Acetazolamide: what it treats, how to take it, side effects
Last updated September 6, 2026.
**Acetazolamide is a prescription carbonic anhydrase inhibitor that lowers eye pressure and changes how your kidneys handle fluid and salts.** It reduces fluid production in your eyes and increases bicarbonate, salt, and water loss through urine. It can cause dangerous blood acidity and electrolyte changes, especially if your kidneys do not work well.
What does it treat?
You may receive acetazolamide for glaucoma, prevention or relief of altitude sickness with headache and nausea after climbing, or fluid retention caused by heart failure or medicines. It also supplements other medicines for certain seizures. For acute angle-closure glaucoma, it can temporarily lower pressure before definitive treatment.
How do you take it?
Oral forms include 125 mg and 250 mg tablets and 500 mg extended-release capsules. Adult label doses depend on your condition: open-angle glaucoma, 250 to 1,000 mg daily, divided above 250 mg; extended-release glaucoma treatment, 500 mg twice daily; altitude sickness, 500 to 1,000 mg daily divided, starting 24 to 48 hours before ascent; edema, usually 250 to 375 mg each morning with prescribed rest days; epilepsy, usually 375 to 1,000 mg daily divided. The usual upper limit for these regimens is 1,000 mg daily, but specialist regimens differ. You can take it with or without food; swallow extended-release capsules whole. Take a missed dose when remembered unless the next is nearly due; never double. Stop and call your doctor for rash or unusual bruising.
Side effects to know
- Common: You may notice tingling, more urination, altered taste, nausea, diarrhea, or reduced appetite; report new or persistent symptoms to your prescriber.
- Serious: Stop taking it and get prompt help for rash, fever with sore throat, unusual bleeding, yellow skin or eyes, or bloody urine, which can signal serious skin, blood, liver, or kidney problems. Sudden eye pain or worsening vision needs immediate eye care.
Who should not take it?
Do not take it with a known acetazolamide allergy, markedly impaired kidney or liver function, cirrhosis, low sodium or potassium, adrenal failure, or hyperchloremic acidosis. Long-term use is contraindicated in chronic noncongestive angle-closure glaucoma. Discuss sulfa allergy, kidney stones, diabetes, or impaired breathing first. Review aspirin and all other medicines. Pregnancy requires weighing benefit against fetal risk; breastfeeding requires deciding with your prescriber whether to stop nursing or the medicine. Avoid alcohol because it increases drowsiness.
When is it an emergency?
For any suspected overdose, call Poison Control at 1-800-222-1222 immediately. Warning signs include severe sleepiness, confusion, weakness, or rapid breathing. Call 911 for collapse, breathing trouble, seizures, inability to awaken, or throat swelling. Blistering skin or mouth sores require emergency care. At altitude, breathlessness at rest, confusion, or inability to walk steadily requires immediate descent and emergency help even if you took acetazolamide.
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Common questions
What is the maximum daily dose?
For altitude sickness, the label tops out at 1,000 mg daily. For open-angle glaucoma, doses above 1,000 mg generally add no benefit. Some specialist regimens differ, so follow your prescription and never increase it yourself.
Can I drink alcohol?
Avoid alcohol while taking acetazolamide. It adds to medication-related drowsiness. Do not drive if you feel sleepy or dizzy.
Can I take it during pregnancy or breastfeeding?
The label permits pregnancy use only when benefit justifies fetal risk. Animal studies found birth defects; adequate human studies are lacking. For breastfeeding, discuss whether to stop nursing or treatment based on your need for the medicine.
Do I need to take it with food?
You can take it with or without food. Food does not affect absorption of extended-release capsules. Do not crush or chew those capsules.
What happens if I take too much?
Overdose can disrupt blood salts and acidity, causing weakness, confusion, or rapid breathing. Call Poison Control at 1-800-222-1222 without waiting for symptoms. Call 911 for collapse or breathing trouble.
Which interactions matter most?
High-dose aspirin can cause severe toxicity with acetazolamide. Sodium bicarbonate increases kidney stone risk, and other carbonic anhydrase inhibitors can add adverse effects. Your prescriber must also review lithium, phenytoin, primidone, cyclosporine, and methenamine.