There is no consistent evidence that IV high-dose vitamin C therapy is more harmful than placebo in double-blind randomized controlled trials. However, reports of oxalate nephropathy, hypernatremia, glucometer error, and hemolysis in glucose-6-phosphate dehydrogenase deficiency patients warrant specific monitoring.

We identified 8,149 reports, of which 650 full text were assessed for eligibility, leaving 74 eligible studies.

In these studies, 2,801 participants received high-dose vitamin C at a median (interquartile range) dose of 22.5 g/d (8.25–63.75 g/d), 455 mg/kg/d (260–925 mg/kg/d), or 70 g/m2/d (50–90 g/m2/d); and 932 or more adverse events were reported.

Among nine double-blind randomized controlled trials (2,310 patients), adverse events were reported in three studies with an event rate per patient for high-dose vitamin C identical to placebo group in one study, numerically lower in one study, and numerically higher in one study.

Read More