Why convert between corticosteroids?
Corticosteroids such as prednisone, methylprednisolone and dexamethasone treat asthma, arthritis, autoimmune diseases, allergic reactions and many other conditions. Switching from one to another, for example from IV methylprednisolone in hospital to oral prednisone at home, requires an equivalent dose.
Equivalent doses
These doses have about the same anti-inflammatory (glucocorticoid) effect:
| Steroid | Equivalent dose | Relative potency | Duration of action |
|---|---|---|---|
| Cortisone | 25 mg | 0.8 | Short (8–12 h) |
| Hydrocortisone | 20 mg | 1 | Short (8–12 h) |
| Prednisone | 5 mg | 4 | Intermediate (12–36 h) |
| Prednisolone | 5 mg | 4 | Intermediate |
| Methylprednisolone | 4 mg | 5 | Intermediate |
| Triamcinolone | 4 mg | 5 | Intermediate |
| Dexamethasone | 0.75 mg | 25–30 | Long (36–72 h) |
| Betamethasone | 0.6–0.75 mg | 25–30 | Long |
Worked example
A patient takes 20 mg of prednisone a day:
- 20 ÷ 5 = 4 “units”.
- Methylprednisolone: 4 × 4 = 16 mg.
- Hydrocortisone: 4 × 20 = 80 mg.
- Dexamethasone: 4 × 0.75 = 3 mg.
What the table does not capture
- Mineralocorticoid effect (salt and water retention): strong with hydrocortisone and fludrocortisone, almost absent with dexamethasone. For adrenal insufficiency, hydrocortisone is preferred for this reason.
- Duration: long-acting dexamethasone suppresses the adrenal glands more for the same equivalent dose.
- Route: inhaled, topical and joint injections act mainly locally, and these equivalents do not apply.
Adrenal suppression and tapering
Taking more than about 7.5 mg of prednisone equivalent per day for more than 3 weeks can suppress the body’s own cortisol production. Stopping suddenly can then cause fatigue, low blood pressure and, rarely, an adrenal crisis. Doses are usually tapered gradually, and people on long-term steroids may need extra doses during illness or surgery (“stress dosing”).
Side effects to watch
High blood sugar, raised blood pressure, mood and sleep changes, increased appetite, bone loss and a higher risk of infection are common with longer courses. Taking the dose in the morning reduces sleep problems.
Safety
This calculator gives approximate equivalents for educational purposes. Dose changes should always be decided with the prescriber or a pharmacist.
This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.