Acetazolamide use in idiopathic intracranial hypertension: a real-world cohort study of side effects.

BACKGROUND: Acetazolamide is an off-label-first-line treatment for idiopathic intracranial hypertension (IIH) used at doses four times higher than approved and with high discontinuation rates due to side effects. This research assesses prescribing patterns and tolerability by dosage, papilledema severity, and potassium supplementation. METHODS: Within a prospective cohort of newly diagnosed IIH patients from two tertiary headache centers, acetazolamide-related side effects were retrospectively registered until tapering due to intolerance or papilledema remission. Side effects were categorized by dose (>0-1000 mg, >1000-2000 mg, >2000-3000 mg, >3000-4000 mg). Potassium and bicarbonate supplementation were evaluated. RESULTS: Among 139 acetazolamide-treated patients (97% female, median age 28 years (IQR 25-36), median BMI 35 (IQR 30-39)) side effects were noted in 99%, but led to dosage reduction or discontinuation in 22%. Acroparesthesia (85%) was most frequent followed by dysgeusia (51%), fatigue (46%), nausea/vomiting (34%), and tinnitus, dizziness, and cognitive symptoms (25% each). Serious adverse events included liver impairment (n = 1), kidney stones (n = 3), hearing loss (n = 1) and pulmonary embolism (n = 1). Potassium supplementation yielded fewer dosage-limiting side effects (p = 0.02), and bicarbonate alleviated metabolic acidosis symptoms in 67% of 12 patients. CONCLUSION: Side effects are near-universal but tolerable. Further research is needed whether potassium and bicarbonate supplementation improves acetazolamide tolerability and adherence.