What is the equivalent dose of prednisolone for a patient switching from dexamethasone?

Dexamethasone to Prednisolone Conversion

When converting from dexamethasone to prednisolone, use a 1:5 ratio—meaning 1 mg of dexamethasone equals 5 mg of prednisolone. 1, 2, 3

Standard Conversion Formula

• Multiply the dexamethasone dose by 5 to get the equivalent prednisolone dose 1, 2, 3
• For example:
  • Dexamethasone 4 mg = Prednisolone 20 mg 1, 4
  • Dexamethasone 6 mg = Prednisolone 30 mg 3
  • Dexamethasone 10 mg = Prednisolone 60 mg 1
  • Dexamethasone 1 mg = Prednisolone 5 mg 2, 4

Dosing Schedule Adjustments

• Switch from single daily dexamethasone dosing to divided prednisolone dosing 1
• Prednisolone should be given in 2-3 divided doses throughout the day, with the largest dose in the morning upon awakening 5
• Typical prednisolone regimens:
  • For lower doses: 4-5 mg once daily in the morning 5
  • For moderate doses: 3 mg morning + 1-2 mg at 14:00h 5
  • For higher doses: divide into three doses (e.g., 10 mg + 5 mg + 2.5 mg at 07:00,12:00, and 16:00) 5

Critical Pharmacologic Differences

• Dexamethasone has minimal mineralocorticoid activity while prednisolone has moderate mineralocorticoid effects 2, 3
• This difference matters clinically in conditions where salt and water retention are concerns 2, 3
• The 1:5 conversion ratio accounts for glucocorticoid potency but not mineralocorticoid differences 2, 3

Context-Specific Considerations

When Lower Conversion Ratios May Apply

• In prostate cancer patients on abiraterone, use a lower ratio: dexamethasone 0.5-1 mg replaces prednisolone 10 mg (approximately 1:10-20 ratio) 2, 3
• This lower ratio minimizes mineralocorticoid effects that could worsen hypertension and fluid retention in this population 2, 3

Immunosuppression Equivalence

• Patients taking prednisolone ≥20 mg daily (equivalent to dexamethasone ≥4 mg daily) have blunted vaccine responses 1, 2
• Both doses represent significant immunosuppression requiring infection monitoring 5

Common Pitfalls to Avoid

• Do not use divided dosing for dexamethasone when converting back—dexamethasone should always be given as a single daily dose 1
• Do not assume the 1:5 ratio applies universally across all clinical contexts—some conditions require adjusted ratios 2, 3
• Monitor for signs of under-replacement after conversion: fatigue, nausea, poor appetite, weight loss, increased pigmentation 5
• Monitor for signs of over-replacement: weight gain, insomnia, peripheral edema, hyperglycemia 5

Monitoring After Conversion

• Clinical assessment is the primary monitoring tool—plasma ACTH and serum cortisol are not useful for dose adjustment 5
• Assess energy levels, sleep quality, appetite, and any changes in pigmentation 5
• Ask specifically about energy "dips" during the day to optimize dose timing 5
• Consider checking blood glucose, as prednisolone may cause less hyperglycemia than dexamethasone at equivalent anti-inflammatory doses 5, 6