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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Carbonic Anhydrase Inhibitor [EPC]
Acetazolamide is a potent carbonic anhydrase inhibitor used to treat glaucoma, altitude sickness, and certain types of seizures. It works by reducing fluid pressure and adjusting electrolyte balance in the body.
Name
Acetazolamide
Raw Name
ACETAZOLAMIDE
Category
Carbonic Anhydrase Inhibitor [EPC]
Drug Count
3
Variant Count
75
Last Verified
February 17, 2026
RxCUI
562524, 197304, 197303, 307702
UNII
O3FX965V0I, 429ZT169UH
About Acetazolamide
Acetazolamide is a potent carbonic anhydrase inhibitor used to treat glaucoma, altitude sickness, and certain types of seizures. It works by reducing fluid pressure and adjusting electrolyte balance in the body.
Detailed information about Acetazolamide
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Acetazolamide.
To understand how acetazolamide works, one must understand the role of the enzyme carbonic anhydrase. This enzyme is responsible for the rapid conversion of carbon dioxide and water into bicarbonate and hydrogen ions. By inhibiting this enzyme, acetazolamide disrupts the chemical equilibrium necessary for several physiological processes. In the eyes, this inhibition reduces the rate of aqueous humor secretion, which effectively lowers intraocular pressure (the pressure inside the eye). This is critical for patients with glaucoma, where high pressure can damage the optic nerve.
In the kidneys, the inhibition of carbonic anhydrase leads to a 'bicarbonate diuresis.' This means the body excretes more bicarbonate, along with sodium, potassium, and water. This process results in a mild metabolic acidosis (a slightly more acidic blood pH). While this might sound concerning, this controlled acidity is actually therapeutic for patients with altitude sickness. The increased acidity of the blood stimulates the respiratory centers in the brain, encouraging deeper and more frequent breathing, which improves oxygenation at high altitudes. Furthermore, in the central nervous system, the inhibition of the enzyme in the choroid plexus reduces the formation of cerebrospinal fluid, which is why healthcare providers often use it to treat conditions involving increased intracranial pressure.
The pharmacokinetic behavior of acetazolamide is well-documented and predictable, which allows for precise dosing by medical professionals.
Acetazolamide is FDA-approved for several distinct clinical indications:
Acetazolamide is available in several formulations to meet different clinical needs:
> Important: Only your healthcare provider can determine if Acetazolamide is right for your specific condition. The choice of formulation and dosage will depend on your medical history and the severity of your symptoms.
The dosage of acetazolamide varies significantly based on the condition being treated. Your healthcare provider will determine the most appropriate dose for you.
Acetazolamide is used in children, but the dosage must be strictly calculated by a pediatrician based on the child's weight.
Because acetazolamide is cleared entirely by the kidneys, patients with reduced kidney function require lower doses. If the Glomerular Filtration Rate (GFR) is between 10-50 mL/min, the dosing interval is typically extended to every 12 hours. If the GFR is less than 10 mL/min, the medication is generally avoided.
Acetazolamide should be used with extreme caution in patients with liver disease. It can increase the risk of hepatic encephalopathy (brain dysfunction due to liver failure) because it reduces the clearance of ammonia.
Older adults often have decreased renal function and may be more sensitive to the electrolyte-depleting effects of the drug. Healthcare providers usually start at the lower end of the dosing range and monitor kidney function closely.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your regular schedule. Do not double the dose to catch up.
Signs of overdose may include extreme drowsiness, tingling sensations (paresthesia), nausea, dizziness, and signs of electrolyte imbalance such as muscle weakness or confusion. If an overdose is suspected, contact a poison control center or seek emergency medical attention immediately. Treatment is generally supportive, focusing on restoring electrolyte and fluid balance.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop the medication without medical guidance, as this could lead to a rebound increase in eye pressure or seizure activity.
Acetazolamide is generally well-tolerated, but its unique mechanism of action leads to several predictable side effects. The most frequently reported side effect is paresthesia, which patients often describe as a 'pins and needles' tingling sensation in the fingers, toes, and sometimes around the mouth. This is due to the drug's effect on the nerves and electrolyte balance.
Another very common effect is polyuria (increased urination). Because the drug acts as a mild diuretic, you will likely find yourself needing to use the bathroom more frequently, especially during the first few days of treatment. Additionally, many patients report a distortion of taste (dysgeusia), specifically when consuming carbonated beverages. Sodas and beer may taste 'flat' or metallic because the drug inhibits the carbonic anhydrase enzyme in the taste buds, which is required to perceive the 'sting' of carbonation.
> Warning: Stop taking Acetazolamide and call your doctor immediately if you experience any of these serious symptoms:
With prolonged use, the risk of developing chronic metabolic acidosis increases. This can lead to bone demineralization (osteomalacia) in some patients because the body uses bone minerals to buffer the excess acid. Long-term use also necessitates regular monitoring of blood counts and electrolyte levels to ensure that the medication is not causing silent damage to the bone marrow or kidneys.
There are currently no FDA black box warnings for acetazolamide. However, its status as a sulfonamide derivative means it carries significant warnings regarding potential severe skin and hematologic (blood) reactions that are common to the sulfa drug class.
