What to Know About Diamox (Acetazolamide)

A Carbonic Anhydrase Inhibitor With Diverse Uses

In This Article

Diamox (acetazolamide), a carbonic anhydrase inhibitor, is used most commonly to treat glaucomaepilepsy, edema, and high-altitude sickness. Diamox is also sometimes used off-label to treat familial periodic paralysis, normal pressure hydrocephalus, and migraines. While its usage in clinical medicine has largely been supplanted by more modern drugs, Diamox can still be quite helpful in some situations.

Carbonic anhydrase is an Important enzyme In the body that converts water and carbon dioxide to bicarbonate and hydrogen ions. By inhibiting carbonic anhydrase activity, Diamox affects human physiology in several ways:

  • Diamox reduces the amount of acid excreted by the kidneys, causing the kidneys to excrete more bicarbonate, sodium, potassium, and water, and the urine to become alkaline.
    Diamox reduces the production of aqueous humor (the clear fluid produced in the eye, between the lens and the cornea), leading to a reduction in eye pressures.
  • Diamox produces a metabolic acidosis by increasing the urinary excretion of bicarbonate.
  • Diamox seems to inhibit neuronal function in the central nervous system.

These physiological alterations produced by Diamox account for its various uses in clinical medicine.

Uses

Glaucoma: Diamox reduces the amount of fluid produced in the anterior chamber of the eye, thereby reducing intraocular pressure. Reducing this eye pressure is a mainstay in treating glaucoma. While Diamox is effective in reducing intraocular pressure, the magnitude of this reduction is relatively modest. Newer ways of reducing eye pressure—various eyedrops and microsurgical techniques—have relegated Diamox to a largely secondary role in treating glaucoma. In most cases, Diamox is used today for glaucoma only in short-term situations, to manage acute elevations in eye pressure (such as after surgery or eye trauma).

High-altitude sickness: High-altitude sickness is a symptom complex brought on when some people are exposed to a substantially higher altitude than they are used to. Symptoms can vary from the annoying (headache, muscle aches, dizziness, and nausea) to life-threatening pulmonary or brain edema. Diamox can help to prevent high-altitude sickness, likely by producing respiratory and metabolic acidosis, which improves the binding of oxygen to hemoglobin and increases the respiratory rate.

Edema: Diamox acts as a diuretic that can be used to treat edema that occurs with conditions such as heart failure. However, it is a weak diuretic, and its clinical usefulness for treating edema has been largely supplanted by more powerful diuretic agents such as Lasix (furosemide).

Epilepsy: Diamox has been used to treat childhood absence epilepsy, a condition characterized by sudden "absence attacks." Newer drugs have proven far more effective than Diamox for this condition, and Diamox is now usually reserved as a third-or-fourth-line treatment in refractory cases.

Periodic paralysis: Periodic paralysis is a family of rare, usually hereditary conditions affecting the neuromuscular system, in which episodes of severe muscle weakness are triggered by fasting, high-carb meals, or heavy exertion. These episodes are associated with either high (hyperkalemic periodic paralysis) or low (hypokalemic periodic paralysis) blood potassium levels. Diamox has been found to be helpful in preventing episodes in some people with hypokalemic periodic paralysis.

Normal pressure hydrocephalus: While Diamox has been prescribed to treat this condition, a recent review concludes that there is no solid evidence that it works for this normal pressure hydrocephalus, and surgical therapy appears to be the only effective treatment.

Migraines. Diamox has been reported to be of benefit in a few cases of familial hemiplegic migraine (a rare inherited disorder characterized by migraine attacks accompanied by weakness on one side of the body). In addition, there are anecdotal reports that Diamox may be helpful in preventing other kinds of migraine headaches, in particular, migraines related to changes in the weather, or to the menstrual cycle. However, these anecdotal reports are not supported by anything resembling clinical studies.

A single randomized clinical trial was begun to see whether Diamox could provide a general prophylactic benefit for migraine sufferers who do not have familial hemiplegic migraines. The study was stopped prematurely because too many of the enrolled patients were unable to tolerate Diamox. At the time the study was terminated, no benefit could be identified among patients randomized to receive Diamox. So, except in people with familial hemiplegic migraine, there is no solid evidence from clinical studies that Diamox is of benefit to typical migraine sufferers.

Before Taking

Diamox is not prescribed very often in modern medical practice. This is for two reasons. First, for most of the uses of this drug, much newer and much more effective alternatives exist. And second, Diamox can be difficult to tolerate for chronic usage.

If your doctor is talking about prescribing Diamox for glaucoma, edema, epilepsy, normal pressure hydrocephalus, or migraines, you need to ask why this drug is being recommended instead of the available alternatives.

The only condition for which Diamox still may be considered a drug of first choice is in the prevention of high-altitude sickness in people who are transitioning to high altitudes, and are judged to be at high risk for this condition. Even in these cases, however, the much-preferred approach is to engage in gradual ascent and prolonged acclimation to the higher altitudes, along with avoidance of alcohol and sedatives for several days before ascending. When Diamox is used for this purpose, you will need to begin taking it at least a day before ascent, and treatment will have to continue for at least 48 hours after you have reached the new elevation, or until you have acclimatized. 

Before taking Diamox for any of these indications you will need to tell your doctor if you have any allergies, particularly allergies to Diamox or other sulfonamides. (Diamox, like some antibiotics, thiazide diuretics, and some oral hypoglycemic drugs, is a sulfonamide.) 

Also, prior to taking this drug, your doctor will need to evaluate whether you are prone to breathing problems, dehydration, diabetes, or hyperthyroidism. Any of these conditions can make side effects with Diamox more likely. Side effects are also more likely to occur in the elderly, and in pregnant women, and this drug should be avoided if possible in women who are breast feeding.

