Prednisone to Dexamethasone Conversion
The equivalent dose of dexamethasone for prednisone 20 mg is 4 mg, as dexamethasone is approximately 5 times more potent than prednisone. 1
Corticosteroid Potency Ratios
- Dexamethasone is 25 times more potent than hydrocortisone (cortisol) 1
- Prednisone is 4 times more potent than hydrocortisone 1
- Methylprednisolone is 5 times more potent than hydrocortisone 1
- Based on these ratios, dexamethasone is approximately 6.25 times more potent than prednisone (25 ÷ 4), but in clinical practice, a 5:1 ratio (prednisone:dexamethasone) is commonly used 1
Conversion Table for Common Corticosteroids
- Prednisone 5 mg = Dexamethasone 1 mg 1
- Prednisone 20 mg = Dexamethasone 4 mg 1
- Prednisone 60 mg = Dexamethasone 10 mg 1
- Prednisone 60 mg = Methylprednisolone 48 mg 1
Clinical Considerations
- Single daily dosing is recommended for dexamethasone rather than divided doses 2
- Dexamethasone has a longer half-life (36-54 hours) compared to prednisone (12-36 hours), which may affect dosing frequency 3, 4
- When switching between corticosteroids, consider the clinical context and indication for therapy 1
- For perioperative use in patients with inflammatory bowel disease, hydrocortisone 20 mg IV is equivalent to oral prednisolone 5 mg 1
Special Situations
- For acute asthma exacerbations, a single dose of oral dexamethasone (12 mg) has been shown to be nearly as effective as a 5-day course of prednisone (60 mg daily) 3
- In pediatric asthma, a single dose of dexamethasone (0.3 mg/kg) was found to be non-inferior to a 3-day course of prednisolone (1 mg/kg/day) 5
- For immune thrombocytopenia, pulsed dexamethasone (0.6 mg/kg/day for 4 days) may provide longer remissions than daily prednisone 6
Important Considerations When Switching Corticosteroids
- Patients taking prednisone ≥20 mg daily (or equivalent) may have a blunted response to certain vaccinations 1
- For non-emergency surgery, corticosteroids should be minimized when possible to reduce postoperative complications 1
- When using high-dose corticosteroids, be aware of potential adverse effects including hyperglycemia, sleep disturbances, and increased infection risk 1
Remember that while these conversion ratios provide a useful guideline, individual patient factors such as comorbidities, concomitant medications, and specific indications may necessitate dose adjustments.