Report any unusual symptoms to your healthcare provider. Even mild side effects should be discussed if they become bothersome or interfere with your daily activities.
Acetazolamide is a powerful medication that affects the entire body's acid-base balance. It is vital to understand that while it is effective, it requires careful medical supervision. Patients with a known allergy to sulfonamides (sulfa drugs) should be extremely cautious, as there is a risk of cross-reactivity. If you have ever had a severe reaction to a sulfa antibiotic, you must inform your doctor before starting acetazolamide.
No FDA black box warnings for Acetazolamide. However, the FDA does emphasize the risk of severe sulfonamide-type reactions, including Stevens-Johnson Syndrome.
Your healthcare provider will likely require periodic laboratory tests to ensure the medication is safe for you. These typically include:
Acetazolamide can cause drowsiness, dizziness, and blurred vision. You should not drive or operate heavy machinery until you know how the medication affects you. These effects may be worsened if you are also taking other sedating medications.
Alcohol should be consumed with caution. Alcohol can increase the risk of dizziness and dehydration, both of which are already potential side effects of acetazolamide. Furthermore, since acetazolamide changes the taste of carbonated beverages, many alcoholic drinks (like beer or sparkling wine) may taste unpleasant.
For patients taking acetazolamide for epilepsy or glaucoma, stopping the drug suddenly can cause a 'rebound' effect. In glaucoma, this could mean a sudden, dangerous spike in eye pressure. In epilepsy, it could trigger a seizure. Always taper the medication under the direct supervision of your healthcare provider.
> Important: Discuss all your medical conditions, especially lung disease, kidney disease, and liver disease, with your healthcare provider before starting Acetazolamide.
There are certain medications that should never be used alongside acetazolamide due to the risk of severe toxicity:
Acetazolamide can interfere with several laboratory tests:
For each major interaction, the mechanism usually involves either a change in the pH of the blood or urine, or a competition for renal excretion. The clinical consequence is often an increase in drug toxicity or a failure of the therapeutic effect.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including over-the-counter pain relievers like aspirin or ibuprofen.
Acetazolamide must NEVER be used in the following circumstances:
Conditions requiring a careful risk-benefit analysis by a physician include:
Patients who have a documented severe allergy to sulfonamides (such as Bactrim, Septra, or certain sulfonylureas) are at a high risk of cross-sensitivity. While the chemical structure of acetazolamide is slightly different from sulfa antibiotics, the risk of a life-threatening allergic reaction is high enough that it is generally avoided in these patients.
> Important: Your healthcare provider will evaluate your complete medical history, including any history of electrolyte imbalances or lung disease, before prescribing Acetazolamide.
Acetazolamide is classified as FDA Pregnancy Category C. This means that animal studies have shown an adverse effect on the fetus (specifically limb defects in rodents), but there are no adequate and well-controlled studies in humans. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is generally avoided during the first trimester when organ development is most critical. If you are planning a pregnancy or become pregnant while taking this drug, notify your doctor immediately.
Acetazolamide is excreted into human breast milk in small amounts. While the levels are generally considered low, there is a theoretical risk of metabolic effects on the nursing infant. The American Academy of Pediatrics considers it usually compatible with breastfeeding, but the infant should be monitored for adequate weight gain and any signs of lethargy or diarrhea. Always consult your pediatrician before breastfeeding while on this medication.
Acetazolamide is approved for use in children for the treatment of glaucoma and epilepsy. However, long-term use in children can lead to chronic metabolic acidosis, which has been associated with growth retardation. Pediatricians will monitor a child's height and weight closely. It is not generally recommended for altitude sickness in young children unless specifically directed by a specialist in high-altitude medicine.
Patients over the age of 65 are at a higher risk of side effects. Age-related declines in kidney function mean the drug stays in the body longer. Elderly patients are also more susceptible to falling due to the dizziness or confusion the drug can cause. Polypharmacy (taking multiple medications) is common in this age group, increasing the risk of drug-drug interactions, particularly with heart medications and diuretics.
In patients with mild to moderate renal impairment, the dose must be reduced. In patients with a GFR less than 10 mL/min, the drug is contraindicated. Regular monitoring of serum creatinine and BUN (Blood Urea Nitrogen) is essential for these patients to prevent systemic toxicity.
Acetazolamide is contraindicated in patients with marked liver disease or cirrhosis. The drug's ability to increase blood ammonia levels can precipitate hepatic encephalopathy, a condition where toxins build up in the blood and affect brain function, leading to confusion, tremors, or coma.
> Important: Special populations require individualized medical assessment. Never share your medication with others, especially those in these high-risk groups.
Acetazolamide is a potent inhibitor of the enzyme carbonic anhydrase (CA). This enzyme is a zinc-metalloprotein that catalyzes the reversible reaction involving the hydration of carbon dioxide and the dehydration of carbonic acid. By binding to the zinc atom at the active site of the enzyme, acetazolamide prevents this reaction.
