Acetazolamide is a type of diuretic (water pill) known as a carbonic anhydrase inhibitor. It is used for treating certain types of seizures and glaucoma, and limiting the build-up of body fluids caused by congestive heart failure. It is also commonly used to manage altitude sickness by decreasing symptoms such as headaches, tiredness, nausea, dizziness and shortness of breath, which occur upon ascension to high altitudes - usually above 3,000 metres.
Acetazolamide is not an immediate cure for altitude sickness - it speeds up the process of acclimatization and reduces symptoms. It causes the kidneys to excrete bicarbonate, causing the blood to become more acidic. This rise in blood-acidity tricks the body into thinking it has an excess of CO2, which is seeks to excrete through deeper and more regular breathing. In doing so, the body increases the amount of oxygen in the blood, which helps reduce the symptoms of altitude sickness.
Acetazolamide can help you adjust to high altitudes and prevent the symptoms of altitude sickness, and is taken by those who are planning a walk or climb to high altitudes. This medication should be started 1-2 days before you begin to ascend to high altitudes, and normal precautions should be followed. Acetazolamide can be used to reduce the symptoms of altitude sickness, but will not completely cure them. If you are already taking acetazolamide and begin to experience altitude sickness, it is important that you stop your ascent or descend by at least 500m.
For treatment of altitude sickness, Acetazolamide is usually taken in a preventative capacity. It should be taken between 24 and 48 hours before you begin your ascent to altitudes of 3,00m and above in order to allow the body to register the treatment and adjust accordingly. You should continue to take acetazolamide as you ascend, and for 24 hours after remaining at a constant altitude.
The true efficiency of Acetazolamide in treating the symptoms of altitude sickness after they occur is unknown. The treatment can take up to 48 hours to take effect, by which time your body may well have adjusted on its own.
Acetazolamide was originally licensed for use in the treatment of glaucoma and epilepsy. However, it has also been found to be an effective method to prevent altitude sickness. The original license has not been extended to cover altitude sickness, but this does not mean that it is unsafe or ineffective. It is an expensive process to get a license extended, so manufacturers often avoid doing this. Doctors are able to prescribe medications off-label when there is evidence to suggest that it is the most appropriate treatment available. The NHS has produced a useful document on this subject which you can access here for more information.
When travelling to altitudes above 3,000 metres, the best way to acclimate yourself and avoid altitude sickness is to make your ascent slowly. It usually takes the body a few days to get used to a change in altitude, so you should take 2-3 days to rest and adapt before ascending further than 3,000m. The following precautions should be taken as you ascent further:
Symptoms of altitude sickness can includes headaches, nausea and vomiting, dizziness, tiredness, loss of appetite and shortness of breath. These symptoms commonly worsen at during nighttime. If you think you have symptoms of altitude sickness, the following advice may help:
The active ingredient is acetazolamide. Each tablet contains a 250mg dose of acetazolamide.
The inactive ingredients in acetazolamide 250mg tablets are dicalcium phosphate, corn starch, magnesium stearate, sodium starch glycolate and povidone.
Please Note: Inactive ingredients may vary between different brands of generic medication.
Acetazolamide for altitude sickness should not be crushed or chewed. Tablets are designed to work over an extended period of time and should be swallowed whole with a drink of water.
Most importantly, take Acetazolamide as instructed by your doctor and according to the packet information. Long-acting tablets (250 mg) should be taken twice daily, beginning at least 24 hours before ascending to high altitudes (3,000m and above). These tablets are designed for extended release, so it is essential that you do not chew or crush them, but swallow them whole with a drink of water.
Once tablet contains 250 mg of acetazolamide. For rapid ascension to high altitude, take one tablet twice daily, beginning 1 or 2 days before you begin your ascent. If taking this medication in relieve symptoms of altitude sickness, take half a tablet twice daily.
Some people may experience mild side effects when taking Acetazolamide, including:
Less common side effects include:
Like all medicine, Acetazolamide can cause serious allergic reactions, although this is very rare. You should contact a doctor immediately if you experience any sudden wheezing, difficulty breathing, swelling of the eyelids, face or lips, rash or itching.
In extremely rare cases, Acetazolamide can affect blood cells, increasing your chance of catching infections and affecting your blood’s ability to clot properly. Contact your doctor immediately if you have a sore throat or fever, or notice bruises or tiny red spots on your skin whilst taking this medication. If your muscles feel weak, or you are having fits, seek urgent medical attention.
Acetazolamide can also very rarely affect the liver and kidneys. You should contact a doctor if you experience pain in your lower back, pain or difficulty passing urine, inability to pass urine, blood in your urine, pale stools, or yellowing of your skin or the whites of your eyes.
You should not take Acetazolamide tablets if:
You should let your doctor know if you are taking other medications or plan to take other medications whilst taking Acetazolamide. The effects of the following medications in particular may be altered by taking Acetazolamide:
Alcohol should be avoided when taking Acetazolamide as the combination increases the risk of experiencing drowsiness. If taking Acetazolamide for altitude sickness, alcohol should be avoided at all costs, as the dehydrating effect of alcohol can make the symptoms of altitude sickness worse.
Diamox is a brand name for acetazolamide, which is the generic name for the drug. As of April 2015 it is not longer possible to buy Diamox in the UK. The treatment is now sold simply as ‘acetazolamide’, and contains the same dosage and ingredients.
There are measures for managing altitude sickness which should be followed regardless of whether you have chosen to take Acetazolamide. Acetazolamide is designed to reduce the severity of your symptoms rather than prevent or cure them altogether. Taking the following precautions can be equally as effective in preventing altitude sickness:
If you begin to experience symptoms of altitude sickness, see the following measures:
Acetazolamide cannot be bought over the counter, but must be prescribed by a travel doctor, GP or online pharmacy. Although it is not currently licensed in the UK as a treatment for altitude sickness, it can be legally prescribed for this purpose.
There is some evidence to suggest that Acetazolamide can help lower blood pressure. Through encouraging the body to increase its oxygen intake, Acetazolamide helps reduce the rise in blood pressure associated with an increase in altitude in particular.
Ménière’s disease is characterised by vertigo, a ringing sound in the inner ear, a feeling of pressure deep inside the ear and a sudden loss of hearing. While the exact cause of Ménière’s disease is unknown, it’s associated with an increase in pressure inside the inner ear.
The most common treatments recommended by GPs are Prochlorperazine, which helps relieve severe nausea and vomiting, and antihistamines, which help relieve mild nausea, vomiting and vertigo. However, diuretics such as Acetazolamide are used by some to treat Ménière’s disease, relieving the inner ear fluid build-up and reducing vertigo and hearing loss.
Those who suffer from migraines triggered by travelling to high altitudes may find that taking acetazolamide 2-3 days before their trip prevents migraines from occurring. However, there is little evidence to suggest that taking acetazolamide is beneficial to those who suffer from migraines that are unrelated to altitude.
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