Corticosteroid dose equivalence questions show up constantly on Residência Médica, ENAMED, and ENARE exams, and the calculation only works if you know the reference ratios cold. This guide walks through the exact steps to convert one glucocorticoid to another, with the standard equivalence table you need memorized before test day.
- Dose equivalente corticoide conversion rests on a fixed ratio table: 20mg hydrocortisone = 5mg prednisone = 4mg methylprednisolone = 0.75mg dexamethasone.
- Dexamethasone and betamethasone carry roughly 25-30x the anti-inflammatory potency of hydrocortisone but almost zero mineralocorticoid activity.
- Prednisone-to-dexamethasone conversion errors are a top-missed question type on Residência Médica exams in 2026 — verify with the ratio, not memory alone.
- Duration class (short, intermediate, long-acting) changes dosing frequency even when the anti-inflammatory dose is technically equivalent.
Why this matters
Glucocorticoid switching happens in real practice for tapering schedules, adrenal insufficiency workups, and side-effect management — and exam writers know it's a high-yield way to test pharmacology reasoning in one question. Get the ratio wrong on a taper calculation and a patient goes into withdrawal; get it wrong on ENARE and you lose a point you shouldn't have.
The math itself is simple ratio work. The failure point is almost always a memorized number that's slightly off, or forgetting that potency ratio and mineralocorticoid activity are two separate variables. Both show up separately on exam stems.
What you'll need
- The standard glucocorticoid equivalence table (below)
- The starting drug name and dose in milligrams
- The target drug you're converting to
- Awareness of duration class: short-acting, intermediate-acting, or long-acting
- A note on mineralocorticoid activity if the question involves adrenal insufficiency or Addison's disease
- Practice questions to drill the conversion until it's automatic — this is exactly the kind of pharmacology item that appears repeatedly across MedApex's exam-style question bank for Residência Médica and ENAMED prep
The steps
1. Identify the reference drug and its dose
Every conversion starts from a known dose of a known drug — usually stated directly in the exam stem, for example "patient on 40mg prednisone daily." Write this down as your anchor value before touching any ratio. Skipping this step is why students convert in the wrong direction under time pressure.
2. Pull the correct equivalence dose from the table
Memorize this exact set of equivalent doses, all expressed as anti-inflammatory equivalents:
| Corticosteroid | Equivalent dose | Duration class | Mineralocorticoid activity |
|---|---|---|---|
| Cortisone acetate | 25 mg | Short (8-12h) | High |
| Hydrocortisone | 20 mg | Short (8-12h) | High |
| Prednisone | 5 mg | Intermediate (12-36h) | Low |
| Prednisolone | 5 mg | Intermediate (12-36h) | Low |
| Methylprednisolone | 4 mg | Intermediate (12-36h) | Minimal |
| Triamcinolone | 4 mg | Intermediate (12-36h) | None |
| Dexamethasone | 0.75 mg | Long (36-72h) | None |
| Betamethasone | 0.6 mg | Long (36-72h) | None |
This table is the entire foundation of dose equivalente corticoide calculations. Every other step is just applying it correctly.
3. Set up the conversion ratio
Divide the starting dose by its equivalence value, then multiply by the target drug's equivalence value. For 40mg of prednisone converting to dexamethasone: 40 ÷ 5 = 8, then 8 × 0.75mg = 6mg dexamethasone. That's the full calculation — no shortcuts, no rounding until the final answer.
Common mistake: dividing by the wrong equivalence value because the ratio was memorized backward. Prednisone's 5mg equivalent is smaller than hydrocortisone's 20mg because prednisone is more potent per milligram — students who forget this invert the whole calculation.
4. Adjust for mineralocorticoid activity when the case calls for it
Anti-inflammatory dose equivalence and mineralocorticoid (sodium-retaining) activity are separate axes. Hydrocortisone and cortisone carry meaningful mineralocorticoid activity; dexamethasone and betamethasone carry essentially none. If the clinical stem involves adrenal insufficiency management, you may need fludrocortisone added on top of the glucocorticoid dose — the equivalence table alone won't cover that layer.
5. Match duration class to the dosing schedule
Short-acting drugs (hydrocortisone, cortisone) need dosing every 8-12 hours. Intermediate agents (prednisone, prednisolone, methylprednisolone, triamcinolone) run every 12-36 hours. Long-acting agents (dexamethasone, betamethasone) can stretch to 36-72 hours. An equivalent total daily dose split incorrectly across dosing intervals is a separate exam trap from the equivalence math itself.
Expected outcome: you should be able to state both the converted milligram dose and the correct dosing frequency for the new drug, not just the number.
6. Sanity-check the direction of the conversion
If you're converting from a weaker drug (higher mg per equivalent dose, like hydrocortisone) to a stronger one (lower mg per equivalent dose, like dexamethasone), the final number should be smaller. If your answer went up in milligrams during that conversion, you made an arithmetic or table error — go back to step 3.
