadedness, Increased Urine Production, Blurred Vision, Dry Mouth, Drowsiness, Loss of Appetite, Stomach Upset, Headache and Tiredness|
|Manufacturer||AAH Pharmaceuticals, Advanz Pharma, Alliance Healthcare, Crescent Pharma, DE Pharmaceuticals, DAWA, Genesis Pharmaceuticals, Medihealth, Phoenix Healthcare Distribution, Sigma Pharmaceuticals|
|Use with alcohol||No known effect|
Acetazolamide (Diamox) Information
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).
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
worksto 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
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:
- 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).
Acetazolamide (Diamox) dosage
Your required dose of Acetazolamide will depend on the severity of your symptoms and you should read the leaflet that is supplied for more detailed information. You or a member of your group will need to decide on the most appropriate treatment. If you have a doctor or other healthcare professional on your trip, you should seek their advice.
Here are some general guidelines:
- Take a trial dose of half a tablet 3-4 days before travel to check for possible adverse reactions.
- Taking to prevent mountain sickness or to help to acclimatise the dose is 125mg (half a tablet) twice daily until you have been at the highest altitude for 2-3 days.
- To treat mild early acute mountain sickness (headache, fatigue, lightheadedness, difficulty sleeping), take one 250mg tablet of Acetazolamide 250mg twice daily until symptoms resolve. You can then resume climbing.
- To prepare for rapid ascent without proper acclimatisation, take one 250mg tablet of Acetazolamide twice daily, beginning the day before ascent or as soon as possible after beginning, and keep taking the tablets for a few days after reaching final altitude.
- To treat disturbed breathing patterns, take half of one 250mg tablet of Acetazolamide twice daily until reaching an altitude comfortable for sleeping.
Remember: even if you take Acetazolamide, it is still important to properly acclimatise. You should never ascend further until your symptoms have completely gone and you are properly acclimatized to your current altitude. Do not use Acetazolamide to push through the symptoms of altitude sickness and continue to climb, this is extremely dangerous and can be fatal.
Each tablet contains the active ingredient acetazolamide 250mg.
It also contains:
- Lactose monohydrate
- Corn starch
- Sodium starch glycolate type A potato
- Magnesium stearate
Acetazolamide (Diamox) side effects
The following side effects can occur when taking Acetazolamide:
- Increased urine production
- Blurred vision
- Dry mouth
- Loss of appetite
- Stomach upset
- Headache and tiredness
You’re most likely to develop side effects while your body is getting used to the medicine.
Tell your doctor immediately if any of these very unlikely but serious side effects occur:
- Increased body hair
- Hearing loss
- Ringing in the ears
- Unusual tiredness
- Persistent nausea/vomiting
- Severe stomach/abdominal pain
Seek immediate medical attention if any of these unlikely but very serious side effects occur:
- Easy bleeding/bruising
- Fast/irregular heartbeat
- Signs of infection (e.g., fever, persistent sore throat)
- Mental/mood changes (e.g. confusion, difficulty concentrating)
- Severe muscle cramps/pain
- Tingling of the hands/feet
- Blood in the urine
- Dark urine
- Painful urination
- Yellowing of the eyes/skin
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include:
- Blisters/sores in the mouth
- Itching/swelling (especially of the face/tongue/throat)
- Severe dizziness
- Trouble breathing
If you experience any adverse effects from taking Acetazolamide, inform your trip doctor immediately. In a medical emergency, contact emergency services or go straight to a hospital or medical centre.
Acetazolamide (Diamox) warnings
Acetazolamide is not suitable for use if you:
- Are allergic or sensitive to or have had a bad reaction to sulphonamides in the past
- Have adrenal gland problems
- Have chronic obstructive pulmonary disease
- Have closed-angle glaucoma
- Have had kidney stones
- Have kidney or liver problems
Acetazolamide 250mg Tablets reviews
Acetazolamide 250mg Tablets FAQs
Acetazolamide is a prescription medicine known as a diuretic, which means it increases the production of urine, thus promoting the excretion of water from the body. Through inhibiting an enzyme in the body called ‘carbonic anhydrase’, it slows down certain chemical reactions in the body, changing the acidity of the blood. The net result of this is an improvement in breathing and a reduction in fluid around the brain and in the lungs. It is very important to drink a lot of fluid whilst taking Acetazolamide; at least two to three litres of water per day.
Taking Acetazolamide for initial symptoms should not be viewed as a green light to keep climbing. Ascent should cease until the symptoms have completely resolved, which in most cases will be within 48 hours. Acetazolamide will not protect you against your symptoms worsening if you continue to ascend; plenty of climbers who have done this have gone on to develop either HAPE or HACE.
Acetazolamide will help reduce the risk of altitude sickness on rapid ascents, but it is not a substitute for following proper protocols and correct precautions. Rapid ascents carry serious risks and Acetazolamide does not remove them. In fact, it can make climbers feel safe enough to push through their illness, leading to much more severe conditions. When altitude sickness strikes, it may be sudden, severe and possibly fatal.
Treat altitude with respect and do not imagine that you can simply battle through because you are strong and fit. People who climb and hike in high places have a reputation for pushing themselves. When it comes to altitude, preparation, planning ahead, taking one’s time and listening to one’s own body are the key to safety.
Acetazolamide does not mask serious underlying symptoms; the medication treats the cause not the symptoms. Acetazolamide accelerates acclimatisation. As acclimatisation occurs, the symptoms will resolve. Acetazolamide does not mask anything; if you are still unwell then your symptoms will persist despite the medication.
If you feel better when you are taking Acetazolamide, it is because your underlying condition has improved. If you stop taking Acetazolamide, your acclimatisation will slow down to its natural rate, enabling you to gauge how well your recovery is progressing.
Even in its mildest form, altitude sickness can have a very negative impact on what should otherwise be an enjoyable experience. In severe cases, it can put your health at serious risk, sometimes even requiring hospitalisation. Acetazolamide tablets can help to prevent issues caused by altitude sickness or mountain sickness, provided they are used in conjunction with appropriate precautionary measures such as acclimatisation.
Acetazolamide is classed as a ‘sulphonamide derivative’ so if you are sensitive tosulphonamides, you should not take this medication. There are other conditions and some prescription drugs which are not compatible with Acetazolamide, so be sure to consult a doctor and understand the warnings before taking it.
Yes you can drink alcohol whilst taking Acetazolamide tablets but it is not advisable if you are experiencing the symptoms of altitude sickness. Alcohol can make the symptoms of altitude sickness worse.
Yes you can drive and take Acetazolamide tablets, however if you notice any adverse reactions or side effects, you cease taking the medication and discuss the symptoms with your doctor.
Acetazolamide is a prescription-only drug, so you cannot buy it over the counter before going on holiday. You must allow enough time to make an appointment with your GP ahead of time, or use our online service which can issue you with a doctor-verified prescription based on your responses to our health questionnaire.
Acetazolamide tablets come in a handy 250mg size making them very easy to store and take whilst on the move. It is recommended that you store the tablets in a safe and secure environment at a temperature below thirty degrees centigrade, preferably at room temperature. Always keep Diamox tablets out of the reach of children.
Acetazolamide used to be sold as Diamox, but the Diamox brand was discontinued. Since acetazolamide was the active ingredient in Diamox tablets, it was rebranded as Acetazolamide.
Acetazolamide is manufactured by Mercury Pharmaceuticals Ltd., Capital House, 85 King William Street, London EC4N 7BL, UK.