Acetazolamide

What is acetazolamide?

Acetazolamide is a diuretic and carbonic anhydrase inhibitor which is used to treat several conditions, including glaucoma, congestive heart failure, and altitude sickness.

It acts on the kidneys to remove bicarbonate from the body via urine, reducing alkalinity, and preventing the symptoms of altitude sickness.

How does acetazolamide work?

Acetazolamide works to prevent and reduce the symptoms of altitude sickness, such as shortness of breath, nausea, dizziness, tiredness, and headaches.

Acetazolamide works to remove bicarbonate from the body and alkalises the urine. As a result, your blood becomes more acidic, causing your body to maintain and even increase its oxygen intake. That’s because carbon dioxide concentration reflects acidity, so by removing bicarbonate, the body reacts to what it believes is excess carbon dioxide.

By compensating for this, acetazolamide causes faster and deeper breathing, increasing the amount of oxygen in the blood and helping your body to acclimatise to higher altitude levels.

How effective is acetazolamide?

Research shows that acetazolamide is effective at preventing altitude sickness if taken two days before arriving in an area at high altitude.

A systematic review including 22 trials, found that acetazolamide at 125, 250, and 375 mg was associated with a significant reduction in acute mountain sickness compared to placebo. The study also found that 125 mg was the lowest effective dose for preventing altitude sickness.

Acetazolamide dosage

If acetazolamide is prescribed to prevent altitude sickness, perhaps because you have experienced it before or must ascend quickly, the usual dose is 125 mg of acetazolamide twice daily. You should start treatment one to two days before you ascend and continue taking acetazolamide for 48 hours or until you have reached the peak of your trip.

What happens if I take too much acetazolamide?

If you take more acetazolamide than you have been prescribed, you should contact a doctor straight away or go to the nearest emergency department for help.

What if I miss an acetazolamide dose?

If you forget to take an acetazolamide dose, you should take it as soon as you remember. If this is within 2 hours of your next dose, skip the missed dose completely, and continue taking the rest of the tablets as prescribed. You must not take a double dose to compensate for a missed dose.

How to take acetazolamide

You should take acetazolamide exactly as you have been told to by a clinician. Check with a doctor, nurse or one of our clinicians if you are unsure how to take it.

When taking acetazolamide tablets, you should:

• Swallow them whole with a glass of water
• Take them just before or just after a meal
• Avoid chewing or crushing the tablets

Acetazolamide side effects

Like any medication, it can cause side effects, although not everyone experiences them. Some common side effects of acetazolamide include:

• Frequent urination
• Tingling or numbness in hands or feet (paresthesia)
• Loss of appetite
• Taste alterations
• Nausea or vomiting
• Diarrhea
• Dizziness
• Drowsiness
• Headache
• Confusion or changes in mental status

Acetazolamide warnings and contraindications

Acetazolamide may not be suitable for everyone, you should not take it if you:

• Are allergic to any of the ingredients listed in acetazolamide sulphonamides or sulphonamide derivatives
• Have liver problems
• Have you ever had kidney problems
• Have a type of glaucoma called chronic non-congestive angle closure glaucoma
• Know if your adrenal glands do not function properly or have Addison’s disease
• Have low blood sodium or potassium or high blood levels of chlorine

You should also let our clinicians know if you experience or have experienced any of the following before taking acetazolamide:

• Kidney problems, such as kidney stones
• Lung problems, like chronic bronchitis or emphysema
• Are over 65 years old
• Thoughts of harming or killing yourself

Acetazolamide and drug interactions

You should tell our clinicians straight away if you are taking or have taken any of the following medications:

• Heart medicines like cardiac glycosides
• Blood pressure-lowering medicines
• Blood thinners like warfarin or aspirin
• Blood sugar-lowering medicines such as metformin or gliclazide
• Epilepsy medicines such as phenytoin, primidone, carbamazepine or topiramate
• Drugs that interfere with folic acid such as trimethoprim, pyrimethamine, or methotrexate
• Steroids
• Other carbonic anhydrase inhibitors
• Amphetamines, quinidine, methenamine or lithium
• Sodium bicarbonate therapy
• Ciclosporin

Can I take acetazolamide if I am pregnant or breastfeeding?

You should not take acetazolamide if you are pregnant, trying to get pregnant or think you might be pregnant.

You may be able to take acetazolamide tablets while breastfeeding but you should follow the advice of your clinician.

Can I buy acetazolamide online?

You can buy acetazolamide online from Prescription Doctor using our online consultation service. Our team recommends obtaining your supply of acetazolamide well in advance of your trip to make sure you can begin your treatment on time.

To buy acetazolamide for altitude sickness, you will need to:

• Complete our online medical questionnaire
• One of our clinicians will review your responses
• If approved, your medicine will be sent out to you in discreet packaging (if it is approved before 3 pm, it will be dispatched for next-day delivery)
• If our clinician doesn’t feel acetazolamide is appropriate, you will receive a full refund as part of the Prescription Doctor money-back guarantee.

FAQs

What is altitude sickness?

Altitude sickness occurs when your body has difficulty adjusting to lower oxygen availability at high altitudes. It causes symptoms such as headaches, feeling or being sick, tiredness, dizziness, trouble sleeping, and a loss of appetite.

How can I prevent altitude sickness?

There are some things you can do to prevent altitude sickness from occurring, like:

• Climb to a high altitude slowly over a few days to help your body acclimatise to low oxygen levels
• Spend a few days at an altitude below 2500 metres
• Incorporate rest days
• Drink plenty of water to stay hydrated throughout your trip

Are there alternatives to acetazolamide available?

Acetazolamide is a generic medicine, branded versions are available, such as Eytazox, but it still contains the active ingredient, acetazolamide.