Dosage

Diamox is provided as a tablet of 125 and 250 milligrams (mg), as an extended-release capsule (500 mg), and can also be given intravenously.

Note that all the dosages listed below are according to the drug manufacturer or published studies. If you are taking Diamox, be sure to check your prescription and talk to your doctor to make sure you are taking the right dose for you.

Glaucoma: For open-angle glaucoma, the usual dose is 250 mg tablets up to four times a day, or 500 mg extended release capsule twice per day. In the management of acute close-angle glaucoma Diamox is sometimes given intravenously to rapidly reduce eye pressure while awaiting surgery, typically at a dose of 500 mg.

Edema. When used as a diuretic, Diamox is typically given in tablet form, 250-375 mg once daily.

Epilepsy. In treating childhood absence epilepsy, Diamox is usually given as 4 to 16 mg/kg/day in up to four divided doses, but the dosage can go as high as 30 mg/kg/day if necessary to control symptoms.

High-altitude sickness. To prevent high altitude sickness, Diamox should be started on the day before ascent at a dose of 125 mg twice per day, and continued while staying at the higher elevation for an additional two to three days. In situations where rapid ascent is required, 1000 mg per day can be used.

Periodic paralysis. Diamox is usually given as 250 mg tablets, from once to three times daily.

Normal pressure hydrocephalus. When used for this condition, Diamox is typically given as 125 mg tablets, from one to three times a day.

Migraines. When used to treat familial hemiplegic migraines, Diamox is usually prescribed as 250 mg tablets, twice per day.

How to Take and Store

Diamox tablets and capsules are taken by mouth, and can be taken with or without food. The capsules should be swallowed whole, and should not be broken apart or chewed. Because Diamox can cause dehydration, people taking this medicine should be sure to drink plenty of fluid.

Diamox should be stored at room temperature, between 68 to 77 degrees Fahrenheit.

Side Effects

Unpleasant side effects with Diamox are frequent. Since the most common usages of this drug are temporary (the short-term treatment of glaucoma or edema, and prophylactic treatment for high-altitude sickness), people are usually advised to simply tolerate the mild side effects for the duration of therapy. However, side effects have made Diamox a difficult drug to take if long-term treatment is desired.

Common

The most common milder side effects with Diamox include:

  • Lightheadedness and dizziness
  • Increased urination
  • Dry mouth
  • Blurred vision
  • Loss of appetite
  • Nausea
  • Headache
  • Tiredness
  • Blurred vision
  • Increased blood sugar
  • Increased sensitivity to the sun

In addition, many people report an annoying change in their taste sensation. This seems to be especially the case with regard to carbonated beverages; Diamox can make these beverages quite unpleasant to the taste.

Some side effects are more difficult to tolerate. If these more troublesome side effects occur, you should report them to your doctor right away. They may include:

  • Ringing in the ears
  • Hearing loss
  • Increased body hair
  • Persistent nausea and vomiting
  • Severe abdominal pain

Severe

Serious side effects are also possible with Diamox that require immediate medical attention, including:

  • Easy bleeding or bruising
  • Infections
  • Mood changes or difficulty concentrating
  • Palpitations or rapid heart beat
  • Severe muscle cramping
  • Jaundice

Allergic reactions to Diamox are relatively uncommon, but they do occur. Symptoms may be relatively mild (rash, itching, mouth blisters), or may be a life-threatening emergency (anaphylaxis, including severe dizziness, rash, severe shortness of breath, and loss of consciousness).

Any sign of an allergic reaction to any drug should be reported right away to your doctor, and if signs suggesting anaphylaxis occur, 911 should be called immediately.

Warnings and Interactions

Sometimes Diamox may cause impaired mental alertness or physical incoordination, so caution should be taken if driving or operating machinery. 

People with diabetes may see a change in blood glucose control with Diamox, which may cause blood glucose levels to become either lower or higher.

Diamox may worsen chronic liver disease.

People with severe chronic lung disease may experience more breathing difficulty while taking Diamox.

Diamox can make sunburn more likely. People should avoid prolonged exposure to sunlight while on Diamox, especially if they get sunburned easily.

Many drug interactions have been reported with Diamox, so it is important that your doctor know all the medicines and supplements you may be taking, whether from prescriptions or over the counter. Some of the notable drugs that can negatively interact with Diamox include:

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  1. Vass C, Hirn C, Sycha T, Findl O, BauerP, Schmetterer L. Medical interventions for primary open angle glaucoma and ocular hypertension. Cochrane Database Syst Rev 2007;:CD003167. DOI:10.1002/14651858.CD003167.pub3

  2. Grissom CK, Roach RC, Sarnquist FH, Hackett PH. Acetazolamide in the treatment of acute mountain sickness: clinical efficacy and effect on gas exchange. Ann Intern Med 1992; 116:461. DOI:10.7326/0003-4819-116-6-461

  3. Fontaine B. Periodic paralysis. Adv Genet 2008; 63:3. DOI:10.1016/S0065-2660(08)01001-8

  4. Williams MA, Malm J. Diagnosis and treatment of idiopathic normal pressure hydrocephalus. Continuum. 2016 Apr;22(2 Dementia):579-599. doi:10.1212/CON.0000000000000305

  5. Battistini S, Stenirri S, Piatti M, et al. A new CACNA1A gene mutation in acetazolamide-responsive familial hemiplegic migraine and ataxia. Neurology 1999; 53:38. DOI:10.1212/wnl.53.1.38

  6. Vahedi K, Taupin P, Djomby R, et al. Efficacy and tolerability of acetazolamide in migraine prophylaxis: a randomized placebo-controlled trial. J Neurol. 2002 Feb;249(2):206-11.