Diamox (acetazolamide)

Diamox (acetazolamide)

Diamox (Acetazolamide) contains the active ingredient acetazolamide and is used to remove excess fluid from the body. It is also used to treat the symptoms of altitude sickness and some forms of epilepsy. More information

A doctor will review your order and write you a prescription, if appropriate. This prescription is then forwarded to a pharmacy. The pharmacy will have your medicine delivered to you within one to three working days. Read more about this process here.

Instruction costs (includes consult & service fee)
Service – Instruction costs (includes consult & service fee)
Patient Leaflet(s)

Diamox (Acetazolamide) is used to reduce and prevent the symptoms of altitude sickness, treat glaucoma (a vision problem), treat oedema (fluid build-up) and for some types of epilepsy. It is a diuretic (water tablet) that aids the removal of excess water from the body, which can occur in a variety of medical conditions.

What is Diamox (Acetazolamide)? 

Diamox (Acetazolamide) contains the active ingredient acetazolamide and is used to remove excess fluid from the body. It is also used to treat the symptoms of altitude sickness and some forms of epilepsy.  It works by blocking carbonic anhydrase, a protein which contributes to fluid retention. This medicine is a diuretic which helps the kidneys remove excess fluid from the body. When you take Diamox (Acetazolamide) the amount of salt (bicarbonate) in the kidneys increases. This helps to rid the body of excess fluid through urinating more than usual as salt attracts water. 

When is Diamox (Acetazolamide) used? 

Diamox (Acetazolamide) is used to treat various conditions including altitude sickness, glaucoma fluid retention (oedema), and epilepsy.

Altitude sickness can take place when a person ascends to a height of more than 2,500 metres (8,000 feet) above sea level very quickly. It is common in climbers and skiers who climb high mountains and hills. It can also appear in people who fly to high altitude directly and rapidly.  Diamox (Acetazolamide) can be taken before an ascent to above 2,500 metres to prevent these symptoms occurring. It can also be taken if the symptoms appear after climbing and a rapid descent is not possible. This is because a slow descent can assist the symptoms of altitude sickness, but may not always be feasible due to the weather or dangerous conditions. It is advisable not just to rely on medication if you are going to travel to altitude, but to also acclimatise your body to the change. 

Altitude sickness is also known as acute mountain sickness (ACM). The symptoms include: 

  • Feeling sick 
  • Feeling faint and/or dizzy 
  • General body weakness  
  • Breathing difficulties,  
  • Headaches 
  • Vision problems 
  • Fatigue 
  • Loss of appetite 
  • Inability to sleep 
  • Poor judgement 

Altitude sickness occurs because the air pressure decreases the higher a person ascends, meaning there is less oxygen to breathe. It is a mild condition but if not treated can rapidly lead to a medical emergency such as high altitude cerebral oedema (HACE) which is the swelling of the brain due to a lack of oxygen. 

Glaucoma is an eye condition that occurs when the optic nerve (the nerve that connects the eye to the brain) is damaged. It can lead to a permanent loss of vision if left untreated. Glaucoma is caused by a build-up of fluid in the eye which increases pressure and damages the optic nerve. It usually develops slowly over several years. 

It tends to mostly occur in older adults but it is also possible to suffer from glaucoma if you are young. Other high-risk groups are people of African, Asian or Caribbean origin, those with a family history of glaucoma, people with other eye conditions such as long or short-sightedness and diabetics.Diamox (Acetazolamide) is used to treat glaucoma as it can reduce the build-up of fluid. 

Diamox (Acetazolamide) is also used to treat fluid retention in the body, which is known as oedema, in combination with other medication. This is when part of the body swells due to injury or infection. The small blood vessels leak fluid into body tissue which makes it swell. This can occur in any part of the body.  

Epilepsy causes seizures (fits) and is a condition that affects the brain. A seizure temporarily affects how the brain functions.  The nerve cells in the brain link to each other through electrical activity. If there is a sudden burst of activity this alters the balance of the brain and over-stimulates it. When this happens an epileptic person may experience a seizure.  Diamox (Acetazolamide) can be used to stabilise this electrical brain activity by altering the balance of chemicals in the blood. This can change the rhythm of the electrical activity and stabilise the brain’s nerve activity. 

How do you use Diamox (Acetazolamide)? 

You should take Diamox (Acetazolamide) with water and swallow the tablet whole. Do not chew it or the effect will be reduced and the side effects could increase. Try and take Diamox (Acetazolamide) with food if it makes you feel nauseous or gives you diarrhoea. 

The dosage required depends on the reason for taking this medicine and a doctor’s instructions should be followed. If you are taking Diamox (Acetazolamide) to prevent altitude sickness you should begin to take the tablets 1 or 2 days before you ascend your destination. You should continue to take this medicine after you reach a high altitude for a minimum of 48 hours in order to control the possible symptoms. Note that if your symptoms become severe you should consider descending and seek medical advice. This medication will not protect you from severe altitude sickness. 

