GC = glucocorticoid; MC = mineralocorticoid. Equivalencies apply to anti-inflammatory / immunosuppressive effects only and are approximate. They do NOT apply linearly at very high (“pulse”) doses. MC potency values vary by source (e.g., prednisone MC is cited as 0.3-0.8 depending on assay and reference); clinically, MC effects are significant for hydrocortisone/cortisone, moderate for prednisone/prednisolone, and negligible for methylprednisolone through dexamethasone. Fludrocortisone is omitted (used exclusively for MC replacement; GC ~10, MC ~125).
Conversion Method
Step
Action
Example
1
Identify the current drug and daily dose
Prednisone 40 mg/day
2
Convert to hydrocortisone equivalents current dose × (20 ÷ current equiv. dose)
40 × (20 ÷ 5) = 160 mg hydrocortisone equiv.
3
Convert to the target drug HC equiv. × (target equiv. dose ÷ 20)
160 × (0.75 ÷ 20) = 6 mg dexamethasone
Or use the shortcut: current dose × (target equiv. dose ÷ current equiv. dose). Example: 40 mg prednisone × (0.75 ÷ 5) = 6 mg dexamethasone.
Common Conversions at a Glance
From
To
Multiply by
Prednisone
Methylprednisolone
× 0.8 (5 mg pred = 4 mg methylpred)
Prednisone
Dexamethasone
× 0.15 (5 mg pred = 0.75 mg dex)
Prednisone
Hydrocortisone
× 4 (5 mg pred = 20 mg HC)
Methylprednisolone
Prednisone
× 1.25 (4 mg methylpred = 5 mg pred)
Dexamethasone
Prednisone
× 6.67 (0.75 mg dex = 5 mg pred)
Hydrocortisone
Prednisone
× 0.25 (20 mg HC = 5 mg pred)
Physiologic vs. Pharmacologic Dosing
Category
Hydrocortisone Equivalent
Prednisone Equivalent
Clinical Context
Physiologic replacement
15-25 mg/day
3.75-6.25 mg/day
Adrenal insufficiency (primary or secondary)
Stress dose (minor procedure)
50 mg IV ×1
—
Minor surgery, dental procedures in AI patients
Stress dose (major surgery / critical illness)
50 mg IV q8h (or 100 mg q8h)
—
Major surgery, septic shock (SSC: 200 mg/day IV)
Low-dose anti-inflammatory
—
5-10 mg/day
RA maintenance, PMR
Moderate immunosuppressive
—
20-40 mg/day
Acute exacerbations (COPD, asthma), ITP
High-dose immunosuppressive
—
1-2 mg/kg/day
SLE nephritis, vasculitis, transplant rejection
Pulse therapy
—
Methylpred 500-1000 mg IV daily ×3-5 d
MS relapses, severe lupus, optic neuritis. Equivalency table does NOT apply at pulse doses.
Taper Considerations
Question
Guidance
When is a taper needed?
Generally required if steroids used >3 weeks at any dose, or >1 week at ≥prednisone 20 mg/day. Short bursts (≤7-10 days, ≤40 mg/day prednisone) can usually be stopped abruptly.
Why taper?
Exogenous steroids suppress the HPA axis. Abrupt withdrawal after prolonged use risks adrenal crisis (hypotension, hypoglycemia, shock).
General approach
Reduce by 10-20% every 1-2 weeks while monitoring for symptoms of adrenal insufficiency (fatigue, nausea, hypotension, arthralgias) and disease flare.
Below physiologic range
Once prednisone reaches ~5-7.5 mg/day (physiologic equivalent), slow the taper further (1 mg decrements q2-4 wk) and consider AM cortisol or cosyntropin stimulation test to assess HPA recovery before discontinuing.
Long-acting agents
Dexamethasone causes more HPA suppression per equivalent dose due to longer biologic half-life. Consider switching to shorter-acting agent (prednisone/prednisolone) before tapering.
Key Clinical Pearls
💡
Prednisone is a prodrug: it must be hepatically converted to prednisolone (the active form). In severe liver dysfunction (cirrhosis, acute liver failure), use prednisolone or methylprednisolone instead.
💡
Mineralocorticoid effects matter: hydrocortisone and cortisone have significant MC activity (Na+ retention, K+ wasting, edema, hypertension). At high doses, consider switching to methylprednisolone or dexamethasone (near-zero MC effect) to avoid fluid overload.
💡
Dexamethasone ≠ prednisone for all indications: the equivalency table gives anti-inflammatory equivalence, but clinical trial dosing for specific conditions (e.g., dex 6 mg in RECOVERY for COVID, dex 40 mg x4 d for myeloma) is NOT derived from simple conversion. Use the protocol-specific dose.
⚠️
Steroid-induced hyperglycemia: most pronounced with intermediate-acting agents (prednisone, methylprednisolone) given as a morning dose, producing afternoon/evening BG spikes. NPH insulin dosed in the AM mirrors this pattern and is a first-line choice. Check BG even in non-diabetic patients on ≥prednisone 20 mg/day.
⚠️
Stress dosing for chronic steroid patients: any patient on ≥prednisone 5 mg/day (or equivalent) for 3+ weeks should be assumed to have HPA suppression and needs stress-dose steroids for surgery, trauma, or critical illness. Do not rely on a “normal” random cortisol.
🛑
IV-to-PO conversion: methylprednisolone IV and PO are 1:1 (bioavailability >80%). Hydrocortisone IV to PO is also 1:1. Dexamethasone IV to PO is 1:1 (near 100% oral bioavailability). Predniso(lo)ne IV formulations are less common in the US; oral bioavailability is excellent.