Steroid Conversion Calculator
Convert between equivalent doses of corticosteroids (prednisone, dexamethasone, hydrocortisone).
Reviewed by Rahul Singh, Health & Wellness Specialist
Formula
Target Dose = (Source Dose / Source Equivalent) x Target Equivalent
The conversion divides the source dose by its standard equivalent dose (relative to 5 mg prednisone) to determine how many equivalent units are present, then multiplies by the target steroid equivalent dose. For example, 40 mg prednisone = 8 equivalent units x 0.75 mg dexamethasone = 6 mg dexamethasone.
Worked Examples
Example 1: Prednisone to Dexamethasone Conversion
Problem:A patient on prednisone 40 mg daily needs to switch to dexamethasone. What is the equivalent dose?
Solution:Prednisone equivalent dose: 5 mg\nDexamethasone equivalent dose: 0.75 mg\nConversion: (40 / 5) x 0.75 = 6 mg dexamethasone\nRatio: prednisone 40 mg = dexamethasone 6 mg\nNote: Dexamethasone has no mineralocorticoid activity\nDuration: Long-acting (36-54 hr biologic half-life)
Result:Dexamethasone 6 mg daily (equivalent to prednisone 40 mg)
Example 2: Methylprednisolone IV to Prednisone PO Taper
Problem:A patient received methylprednisolone 125 mg IV for an asthma exacerbation. What oral prednisone dose is equivalent for step-down?
Solution:Methylprednisolone equivalent dose: 4 mg\nPrednisone equivalent dose: 5 mg\nConversion: (125 / 4) x 5 = 156.25 mg prednisone\nRound to 160 mg (or start at a lower taper dose)\nTypical step-down: prednisone 40-60 mg PO daily\nwith taper over 5-10 days for asthma
Result:Equivalent: prednisone 156 mg (clinical taper typically starts at 40-60 mg)
Frequently Asked Questions
How should steroid doses be adjusted during physiologic stress?
Patients on chronic corticosteroids or with known adrenal suppression require stress dose steroids during periods of physiologic stress because their suppressed adrenal glands cannot mount an appropriate cortisol response. For minor stress such as a mild febrile illness, doubling the usual daily dose for 2 to 3 days is typically sufficient. For moderate stress like uncomplicated surgery under general anesthesia, hydrocortisone 50 mg IV before induction followed by 25 mg every 8 hours for 24 to 48 hours is a standard protocol. For major stress including sepsis, major surgery, or critical illness, hydrocortisone 100 mg IV bolus followed by 50 mg every 8 hours is recommended, with tapering over several days as the stress resolves. Failure to provide adequate stress dosing can result in adrenal crisis with hypotension, shock, and potentially death.
What are the most common unit conversion mistakes?
Common errors include confusing fluid ounces with weight ounces, mixing up miles and nautical miles, forgetting that UK and US gallons differ (UK is 20% larger), using the wrong temperature formula, and not accounting for the difference between troy and avoirdupois ounces.
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy