Steroid Equivalence: Corticosteroid Dose Conversion & Clinical Guide

Corticosteroids are among the most widely prescribed drugs in medicine. They are used in conditions as diverse as severe asthma, rheumatoid arthritis, nephrotic syndrome, meningitis, COVID-19, organ transplantation, adrenal insufficiency, and anaphylaxis. Yet few drug classes are as frequently misused, poorly converted between agents, or inappropriately stopped.

The most common error is assuming that all corticosteroids are interchangeable at the same dose — they are not. Prednisolone 5 mg is equivalent to dexamethasone 0.75 mg, which is equivalent to hydrocortisone 20 mg. Giving a patient 5 mg of dexamethasone when you intended 5 mg of prednisolone is a 6–7× overdose. Understanding steroid equivalence is therefore a basic patient safety issue.

The Reference Steroid — Hydrocortisone

All corticosteroid potencies are expressed relative to hydrocortisone (cortisol) — the body's own naturally produced glucocorticoid. The adrenal cortex produces approximately 20 mg of hydrocortisone per day under basal conditions, rising to 100–300 mg/day during physiological stress (surgery, sepsis). This is important for understanding steroid replacement therapy and stress dosing.

Hydrocortisone has a reference anti-inflammatory potency of 1× and significant mineralocorticoid activity (causes sodium retention and potassium loss). All other corticosteroids are compared to this baseline.

Corticosteroid Equivalence Reference Table

Key Clinical Notes on Individual Steroids

Prednisolone vs Prednisone

Prednisone is a prodrug that must be converted to prednisolone in the liver. For most patients they are clinically interchangeable. However, prednisolone is strongly preferred in severe hepatic impairment — a cirrhotic liver may not adequately convert prednisone to its active form. Always prescribe prednisolone (not prednisone) for patients with significant liver disease.

Dexamethasone — No Mineralocorticoid Activity

Dexamethasone has zero mineralocorticoid activity — it does not cause sodium or water retention. This makes it the preferred agent when oedema is a concern, or when high-dose steroids are needed in patients with hypertension, heart failure, or fluid-sensitive states. Specific indications where dexamethasone is preferred:

• Brain oedema: Dexamethasone 4–8 mg every 6 hours — standard for vasogenic oedema from tumour, abscess, or surgery
• Antenatal lung maturation: Two doses of betamethasone (similar potency) at 24h intervals — reduces RDS risk in preterm labour
• COVID-19 (RECOVERY trial): Dexamethasone 6 mg once daily for 10 days reduced 28-day mortality in ventilated patients by 36%
• Bacterial meningitis: Dexamethasone 0.15 mg/kg every 6 hours for 4 days — reduces hearing loss and neurological complications
• Anti-emesis: Single dose dexamethasone 4–8 mg IV is one of the most effective antiemetics available
• Croup: Single oral or IM dose 0.15–0.6 mg/kg — standard treatment for moderate-severe croup

Hydrocortisone — Strong Mineralocorticoid Activity

Hydrocortisone is the preferred steroid for physiological replacement in adrenal insufficiency (Addison's disease). The physiological replacement dose is 15–25 mg/day in divided doses (commonly 10 mg morning + 5 mg afternoon, or 10+5+5). In adrenal crisis, give hydrocortisone 100 mg IV stat then 50–100 mg every 6–8 hours or as a continuous infusion of 200 mg over 24 hours.

In septic shock with refractory vasopressor dependence, hydrocortisone 200 mg/day (by infusion or 50 mg every 6h) is recommended — it provides both glucocorticoid AND mineralocorticoid cover, reducing vasopressor requirements.

Methylprednisolone — High Potency, No Mineralocorticoid

Methylprednisolone is the preferred IV steroid for acute severe asthma and COPD exacerbations (40–80 mg IV), acute transplant rejection (500–1000 mg IV "pulse"), acute spinal cord injury (controversial — no longer recommended by most guidelines), and acute severe inflammatory conditions requiring rapid IV therapy.

Use Cases by Condition

HPA Axis Suppression — When and How to Taper

The hypothalamic-pituitary-adrenal (HPA) axis regulates the body's own cortisol production. When exogenous corticosteroids are given, the HPA axis is suppressed — the adrenal gland stops producing its own cortisol. If steroids are then abruptly stopped, the adrenal gland cannot immediately resume function, causing adrenal insufficiency — potentially life-threatening.

The risk of HPA suppression depends on:

• Dose: Prednisolone > 7.5 mg/day (equivalent) for > 3 weeks causes significant suppression
• Duration: Short courses (< 3 weeks) at any dose rarely cause clinically significant suppression
• Timing: Steroids given at night suppress the morning cortisol surge more than morning dosing
• Route: Inhaled and topical steroids can cause suppression at high doses but far less than systemic

Steroid Tapering — General Principles

• Short courses (< 3 weeks): Can usually stop abruptly — no taper needed
• 3 weeks to 3 months: Reduce by 10–20% of current dose every 1–2 weeks while monitoring for relapse symptoms
• > 3 months or > 40 mg prednisolone equivalent: Slow taper over months. Below 10 mg/day (prednisolone), reduce by 1 mg per month — the adrenal axis is most vulnerable at this range
• Always reduce more slowly at the physiological replacement level (prednisolone 5–7.5 mg = approximately physiological cortisol production)
• Counsel patients to carry a steroid card and seek urgent medical help if they are unwell — sick-day rules require doubling the steroid dose during febrile illness or surgery

Side Effects of Long-Term Corticosteroids

The side effect profile of systemic corticosteroids is extensive. Clinicians must monitor proactively:

This article is for educational purposes based on standard pharmacological references. Corticosteroid prescribing, dose conversion, and tapering decisions must be made by a qualified physician. Never change steroid doses without medical supervision.

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