Switching from Hydrocortisone to Prednisone
Use a 4:1 conversion ratio (20 mg hydrocortisone = 5 mg prednisone) and switch directly without tapering the hydrocortisone first, giving the prednisone as a single morning dose. 1, 2
Dose Conversion
- Convert using the established equivalency: 20 mg hydrocortisone equals 5 mg prednisone 1, 2
- Calculate total daily hydrocortisone dose and divide by 4 to get the prednisone equivalent 1
- For example: A patient on hydrocortisone 30 mg/day would switch to prednisone 7.5 mg/day 1
Important nuance: While this 4:1 ratio is the standard conversion, recent pharmacokinetic data suggests prednisolone may be slightly less potent than methylprednisolone or dexamethasone for certain endpoints like adrenal suppression, though the clinical significance is minimal at therapeutic doses 3. The 4:1 ratio remains the accepted standard for clinical practice 1, 2.
Timing and Administration
- Give prednisone as a single morning dose rather than divided dosing to minimize HPA axis suppression 4
- Make the switch abruptly—there is no need to overlap or taper the hydrocortisone first 1
- Administer prednisone between 6-8 AM to mimic physiologic cortisol rhythm 4
The single daily dosing is preferred except in rare situations like prominent night pain while on low doses (<5 mg daily), where divided dosing may be considered 5, 4.
Clinical Context for Switching
Prednisone offers several advantages over hydrocortisone:
- Longer half-life allows once-daily dosing, improving adherence 6
- Better mental health and quality of life outcomes in recent prospective data comparing prednisone to hydrocortisone in patients recovering from hypercortisolism 7
- More convenient for patients requiring long-term glucocorticoid replacement 6
However, hydrocortisone is preferred for acute stress dosing because it provides mineralocorticoid activity at physiologic doses, which prednisone lacks 1, 8.
Monitoring After Conversion
- Check disease-specific markers at 2-4 weeks after conversion to ensure adequate control 4
- For adrenal insufficiency patients, assess for symptoms of under-replacement (fatigue, hypotension, nausea) or over-replacement (weight gain, hyperglycemia, hypertension) 1
- Monitor for signs of HPA axis suppression if the patient is on chronic therapy, as prednisone may suppress the axis differently than hydrocortisone 9
Critical Pitfalls to Avoid
Do not use hydrocortisone's divided dosing schedule for prednisone. If a patient was on hydrocortisone 10 mg/5 mg/5 mg (morning/afternoon/evening), convert the total 20 mg to prednisone 5 mg given once in the morning only 4, 1.
Educate patients on stress dosing requirements. During acute illness or physiologic stress, patients need supplemental glucocorticoids 1, 8:
- For minor illness: double the current prednisone dose for 3 days 1
- For major stress (surgery, severe illness): switch temporarily to hydrocortisone 50-100 mg IV, as prednisone lacks mineralocorticoid activity needed during crisis 1, 8
Ensure patients have emergency hydrocortisone injection kit (100 mg) and medical alert identification, as prednisone-treated patients remain at risk for adrenal crisis during severe stress 1, 8.
Special Consideration: HPA Axis Recovery
Recent data suggests that patients maintained on once-daily prednisone may have better HPA axis recovery rates (70%) compared to those converted to multiple-dose hydrocortisone (15%) when weaning off chronic glucocorticoid therapy 9. This finding challenges the traditional practice of converting to hydrocortisone for weaning, though the study was retrospective and requires confirmation 9.