What is the equivalent dose of hydrocortisone for an adult patient with no significant kidney or liver dysfunction converting from prednisone?

Prednisone to Hydrocortisone Conversion

For an adult patient with normal kidney and liver function, 5 mg of prednisone is equivalent to 20 mg of hydrocortisone, using the standard 4:1 conversion ratio. 1, 2, 3, 4

Standard Conversion Ratio

• The established conversion is 4:1 (hydrocortisone:prednisone), meaning prednisone is 4 times more potent than hydrocortisone on a milligram-per-milligram basis. 1, 2, 3

• This ratio is consistently validated across multiple authoritative sources including perioperative guidelines, endocrinology consensus statements, and FDA labeling. 1, 4

Common Dose Equivalents

Using the 4:1 ratio, the following conversions apply:

• Prednisone 5 mg = Hydrocortisone 20 mg 1, 2, 3, 4
• Prednisone 10 mg = Hydrocortisone 40 mg 1, 2
• Prednisone 50 mg = Hydrocortisone 200 mg 2, 3
• Prednisone 60 mg = Hydrocortisone 240 mg 3

Clinical Context for Conversion

When converting from prednisone to hydrocortisone for physiologic replacement therapy (such as in adrenal insufficiency), typical maintenance dosing is hydrocortisone 15-25 mg daily in divided doses (usually 10 mg + 5 mg + 2.5-5 mg), which would be equivalent to approximately prednisone 4-6 mg daily. 1

For stress-dose coverage (such as perioperative or acute illness), hydrocortisone 200 mg/24 hours IV is equivalent to approximately prednisone 50 mg daily. 1, 2, 3

Important Pharmacologic Differences

Beyond simple dose equivalence, there are critical differences between these two agents:

• Mineralocorticoid activity: Hydrocortisone has significant mineralocorticoid activity, while prednisone has approximately 25 times less mineralocorticoid effect. 3 This means patients with primary adrenal insufficiency converting from hydrocortisone to prednisone will require separate fludrocortisone supplementation (typically 50-200 mcg daily). 1

• Dosing frequency: Hydrocortisone has a plasma half-life of approximately 90 minutes and requires multiple daily doses (typically 2-3 times daily), whereas prednisone has a longer duration of action allowing once or twice daily dosing. 1

• Bioavailability: Both agents have excellent oral bioavailability, though prednisone requires hepatic conversion to prednisolone (the active form) for biological activity. 5

Critical Caveat for Liver Disease

In patients with active liver disease (elevated bilirubin and transaminases), the conversion of prednisone to its active form prednisolone is impaired, resulting in lower biologically active steroid levels than expected. 5 In such patients, either use prednisolone directly or use hydrocortisone, which does not require hepatic activation. 5

Practical Application Algorithm

When converting between these agents, follow this approach:

1. Calculate the equivalent dose using the 4:1 ratio (hydrocortisone:prednisone)
2. Assess for primary vs. secondary adrenal insufficiency: If primary, add fludrocortisone when using prednisone 1
3. Adjust dosing schedule: Hydrocortisone requires 2-3 daily doses; prednisone can be given once daily 1
4. Monitor clinical response: Watch for signs of under-replacement (fatigue, nausea, weight loss, increased pigmentation) or over-replacement (weight gain, insomnia, edema) 1
5. Check liver function: If hepatic impairment exists, consider using hydrocortisone or prednisolone instead of prednisone 5