Studies in the 1980s linking rapid correction of severe, chronic hyponatremia to the osmotic demyelination syndrome (ODS) led to a major controversy that eventually gave way to consensus guidelines. Efforts to limit correction to ≤8 mmol/L per day in patients at high risk of developing ODS became common practice. Recent studies have questioned these guidelines, suggesting that ODS is rare and that slow correction may increase mortality. In this review, we revisit the history of the controversy and find that these claims have persisted for four decades.