What are the uses of acetazolamide?

October 8, 2025 •

4 min read

In 2022, an estimated 4.2 million Americans were living with glaucoma, a condition acetazolamide is often used to treat by lowering eye pressure. So, what are the uses of acetazolamide beyond this common application? This medication serves a variety of therapeutic purposes.

Quick Summary

Acetazolamide is a versatile medication primarily used to treat glaucoma, prevent and lessen symptoms of altitude sickness, reduce fluid retention (edema), and manage certain seizures.

Key Points

Primary Uses: Acetazolamide is FDA-approved to treat glaucoma, altitude sickness, edema from congestive heart failure, and certain types of epilepsy.
Mechanism: It is a carbonic anhydrase inhibitor that works by reducing fluid production in the eyes and brain, and promoting the excretion of water and electrolytes by the kidneys.
Glaucoma Treatment: It lowers high intraocular pressure by decreasing the production of aqueous humor fluid inside the eye.
Altitude Sickness Prevention: It speeds up acclimatization by inducing metabolic acidosis, which stimulates breathing and increases oxygenation at high altitudes.
Diuretic Effect: For edema, it acts as a diuretic to help remove excess fluid and salt from the body.
Epilepsy Control: It is used as an add-on therapy to help manage seizures, likely by causing acidosis in the central nervous system.
Side Effects: Common side effects include tingling in the hands and feet, fatigue, and increased urination. Serious side effects can include electrolyte imbalances and kidney stones.

Understanding Acetazolamide: Mechanism of Action

Acetazolamide is a medication belonging to a class of drugs known as carbonic anhydrase inhibitors. The enzyme carbonic anhydrase is found throughout the body, including in red blood cells and the kidneys, and it plays a key role in managing the body's acid-base balance. By inhibiting this enzyme, acetazolamide causes an accumulation of carbonic acid, which leads to several physiological effects.

Its primary actions include:

Decreasing Fluid Production: In the eyes, it reduces the secretion of aqueous humor, which in turn lowers intraocular pressure (IOP). Similarly, it can decrease the production of cerebrospinal fluid (CSF), which helps lower intracranial pressure.
Promoting Diuresis: In the kidneys, it blocks the reabsorption of bicarbonate, sodium, and water, leading to increased urination (diuresis). This helps to remove excess fluid from the body.
Inducing Metabolic Acidosis: By increasing the excretion of bicarbonate, the blood becomes more acidic. This change can act as a respiratory stimulant, which is the key mechanism for treating altitude sickness.

FDA-Approved Uses of Acetazolamide

Acetazolamide is approved by the FDA for several distinct medical conditions.

Glaucoma

One of the most common uses for acetazolamide is the treatment of glaucoma, a condition characterized by increased pressure within the eye that can lead to vision loss. It is used for various types of glaucoma, including open-angle glaucoma, secondary glaucoma, and for short-term management of acute angle-closure glaucoma before surgery. By decreasing the production of aqueous humor, the fluid inside the eye, acetazolamide effectively lowers intraocular pressure.

Acute Mountain Sickness (Altitude Sickness)

For climbers and travelers ascending to high altitudes (generally above 10,000 feet), acetazolamide is used to prevent and reduce the severity of acute mountain sickness (AMS). Symptoms of AMS include headache, nausea, dizziness, and shortness of breath. The medication works by speeding up the acclimatization process. It induces a metabolic acidosis, which stimulates breathing, improves oxygenation, and helps the body adjust to lower oxygen levels more quickly. Prophylactic treatment with acetazolamide for altitude sickness is typically started before ascent.

Edema (Fluid Retention)

Acetazolamide is used as an adjunctive treatment for edema caused by congestive heart failure or drug therapy. Its diuretic properties help the kidneys excrete excess sodium, potassium, and water, thereby reducing fluid buildup in the body. To maintain efficacy, it may be prescribed for intermittent use.