7. Drill the conversion against timed practice questions
One worked example doesn't build exam speed. Corticosteroid equivalence questions repeat with different starting drugs and doses across Residência Médica, ENAMED, and ENARE cycles, and the fastest way to lock the ratio table into memory is spaced repetition against real exam-style stems — which is the exact mechanism behind MedApex's flashcard and question bank for 2026 exam prep.
“If your converted dose went up in milligrams while switching to a more potent corticosteroid, the calculation is wrong before you even check the table.”
Drill corticosteroid conversions before exam day
Practice pharmacology questions built for Residência Médica, ENAMED, and ENARE.
Troubleshooting
Problem: the answer comes out as a decimal that doesn't match any answer choice. Re-check which drug is the reference and which is the target — you may have divided by the target's equivalence value instead of the starting drug's.
Problem: you're not sure whether to include mineralocorticoid effect in the answer. Only adjust for it if the stem mentions adrenal insufficiency, hyponatremia, hypotension, or a similar sodium/volume-related clinical detail. Pure anti-inflammatory dosing questions ignore it entirely.
Problem: you keep confusing prednisone and prednisolone doses. They share the same 5mg equivalence and are functionally interchangeable in most exam contexts — the distinction only matters in hepatic impairment, where prednisone (a prodrug) converts poorly to active prednisolone.
Problem: dexamethasone and betamethasone doses feel too small to be right. They are supposed to be. Their potency is roughly 25-30 times hydrocortisone's, so equivalent doses sit under 1mg. This is the single most common source of "that can't be right" hesitation on exam day — trust the table.
Problem: you're running out of time on multi-step conversion questions. Memorize the table cold rather than re-deriving ratios from potency multipliers during the exam. Speed on this question type comes from recall, not recalculation.
Tools and resources
- The equivalence table above, kept as a single reference card
- A basic calculator for the ratio arithmetic — mental math works too once the table is memorized
- Spaced-repetition flashcards covering pharmacology conversions, available through MedApex's question bank for Residência Médica, ENAMED, and ENARE candidates
- Practice sets that mix drug names, so you're not always converting from the same starting point
What to do next
Once the equivalence table is memorized, the next skill is applying it inside a full clinical vignette — where the corticosteroid conversion is one step buried inside a longer stem about tapering, adrenal suppression, or steroid-induced hyperglycemia. That's where most points are actually lost in 2026 exam cycles, not on the isolated conversion question itself.
FAQ
What is dose equivalente corticoide and why does it matter for exams?
Dose equivalente corticoide is the anti-inflammatory equivalence ratio between different corticosteroid drugs, letting you convert a dose of one glucocorticoid to another. It matters because Residência Médica, ENAMED, and ENARE exams test this conversion directly, and clinical taper schedules depend on getting it right.
How much prednisone equals dexamethasone?
5mg of prednisone equals 0.75mg of dexamethasone based on standard anti-inflammatory equivalence ratios. Scale proportionally for any prednisone dose: 40mg prednisone equals 6mg dexamethasone.
Is hydrocortisone or prednisone more potent per milligram?
Prednisone is more potent per milligram than hydrocortisone. The equivalence table shows 20mg hydrocortisone equals only 5mg prednisone, meaning prednisone is roughly four times as potent by weight.
Which corticosteroid has the least mineralocorticoid activity?
Dexamethasone and betamethasone have essentially no mineralocorticoid activity. Hydrocortisone and cortisone acetate carry the highest mineralocorticoid activity among the standard glucocorticoids.
How long does dexamethasone last compared to prednisone?
Dexamethasone is long-acting with a biological half-life of 36-72 hours, while prednisone is intermediate-acting at 12-36 hours. This difference changes dosing frequency even at an equivalent anti-inflammatory dose.
Can prednisone and prednisolone doses be used interchangeably?
Yes, prednisone and prednisolone share the same 5mg equivalence dose and are interchangeable in most cases. The exception is significant hepatic impairment, since prednisone is a prodrug that converts to active prednisolone in the liver.
What's the fastest way to memorize corticosteroid equivalence for exams?
Spaced repetition against real exam-style questions is faster than memorizing the table in isolation, because it forces recall under the same conditions as the actual exam. Flashcard systems built around Residência Médica and ENAMED question patterns speed this up further.
Why do dexamethasone doses look so much smaller than prednisone doses?
Dexamethasone is roughly 25-30 times more potent than hydrocortisone per milligram, so its equivalent doses sit under 1mg. This is expected and correct, not a calculation error.
One last thing
The detail most students skip: mineralocorticoid activity and anti-inflammatory potency don't move together in a straight line. Methylprednisolone and triamcinolone share the same 4mg anti-inflammatory equivalence, but methylprednisolone retains a trace of mineralocorticoid activity while triamcinolone has none — a distinction exam writers use specifically to separate students who memorized the table from students who understood it.
