Diamox (Acetazolamide): Uses, Side Effects, and Dosages

Diamox (acetazolamide) is a medication used most commonly to treat glaucoma, epilepsy, and idiopathic intracranial hypertension, a condition of increased pressure around your brain without a known cause. It's also used to treat edema and high-altitude sickness.

Diamox is sometimes used off-label to treat other conditions, including migraines. It's not used as often as it once was because newer drugs are now available, but Diamox can still be quite helpful in some cases. However, not everyone should take Diamox, including people with severe kidney disease.

This article explains the Diamox mechanism of action, and how and why it's used. It also discusses the side effects of acetazolamide, possible drug interactions, and when it should be avoided.

How Diamox Works

Diamox is a carbonic anhydrase inhibitor. It limits the effects of the enzyme carbonic anhydrase, which is needed to convert water and carbon dioxide into bicarbonate and hydrogen ions in your body.

By inhibiting this activity, Diamox affects your body in several ways:

• It reduces the amount of acid excreted when you urinate. This causes the kidneys to excrete more bicarbonate, sodium, potassium, and water, with the urine becoming more alkaline.
• Diamox reduces the production of aqueous humor, the clear fluid produced in the eye between the lens and the cornea. This decreases both eye pressure and the rate at which spinal fluid is produced.
• Diamox produces a metabolic acidosis by increasing the urinary excretion of bicarbonate.
• Diamox seems to inhibit neuron function in the central nervous system.

These properties account for why it's used to treat a number of health conditions.

Uses

There are few health conditions that are commonly treated with Diamox.

Glaucoma

Diamox reduces the amount of fluid produced in the anterior chamber of the eye, thereby reducing intraocular pressure, the pressure within your eye. Reducing this eye pressure is a mainstay in treating glaucoma.

While Diamox is effective in reducing intraocular pressure, it offers relatively modest benefits. Newer ways of reducing eye pressure—various eyedrops and microsurgical techniques—mean that Diamox, in most cases, is used for glaucoma only in short-term situations. They include eye pressure that follows surgery or eye trauma.

High-Altitude Sickness

High-altitude sickness happens when people experience a higher elevation than they are used to, such as atop a mountain. Symptoms can vary from the annoying headache, muscle aches, dizziness, and nausea, to the life-threatening pulmonary (lung) or brain edema.

Diamox can help to prevent high-altitude sickness. It helps to combat the oxidative stress that occurs at high elevations, improving the ability of red blood cells to carry oxygen through the body and serving as a treatment for pulmonary edema.

Edema

Diamox acts as a diuretic to treat edema that occurs with conditions such as heart failure. However, it is a weak diuretic and has generally been replaced by more powerful medications like 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 cases that don't respond to other medications.

Periodic Paralysis

Periodic paralysis is a group 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. They include a condition called Andersen-Tawil syndrome.

These episodes are associated with either high (hyperkalemic) or low (hypokalemic) 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. 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.

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, the research to support its use in treating other types of migraines is limited.

Idiopathic Intracranial Hypertension (IIH)

Idiopathic intracranial hypertension (IIH) is a condition that causes increased pressure inside the head due to the accumulation of spinal fluid. This can occur because of an increase in spinal fluid production or a decrease of its absorption.

People usually have headaches, visual loss, and papilledema (swelling of the optic nerves). IIH most frequently affects obese women of childbearing age. Diamox is commonly used to treat this condition and is believed to decrease the rate of spinal fluid production. 

Before Taking

Diamox is not prescribed very often, for two main 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 long-term use.

The only two conditions for which Diamox still may be considered a drug of first choice is in IIH and in the prevention of high-altitude sickness in people transitioning to high altitudes who are at high risk for this condition.

When Diamox is used for prevention of altitude sickness, 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 are acclimated.

Before taking Diamox for any of these indications you will need to tell your healthcare provider 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.) 

Your healthcare provider also 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), and as an extended-release capsule of 500 mg. It 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 healthcare provider 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 per kilogram (kg) per 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 one 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.

IIH: Diamox is usually started with a dose of 500 mg twice a day but can be increased to 2 to 4 grams 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, for example), people are usually advised to simply tolerate the mild side effects for the duration of therapy.

However, side effects make Diamox a difficult drug to take if long-term treatment is the goal.

Common Side Effects

The most common 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 healthcare provider right away. They may include:

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

Severe Side Effects

Serious side effects are possible with Diamox, including:

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

Call your healthcare provider right away if you experience these side effects. They require immediate medical attention.

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 called anaphylaxis, with symptoms of severe dizziness, rash, severe shortness of breath, and loss of consciousness.

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. Also, 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 healthcare provider 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:

• Acetaminophen (Tylenol)
• Albuterol
• Amantadine
• Amphetamines
• Anticonvulsants
• Aspirin
• Barbiturates
• Chlorpheniramine (common in OTC cold remedies)
• Cyclosporine
• Diuretics
• Ephedrine
• Lithium
• Metformin and other oral diabetes drugs
• Nifedipine
• Primidone
• Pseudoephedrine
• Simvastatin
• Sodium bicarbonate
• Tricyclic antidepressants

Summary

Although the availability of newer medications has meant that Diamox (acetazolamide) is not used as often as it once was, it still offers benefits in treating specific medical conditions. They include IIH and high-altitude sickness prevention.

However, it may be used to treat other conditions, such as glaucoma or migraines, in certain situations. Researchers also are continuing to explore how acetazolamide and other carbonic anhydrase inhibitors might be used to treat sleep apnea, cancer, osteoporosis, and other conditions.

Diamox may have side effects and significant drug interactions, and it should not be used by everyone. Talk to your healthcare provider about its possible benefits in your specific case.

A Word From Verywell

If your healthcare provider is talking about prescribing Diamox, be sure to ask why this drug is being recommended instead of newer alternatives. Don't hesitate to act as an advocate for your own care.