How this instrument works
Corticosteroids differ enormously in strength per milligram, so pharmacology has long expressed each drug's dose against one reference point: hydrocortisone 20 mg, chosen because it approximates the body's own daily cortisol output. Every other drug on the list carries a factor showing how many of its milligrams equal that 20 mg — cortisone 25, prednisone 5, prednisolone 5, methylprednisolone 4, triamcinolone 4, dexamethasone 0.75, betamethasone 0.6. Divide one factor by another and a dose of any listed drug converts to its anti-inflammatory match in any other.
The table is older than it looks and newer than a single paper. Meikle and Tyler measured pituitary-adrenal suppression after oral hydrocortisone, prednisone, and dexamethasone in 1977, establishing three of the eight ratios directly from human data. The remaining five — cortisone, prednisolone, methylprednisolone, triamcinolone, betamethasone — come from a widely reproduced consensus that shows up consistently across pharmacology texts and hospital formularies rather than from one study's output; treat it as the standard clinical reference rather than a single controlled trial's finding.
'Equivalent' here means equal anti-inflammatory strength alone, not equal behavior on every axis a corticosteroid touches. Mineralocorticoid activity — the sodium-retaining, fluid-holding effect mediated through a separate receptor — varies independently of the anti-inflammatory potency this table tracks. Hydrocortisone and cortisone carry meaningful mineralocorticoid activity at their listed doses; dexamethasone and betamethasone carry almost none. Two doses that match perfectly on this scale can still differ sharply in how much salt and water a patient retains.
- Enter the known dose in milligrams.
- Choose the drug you are converting from in the first menu.
- Choose the drug you are converting to in the second menu.
- Read the matching dose; the working block shows the ratio applied to the original figure.
Worked example — 20 mg hydrocortisone to dexamethasone
A patient is on 20 mg of hydrocortisone daily and the plan calls for dexamethasone instead. Hydrocortisone's factor is 20, dexamethasone's is 0.75: 20 × (0.75 ÷ 20) = 0.75 mg. A 20 mg dose shrinks to three-quarters of one milligram — a roughly 27-fold potency gap between the two drugs, gram for gram.
Run the same arithmetic in reverse and the scale flips the other way: 10 mg of dexamethasone converts back through the same ratio, 10 × (20 ÷ 0.75), to about 266.7 mg of hydrocortisone. A smaller conversion shows the middle ground — 5 mg of prednisone, factor 5, becomes 4 mg of methylprednisolone, factor 4, a far gentler adjustment than the hydrocortisone-dexamethasone pair.
Questions
Is this eight-drug table the direct output of one clinical trial?
No, and it is worth being precise about that. Meikle and Tyler's 1977 study in the American Journal of Medicine measured only three drugs directly — hydrocortisone, prednisone, and dexamethasone. The other five ratios are a long-standing consensus reference reproduced across pharmacology textbooks and hospital formularies, not a single study's measurement, though they are the values clinicians reach for as the standard.
What does 'equivalent dose' actually mean in this table?
Equal anti-inflammatory potency and nothing more. Corticosteroids act on more than one receptor system, and mineralocorticoid activity — the salt- and water-retaining effect — is not fixed to anti-inflammatory strength. Hydrocortisone retains meaningfully more sodium at its listed dose than dexamethasone does at its matching dose, a real difference this ratio does not capture.
Why is hydrocortisone the reference point rather than a stronger drug?
Because it approximates what the adrenal glands produce naturally in a day, giving the scale a physiological anchor rather than an arbitrary one. Every other factor in the table describes how many milligrams of that drug match 20 mg of hydrocortisone, which keeps the whole system tied back to normal cortisol output.
Can I use this figure to switch a patient's steroid directly?
Treat it as a starting reference, not a finished prescription. Real switches also depend on duration of action, dosing schedule, the condition being treated, and a patient's individual response — a qualified clinician weighs those alongside the raw potency ratio before changing a regimen.
Why does dexamethasone come out to such a small number of milligrams?
Because it is roughly 27 times more potent per milligram than hydrocortisone, so matching anti-inflammatory strength takes a fraction of the dose. Betamethasone sits close behind it at a factor of 0.6, while cortisone and hydrocortisone sit at the weak end of the table, needing the largest milligram figures to match the same effect.
Do these drugs all last the same length of time in the body?
No, and that is a real gap in what this table shows. Hydrocortisone and cortisone act for roughly eight to twelve hours, prednisone and methylprednisolone run intermediate at twelve to thirty-six hours, and dexamethasone and betamethasone extend beyond thirty-six hours. Two matched doses can still call for very different dosing schedules once duration is factored in.
References
- Meikle & Tyler 1977, Am J Med — original potency study (PubMed)
- StatPearls — Physiology, Glucocorticoids (NCBI Bookshelf)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.