Glucocorticoid Equivalence Calculator

Clinical Context & Pearls

The equivalence tables give you a baseline, not a promise. Receptor affinity, protein binding and organ dysfunction all move the response, so two patients on equivalent doses will not always look equivalent. Convert, then watch the patient.

1. The 100-25-4 Equivalence Mnemonic

The bedside mnemonic for the standard potency ratios is 100 = 25 x 4. It is the one worth carrying into a resuscitation, where nobody is going to open a table:

• 100 mg of Hydrocortisone is the physiological baseline.
• 25 mg of Prednisolone is roughly the same anti-inflammatory dose.
• 4 mg of Dexamethasone is roughly the same again. (Strict pharmacological arithmetic puts it nearer 3.75 mg. The rule is taught with 4 mg, and 4 mg is what a ward uses.)

2. Mineralocorticoid Activity (Sodium Retention)

An equivalence table converts the glucocorticoid effect and says nothing at all about the mineralocorticoid one. In septic shock or an Addisonian crisis, that silence is the error that costs the patient.

• Hydrocortisone has a 1:1 ratio of glucocorticoid to mineralocorticoid effect. It is the drug of choice for primary adrenal insufficiency.
• Dexamethasone, Betamethasone and Triamcinolone have practically zero mineralocorticoid activity. Methylprednisolone has about half that of hydrocortisone, which is less than prednisolone and is not zero: the comparison table in the result carries the figure for each agent.
• Switching a patient with primary adrenal insufficiency from Hydrocortisone to Dexamethasone removes the mineralocorticoid cover, and the blood pressure can fall from sodium wasting unless Fludrocortisone is added. In secondary or glucocorticoid-induced adrenal insufficiency the zona glomerulosa still works, and the 2024 ESE and Endocrine Society joint guideline recommends against fludrocortisone. Which kind of adrenal insufficiency this is decides the answer.

3. Biological Half-Life & Dosing Frequency

You cannot convert a long-acting steroid to a short-acting steroid and maintain the same dosing frequency.

• Short-acting (8-12 hours): Hydrocortisone, Cortisone. Must be dosed BID to QID.
• Intermediate-acting (12-36 hours): Prednisolone, Methylprednisolone, Deflazacort. Can be dosed OD or BID.
• Long-acting (36-72 hours): Dexamethasone, Betamethasone. Dosed OD.

4. HPA Axis Suppression & Tapering

Any patient on a dose greater than the physiological equivalent of 5 mg Prednisolone per day for more than 3 weeks must be assumed to have Hypothalamic-Pituitary-Adrenal (HPA) axis suppression.

• Abrupt cessation will cause acute secondary adrenal insufficiency.
• Above 7.5 mg of Prednisolone equivalent, the disease activity sets the pace of the taper. Below it, the adrenal glands do: slow the reduction to something like a 1 mg drop every 1-2 weeks, and give the axis the time it needs to restart its own cortisol.