Epilepsy

As an adjunctive therapy, acetazolamide is used to help control seizures in certain types of epilepsy, such as petit mal and unlocalized seizures. The exact anticonvulsant mechanism is not fully understood but is thought to be related to the induction of metabolic acidosis in the central nervous system or its direct inhibitory effect on carbonic anhydrase in the brain.

Other Approved Uses

Other FDA-approved indications include idiopathic intracranial hypertension (also known as pseudotumor cerebri) and periodic paralysis.

Off-Label and Other Uses

Beyond its approved uses, healthcare providers may prescribe acetazolamide for other conditions based on its mechanism of action.

Some of these off-label uses include:

Central Sleep Apnea: Due to its ability to stimulate respiration.
Cerebrospinal Fluid (CSF) Leaks: To reduce the production of CSF and allow dural tears to heal.
Prevention of Methotrexate-Induced Nephrotoxicity: By alkalinizing the urine, it can help prevent kidney damage from high-dose methotrexate.

Comparison of Acetazolamide Applications


Feature	Glaucoma	Acute Mountain Sickness (AMS)	Edema	Epilepsy
Primary Goal	Reduce intraocular pressure	Accelerate acclimatization	Promote diuresis (fluid removal)	Adjunctive seizure control
Mechanism Focus	Decreases aqueous humor production	Induces metabolic acidosis, stimulating breathing	Inhibits renal carbonic anhydrase to excrete water	Acidification of the CNS and other neural effects
Treatment Duration	Long-term or pre-operative	Short-term (during ascent)	Short-term, often intermittent	Long-term (adjunctive)

Potential Side Effects and Precautions

Like all medications, acetazolamide can cause side effects. Common ones include numbness and tingling in the extremities (paresthesia), fatigue, drowsiness, loss of appetite, and changes in taste. Increased urination is also common, especially at the beginning of treatment.

Serious side effects are possible, such as metabolic acidosis, electrolyte imbalances (low potassium or sodium), kidney stones, and severe skin reactions. Acetazolamide is a sulfonamide derivative, and although rare, it can cause serious allergic reactions similar to other sulfa drugs.

It is contraindicated in patients with severe kidney or liver disease (including cirrhosis), certain electrolyte imbalances, and adrenal gland failure.

Conclusion

Acetazolamide is a medication with a broad spectrum of uses, stemming from its ability to inhibit the carbonic anhydrase enzyme. From lowering pressure in the eyes and brain to helping the body acclimatize to high altitudes and controlling seizure activity, it serves as a critical treatment for various conditions. Its effectiveness, however, must be balanced against its potential side effects and contraindications, requiring careful medical supervision.

For more detailed information, consult a healthcare professional or visit the National Library of Medicine's MedlinePlus page on Acetazolamide.

Frequently Asked Questions

Acetazolamide has several primary purposes. It is most commonly used to treat glaucoma by reducing eye pressure, to prevent and treat altitude sickness, to reduce fluid retention (edema) associated with heart failure, and as an add-on medication to control certain seizures.

Acetazolamide helps with altitude sickness by speeding up acclimatization. It makes the blood more acidic, which stimulates breathing, increases oxygen intake, and helps your body adjust more quickly to the lower oxygen levels at high altitudes.

Yes, acetazolamide has diuretic effects. It works on the kidneys to increase the excretion of water, sodium, and bicarbonate, which helps reduce fluid buildup (edema) in the body.

Acetazolamide is a sulfonamide derivative. While cross-sensitivity between sulfa antibiotics and non-antibiotic sulfonamides like acetazolamide is considered uncommon, you should inform your doctor of any sulfa allergy before taking it, as serious allergic reactions are possible.

The most common side effects include numbness and tingling in the hands and feet, fatigue, loss of appetite, changes in taste, increased urination, drowsiness, and nausea.

When administered intravenously, a reduction in intraocular pressure can occur rapidly. When taken orally, the onset of action varies depending on the formulation.

Yes, acetazolamide is a prescription medication and cannot be purchased over the counter. You must consult with a healthcare provider to determine if it is appropriate for you.