Acetazolamide is a carbonic anhydrase inhibitor. Carbonic anhydrase is a protein in your body. Acetazolamide reduces the activity of this protein.

Acetazolamide is used to treat glaucoma and to treat and to prevent acute mountain sickness (altitude sickness). It is also used as a part of some treatment plans for congestive heart failure and seizure disorders.

Acetazolamide may also be used for purposes other than those listed in this medication guide.

Take acetazolamide exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.

Take each dose with a full glass of water.

Take acetazolamide with food if it upsets your stomach.

Store acetazolamide at room temperature away from moisture and heat.

Before taking this medication, tell your doctor if you are taking any of the following medicines:

• cyclosporine (Sandimmune). Cyclosporine may have more side effects if it is taken with acetazolamide.

• primidone (Mysoline). Primidone may not be as effective if it is taken with acetazolamide, and seizure control may be reduced.

• diflunisal (Dolobid). Diflunisal may increase both the activity and the side effects of acetazolamide.

• aspirin, salsalate (Disalcid, Salflex, Salsitab, others), choline salicylate (Arthropan), magnesium salicylate (Doan’s, Magan, Mobidin), and other aspirin-like products (salicylates). These medicines may also interact with acetazolamide, and special monitoring of your therapy may be necessary.

• lithium (Lithobid, Eskalith, others). Acetazolamide may decrease the level of lithium in your blood. Special monitoring or a dosage adjustment may be necessary.

Drugs other than those listed here may also interact with acetazolamide. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.

Use caution when driving, operating machinery, or performing other hazardous activities. Acetazolamide may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Avoid prolonged exposure to sunlight. Acetazolamide may increase the sensitivity of your skin to sunlight. Use a sunscreen and wear protective clothing when exposure to the sun is unavoidable.

Seek emergency medical attention.

Symptoms of an acetazolamide overdose are not well known, but the following symptoms might be expected: drowsiness, decreased appetite, nausea, vomiting, dizziness, numbness or tingling, shaking, and ringing in the ears.

Take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take only your next regularly scheduled dose. Do not take a double dose of this medication.

Call your doctor immediately if you experience a sore throat, fever, unusual bleeding or bruising, tingling or tremors in your hands or feet, pain in your side or groin, or a rash. These symptoms could be early signs of a serious side effect.

Use caution when driving, operating machinery, or performing other hazardous activities. Acetazolamide may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Avoid prolonged exposure to sunlight. Acetazolamide may increase the sensitivity of your skin to sunlight. Use a sunscreen and wear protective clothing when exposure to the sun is unavoidable.

Tell your doctor if you have ever had an allergic reaction to a sulfa-based drug such as sulfamethoxazole (e.g., Bactrim, Septra, Gantanol). Acetazolamide is also a sulfa-based drug, and you may have a similar reaction to it.

Before taking acetazolamide, tell your doctor if you

• are on aspirin therapy,

• have liver disease,

• have kidney disease,

• have heart disease,

• have lung disease, or

• have a hormonal disease.

You may not be able to take acetazolamide, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.

Acetazolamide is in the FDA pregnancy category C. This means that it is not known whether acetazolamide will harm an unborn baby. Do not take acetazolamide without first talking to your doctor if you are pregnant.

Acetazolamide passes into breast milk. It is not known whether acetazolamide will affect a nursing infant. Do not take acetazolamide without first talking to your doctor if you are breast-feeding a baby.

Your pharmacist has more information about acetazolamide written for health professionals that you may read.

Acetazolamide is available with a prescription generically and under the brand name Diamox . Other brand or generic formulations may also be available. Ask your pharmacist any questions you have about this medication, especially if it is new to you.

• Diamox 125 mg—round, white, scored tablets

• Diamox 250 mg—round, white, scored tablets

• Diamox Sequels 500 mg (Sustained Release)—orange capsules