Always take Diamox (Acetazolamide) at the same time every day, whatever reason you are taking it. This will help you remember to take it and ensure the medicine works on your body in a balanced way. As Diamox (Acetazolamide) is likely to cause you to urinate more often it is advisable to take your last dose early in the evening to prevent you having to get up in the night once or more.  

What dosages are there? 

Diamox (Acetazolamide) comes in the form of a 250mg tablet. There are different dosages depending on the condition you are taking it for. Always follow the advice of your doctor when taking this medicine and never take more than the prescribed dose. 

Below are the usual dosages: 

  • Altitude sickness: one 250mg tablet every day prior to and during a climb 
  • Glaucoma: adults 250mg-1g in divided doses. 
  • Fluid retention: adults 250-375 mg tablets daily in the morning 
  • Epilepsy: adults 250mg-1g in divided doses 

This medication may be prescribed to children and the dosage will depend on their body weight. It is also important not to suddenly stop this medicine as your condition could get worse. When and if it is the right time to stop taking Diamox (Acetazolamide) your doctor will advise you on how to do this. It is also important to note that this medicine can change its effectiveness when used for long periods. Therefore you should visit your doctor regularly to monitor your condition and check if your dose needs to be changed. 

What are the side effects of Diamox (Acetazolamide)? 

As with all medicines, Diamox (Acetazolamide) may cause side effects. These will vary as everyone reacts differently to medication. The most common side effects to be aware of are: 

  • Needing to urinate more often 
  • Feeling thirsty 
  • Feeling sick 
  • Sickness and/or diarrhea 
  • Headaches 
  • Dizziness 
  • Feeling tired or irritable 
  • Feeling over-excited 
  • Loss of appetite 

You are more likely to experience side effects in the first few days of taking Diamox (Acetazolamide) as your body adjusts to it. You may notice that the side effects soon disappear. If you are concerned about side effects when taking Diamox (Acetazolamide) you should speak to your doctor.  

When shouldn’t you use Diamox (Acetazolamide)? 

Before taking Diamox (Acetazolamide) you should inform your doctor if you are taking any other medication or are allergic to any of the ingredients in this medication (refer to the package leaflet).  

You should not use Diamox (Acetazolamide) if you suffer from any of the following: 

  • Underactive adrenal glands 
  • Kidney disease 
  • Liver disease 
  • High levels of potassium or sodium in your blood 
  • High levels of chloride in your blood 
  • Chronic non-congestive angle-closure glaucoma 

You should not take Diamox (Acetazolamide) if you are pregnant or are planning to become pregnant. You may take it when breastfeeding on the advice of a doctor.  Care should be taken when driving or operating machinery after taking Diamox (Acetazolamide) as it can make you feel drowsy and cause dizziness.  It is advisable not to drink alcohol or to reduce your alcohol consumption when taking Diamox (Acetazolamide) as it can make the side effects stronger. 

Does Diamox (Acetazolamide) interact with other medication? 

Diamox (Acetazolamide) can interact with other medicines so it is essential you inform your doctor if you are taking any other medication. This includes herbal medicines and medicines you may be taking that do not have a prescription. 

Diamox (Acetazolamide) can change the effects of some medicines and in particular, you should take care when taking the following: 

  • Heart medication 
  • Blood pressure medication 
  • Blood-thinning medication 
  • Aspirin 
  • Medication to lower blood sugar levels 
  • Epilepsy medication 
  • Steroids 
  • Medication containing folic acid 
  • Amphetamines 
  • Carbonic anhydrase inhibitors 
  • Medication to suppress the immune system 
  • Medication to treat high acid levels in the body 

Where can you buy Diamox (Acetazolamide)? 

You can get Diamox (Acetazolamide) at a pharmacy with a prescription. 

Can I get Diamox (Acetazolamide) without a prescription? 

No, Diamox (Acetazolamide) is a prescription-only medicine.  



Acetazolamide. September 15, 2017. Retrieved 24 August, 2019 from https://medlineplus.gov/druginfo/meds/a682756.html 

Diamox (Acetazolamide) tablet. Retrieved 24 August, 2019 from https://www.webmd.com/drugs/2/drug-6753-104/Diamox (Acetazolamide)-tablet/details 

Facts about Glaucoma. Retrieved 24 August, 2019 from https://nei.nih.gov/health/glaucoma/glaucoma_facts 

Nordqvist, C. (2018, January 30).  What's to know about altitude sickness? Retrieved 24 August, 2019 from https://www.medicalnewstoday.com/articles/179819.php

Assessed by:

Dr Imran Malik, General practitioner
Registration number: GMC: 4741365

Dr Imran Malik studied undergraduate medicine at King's College University in Central London and clinical studies at the prestigious King's College Hospital. He graduated with a MBBS degree in 2000 and went on to gain postgraduate memberships with the Royal Society of Medicine and also General Practice in 2006.