Section 02 · Monograph
Acetazolamide
Reviewed Nov 2026FDA label
DiamoxCarbonic anhydrase inhibitor
- Forms
- Tab: 125, 250mg | ER cap: 500mg | IV: 500mg vial
- Dose
- IIH: 1-4g/day divided | Episodic ataxia: 250-1000mg/day
- MOA
- ↓CSF production; metabolic acidosis
Indications
- Glaucoma, adjunctive treatment of epilepsy, edema, acute mountain sicknessFDA-labeled
Off-Label Uses
- Idiopathic intracranial hypertension (first-line medical therapy)Off-label
- Episodic ataxia type 2Off-label
Mechanism of Action
- Carbonic anhydrase inhibitor that reduces CSF production and causes mild metabolic acidosis, lowering intracranial pressure; anticonvulsant effect via CO2 accumulation
Full Dosing
Adult / usual
- IIH: start 500mg BID and titrate toward 1-4g/day divided (IIH Treatment Trial mean about 2.5g/day), combined with weight loss and visual monitoring
- Episodic ataxia type 2: 250-1000mg/day divided
- ER capsule 500mg BID; injection 500mg vial for IV use
Contraindications
- Hypersensitivity to acetazolamide or sulfonamides
- Hepatic insufficiency or cirrhosis; adrenocortical insufficiency
- Hyponatremia, hypokalemia, hyperchloremic acidosis
- Long-term use in chronic non-congestive angle-closure glaucoma
Drug Interactions
- Topiramate and zonisamide: additive metabolic acidosis and kidney stone risk
- High-dose aspirin: salicylate toxicity
- Alters levels of lithium, phenytoin and carbamazepine; raises cyclosporine
Adverse Effects
- Paresthesias and taste alteration (carbonated drinks taste flat)
- Fatigue, nausea, polyuria
- Metabolic acidosis, hypokalemia, kidney stones
- Rare: Stevens-Johnson syndrome, aplastic anemia (sulfonamide class)
Monitoring Parameters
- Basic metabolic panel (bicarbonate, potassium) and CBC periodically
- Visual fields and papilledema (IIH)
- Weight
Pregnancy & Lactation
- Teratogenic potential in animals; in IIH pregnancy use only if benefit justifies and generally avoid in the first trimester
- Small amounts in milk