Steroid Conversion Calculator

Corticosteroid equivalency tables exist because the different synthetic derivatives of cortisone vary enormously in both glucocorticoid (anti-inflammatory) potency and mineralocorticoid (sodium/water-retaining) activity, and simply matching milligram doses across drugs would produce wildly inconsistent clinical effects. Hydrocortisone, chemically identical to the body's own cortisol, is the reference point for physiologic replacement dosing (adrenal insufficiency) precisely because it retains meaningful mineralocorticoid activity, while dexamethasone has essentially none — making dexamethasone useful for suppressing inflammation (or brain edema, or as an antiemetic) without the fluid retention and hypertension risk that a mineralocorticoid-active steroid would cause at an equivalent anti-inflammatory dose. Potency ratios are anchored to prednisone 5mg as the common reference unit: hydrocortisone 20mg, methylprednisolone 4mg, and dexamethasone 0.75mg are each considered roughly equipotent to that reference for glucocorticoid effect, though these ratios describe anti-inflammatory potency only and do not account for each drug's very different half-life. Dexamethasone's biologic half-life (36-54 hours) is dramatically longer than prednisone's (12-36 hours) or hydrocortisone's (8-12 hours), so an equivalency-table conversion tells you the right anti-inflammatory dose but not automatically the right dosing frequency — a longer-acting steroid needs less frequent dosing even at an 'equivalent' daily total.

Edward Kendall and Philip Hench's isolation and characterization of cortisone at the Mayo Clinic, for which they shared the 1950 Nobel Prize in Physiology or Medicine, launched the corticosteroid era after their dramatic 1949 demonstration that cortisone injections could rapidly reverse severe rheumatoid arthritis symptoms. The clinical enthusiasm that followed quickly ran into the drug's mineralocorticoid side effects, driving a wave of pharmaceutical research through the 1950s to synthesize derivatives that preserved anti-inflammatory potency while reducing sodium retention. Prednisone (1955), prednisolone, methylprednisolone, and dexamethasone (1958) were all developed within a decade of cortisone's introduction specifically to improve this therapeutic ratio, with dexamethasone representing the extreme end of the spectrum — near-total loss of mineralocorticoid activity alongside markedly increased glucocorticoid potency and duration of action. As the number of available corticosteroids proliferated through the 1960s, clinical pharmacologists compiled comparative potency tables based on animal and clinical anti-inflammatory assays, and these equivalency ratios — refined only modestly since — have remained the standard reference used in endocrinology, rheumatology, and critical care corticosteroid dosing and conversion decisions.