What is the equivalent dose of prednisolone (corticosteroid) when switching from intravenous (IV) hydrocortisone (corticosteroid)?

Hydrocortisone to Prednisolone Conversion

When switching from intravenous hydrocortisone to oral prednisolone, use a 4:1 conversion ratio—20 mg hydrocortisone equals 5 mg prednisolone. 1, 2

Standard Conversion Ratios

The established glucocorticoid equivalency is based on anti-inflammatory potency:

• Hydrocortisone 20 mg = Prednisolone 5 mg 1, 2
• Prednisolone is approximately 4 times more potent than hydrocortisone 1
• This 4:1 ratio applies to both oral and intravenous administration 2

Clinical Application by Scenario

Postoperative Transition from IV Hydrocortisone

When transitioning patients from perioperative IV hydrocortisone coverage back to oral maintenance:

• If patient was receiving hydrocortisone 200 mg/24 hours IV (either as continuous infusion or 50 mg every 6 hours), transition to oral prednisolone at approximately 50 mg daily initially, then taper 3
• Resume oral glucocorticoid at double the pre-surgical dose for 48 hours if recovery is uncomplicated, then return to baseline maintenance 3
• For major surgery, continue doubled oral doses for up to one week if complications arise 3

Maintenance Therapy Conversion

For patients on chronic hydrocortisone replacement being switched to prednisolone:

• Hydrocortisone 20 mg daily = Prednisolone 5 mg daily 1, 2
• Hydrocortisone 30 mg daily = Prednisolone 7.5 mg daily 1, 2
• Mean prednisolone dose for adequate adrenal replacement is approximately 3.86 mg daily (range 3-6 mg) 4, 5, 6

Acute Severe Conditions (e.g., Ulcerative Colitis)

When converting from IV hydrocortisone to oral prednisolone in acute illness:

• Hydrocortisone 100 mg IV four times daily (400 mg/day) = Methylprednisolone 60-80 mg daily = Prednisolone 60-80 mg daily 3
• Once patient tolerates oral intake and shows clinical improvement, switch directly to oral prednisolone at equivalent dosing 3

Important Clinical Considerations

Dosing Schedule Differences

• Prednisolone can be given once daily in the morning, unlike hydrocortisone which typically requires 2-3 divided doses 4, 5, 7
• Single daily dosing with prednisolone provides more convenient administration but less physiologic cortisol rhythm mimicry 5
• Splitting prednisolone doses substantially increases total glucocorticoid exposure and should be avoided unless specifically indicated 5

Bioavailability and Timing

• Prednisolone reaches peak concentration (Tmax) at approximately 1.4 hours after oral administration 5
• The pharmacokinetic profile of once-daily prednisolone is similar to dual-release hydrocortisone formulations 5
• IV to oral conversion assumes 100% bioavailability for both routes when using standard equivalency ratios 2, 8

Common Pitfalls to Avoid

Do not use higher prednisolone doses than necessary—research shows that when switching from prednisolone to modified-release hydrocortisone, the median hydrocortisone-equivalent dose decreased from 30 mg/day to 20 mg/day over 18 months, suggesting many patients on prednisolone are over-replaced 4

Monitor for cardiovascular risk factors—prednisolone is associated with significantly higher total cholesterol (6.3 vs 5.4 mmol/L) and LDL cholesterol (3.9 vs 3.2 mmol/L) compared to hydrocortisone at equivalent doses 6

Ensure adequate stress dosing protocols—patients switched to prednisolone maintenance still require stress dose adjustments during illness, with adrenal crisis rates of 5.4 per 100 patient-years reported 4

Verification of Adequacy

After conversion, assess clinical and biochemical response:

• For adrenal insufficiency: monitor for symptoms of over- or under-replacement 4, 5
• For inflammatory conditions: verify disease control parameters (e.g., 17-OHP for CAH, inflammatory markers for IBD) 4, 7
• Consider dose reduction over time—57% of patients achieved adequate control on ≤25 mg hydrocortisone-equivalent daily after 18 months, compared to only 27% at baseline 4