In the proximal tubule of the kidney, this inhibition prevents the reabsorption of bicarbonate (HCO3-). As bicarbonate stays in the urine, it carries sodium and water with it, leading to diuresis. In the ciliary body of the eye, the inhibition of CA reduces the secretion of aqueous humor by approximately 50% to 60%. In the central nervous system, it slows the rate of cerebrospinal fluid production and increases the CO2 tension in the brain, which raises the seizure threshold.
| Parameter | Value |
|---|---|
| Bioavailability | 90% - 100% |
| Protein Binding | 90% - 95% (Albumin) |
| Half-life | 2 - 6 hours |
| Tmax | 2 - 4 hours (Tablets) |
| Metabolism | None (Excreted Unchanged) |
| Excretion | Renal 90% - 100% |
Acetazolamide belongs to the Carbonic Anhydrase Inhibitor [EPC] class. Related medications include methazolamide (oral) and topical agents like dorzolamide and brinzolamide, which are used specifically as eye drops for glaucoma.
Medications containing this ingredient
Common questions about Acetazolamide
Acetazolamide is primarily used to treat glaucoma by reducing the pressure inside the eye. It is also a key medication for preventing and treating altitude sickness, as it helps the body adjust to lower oxygen levels by stimulating breathing. Additionally, it is used as an add-on treatment for certain types of epilepsy and to reduce fluid retention (edema) in patients with congestive heart failure. Some doctors also prescribe it off-label for idiopathic intracranial hypertension. Always use this medication only for the specific condition your doctor has diagnosed.
The most common side effects include a tingling or 'pins and needles' sensation in the hands and feet, known as paresthesia. Many patients also experience increased urination because the drug acts as a mild diuretic. A unique side effect is a change in taste, where carbonated drinks like soda or beer may taste flat or metallic. Other common issues include nausea, loss of appetite, and mild drowsiness. Most of these effects are temporary and subside as your body adjusts to the medication.
It is generally advised to limit or avoid alcohol while taking acetazolamide. Alcohol can worsen side effects like dizziness, drowsiness, and lightheadedness. Because acetazolamide can cause dehydration, and alcohol is also a diuretic, the combination increases the risk of severe dehydration and electrolyte imbalances. Furthermore, the taste distortion caused by the drug may make many alcoholic beverages taste unpleasant. Discuss your alcohol consumption habits with your doctor before starting this medication.
Acetazolamide is classified as Pregnancy Category C, meaning its safety in humans has not been fully established. Animal studies have shown that high doses can cause birth defects, particularly in the limbs. Therefore, it is typically only used during pregnancy if the potential benefits to the mother clearly outweigh the risks to the fetus. It is especially avoided during the first trimester. If you are pregnant or planning to become pregnant, your healthcare provider will help you weigh the risks and benefits of alternative treatments.
The time it takes for acetazolamide to work depends on the condition being treated. For lowering eye pressure in glaucoma, it typically begins working within 1 to 1.5 hours, with the maximum effect occurring around 2 to 4 hours. For altitude sickness, it is recommended to start the drug 24 to 48 hours before your ascent to allow it to begin adjusting your blood chemistry. For fluid retention, the diuretic effect usually begins within 2 hours. Always follow the specific timeline provided by your healthcare professional.
You should not stop taking acetazolamide suddenly without consulting your doctor, especially if you are taking it for glaucoma or epilepsy. Abruptly stopping the medication can cause a 'rebound' effect, leading to a sudden and dangerous increase in eye pressure or an increase in the frequency of seizures. If you need to stop the medication, your doctor will usually provide a schedule to taper your dose gradually. Always keep enough medication on hand so you do not run out unexpectedly.
If you miss a dose, take it as soon as you remember. If it is nearly time for your next scheduled dose, skip the missed one and continue with your regular dosing schedule. Never take two doses at once to make up for a missed one, as this can increase the risk of side effects like severe tingling or stomach upset. If you frequently miss doses, consider using a pill organizer or setting a phone alarm. Consistency is key to maintaining the drug's effectiveness, especially for glaucoma and seizure control.
Acetazolamide is more likely to cause weight loss rather than weight gain. Because it is a diuretic, it causes the body to lose water weight initially. Additionally, many patients experience a loss of appetite (anorexia) or nausea, which can lead to reduced calorie intake and subsequent weight loss. If you notice a sudden, significant increase in weight while taking this drug, it could be a sign that your underlying condition, such as heart failure, is worsening. Contact your doctor if you experience rapid weight changes.
Acetazolamide has several significant drug interactions that require careful management. It should never be taken with high doses of aspirin, as this can lead to life-threatening toxicity. It can also interact with lithium, heart medications like digoxin, and other diuretics. Because it is a sulfa-based drug, it may interact with other sulfonamides. Always provide your doctor with a complete list of all prescription drugs, over-the-counter medicines, and herbal supplements you are taking to ensure your safety.
Yes, acetazolamide is widely available as a generic medication in both tablet and extended-release capsule forms. The generic versions are bioequivalent to the brand-name drug Diamox, meaning they have the same active ingredient and work the same way in the body. Generic versions are typically much more affordable than the brand-name equivalents. Most insurance plans cover the generic version of acetazolamide. Consult your pharmacist to ensure you are receiving the correct formulation prescribed by your doctor.