What Are Corticosteroids?
Corticosteroids (often simply called "steroids" in a medical context, not to be confused with anabolic steroids) are a class of steroid hormones produced naturally by the adrenal cortex. Synthetic corticosteroids are among the most widely prescribed medications in the world, used for their potent anti-inflammatory and immunosuppressive properties.
These medications are used to treat a vast array of conditions, including asthma, allergic reactions, autoimmune diseases (rheumatoid arthritis, lupus, inflammatory bowel disease), organ transplant rejection, and many others. They work primarily by suppressing the immune system and reducing inflammation at the cellular level.
Corticosteroids have two main types of activity: glucocorticoid (GC) activity, which is responsible for anti-inflammatory and immunosuppressive effects, and mineralocorticoid (MC) activity, which affects sodium and water retention. Different synthetic steroids have varying ratios of these activities.
Steroid Equivalency Table
The following table shows the approximate equivalent anti-inflammatory doses of commonly used corticosteroids, along with their relative glucocorticoid and mineralocorticoid potencies:
| Corticosteroid | Equivalent Dose (mg) | GC Potency | MC Potency | Biological Half-Life | Duration |
|---|---|---|---|---|---|
| Hydrocortisone (Cortisol) | 20 | 1 | 1 | 8–12 h | Short |
| Cortisone | 25 | 0.8 | 0.8 | 8–12 h | Short |
| Prednisone | 5 | 4 | 0.8 | 12–36 h | Intermediate |
| Prednisolone | 5 | 4 | 0.8 | 12–36 h | Intermediate |
| Methylprednisolone | 4 | 5 | 0.5 | 12–36 h | Intermediate |
| Triamcinolone | 4 | 5 | 0 | 12–36 h | Intermediate |
| Dexamethasone | 0.75 | 25 | 0 | 36–54 h | Long |
| Betamethasone | 0.6 | 25–30 | 0 | 36–54 h | Long |
Conversion Formula
The conversion between corticosteroids uses their equivalent doses relative to hydrocortisone 20 mg as a reference:
For example, to convert Prednisone 20 mg to Dexamethasone:
This formula works because the equivalent doses represent the amount of each steroid that produces the same anti-inflammatory effect as hydrocortisone 20 mg. The ratio of equivalent doses gives you the conversion factor between any two steroids.
Corticosteroid Pharmacology
Mechanism of Action
Corticosteroids exert their effects by binding to intracellular glucocorticoid receptors. The steroid-receptor complex then translocates to the cell nucleus where it modulates gene transcription. This leads to:
- Transactivation: Increased production of anti-inflammatory proteins (lipocortin-1, IL-10, IkB)
- Transrepression: Decreased production of pro-inflammatory mediators (cytokines, chemokines, prostaglandins, leukotrienes)
- Non-genomic effects: Rapid effects on cell membranes and signaling pathways (particularly at high doses)
Glucocorticoid vs. Mineralocorticoid Activity
Glucocorticoid (GC) activity produces anti-inflammatory, immunosuppressive, and metabolic effects. Mineralocorticoid (MC) activity promotes sodium retention and potassium excretion by the kidneys, leading to fluid retention and potential hypertension.
Short-acting steroids (hydrocortisone, cortisone) have significant mineralocorticoid activity. Intermediate-acting steroids (prednisone, methylprednisolone) have moderate MC activity. Long-acting steroids (dexamethasone, betamethasone) have essentially no MC activity, making them preferred when fluid retention must be avoided.
Adrenal Suppression
One of the most important considerations in corticosteroid therapy is the suppression of the hypothalamic-pituitary-adrenal (HPA) axis. When exogenous steroids are administered, the body reduces its own cortisol production. This suppression can occur with:
- Any dose of systemic corticosteroid given for more than 3 weeks
- Prednisone ≥7.5 mg/day (or equivalent) for more than 3 weeks
- Evening doses (which more effectively suppress the morning ACTH surge)
- Repeated short courses within a year
After prolonged use, abrupt discontinuation can lead to adrenal crisis — a potentially life-threatening condition characterized by hypotension, hypoglycemia, severe fatigue, and cardiovascular collapse. This is why gradual tapering is essential.
Tapering Protocols
There is no universally agreed-upon tapering protocol, but general principles include:
- Duration < 1 week: Generally safe to stop abruptly (for most patients)
- Duration 1–3 weeks: Rapid taper over 1–2 weeks is usually sufficient
- Duration > 3 weeks: Gradual taper required. Common approach: reduce by 10–20% every 1–2 weeks
- Prolonged high-dose therapy: May require months of gradual tapering with monitoring of cortisol levels
A common tapering approach for prednisone is to reduce by 5 mg/week until reaching 20 mg/day, then reduce by 2.5 mg/week until reaching 10 mg/day, then reduce by 1 mg every 1–2 weeks. The final stages of tapering are the most critical because the HPA axis recovery occurs at physiological replacement doses (approximately prednisone 5–7.5 mg/day or hydrocortisone 20 mg/day).
Side Effects
Corticosteroid side effects are dose- and duration-dependent:
| System | Side Effects |
|---|---|
| Metabolic | Hyperglycemia, diabetes, weight gain, Cushingoid features, dyslipidemia |
| Musculoskeletal | Osteoporosis, avascular necrosis, myopathy, growth suppression (children) |
| Gastrointestinal | Peptic ulcers (especially with NSAIDs), pancreatitis |
| Cardiovascular | Hypertension, fluid retention, accelerated atherosclerosis |
| Dermatologic | Thin skin, easy bruising, impaired wound healing, striae, acne |
| Ophthalmologic | Cataracts, glaucoma |
| Neuropsychiatric | Insomnia, mood changes, psychosis (high doses), cognitive impairment |
| Immune | Increased infection risk, reactivation of latent TB, impaired vaccine response |
| Endocrine | HPA axis suppression, adrenal insufficiency on withdrawal |
Worked Example
A patient on Prednisone 40 mg daily needs to be switched to Dexamethasone:
The equivalent Hydrocortisone dose would be: 40 × (20 / 5) = 160 mg
Note that while the anti-inflammatory potency is equivalent, dexamethasone has a much longer duration of action (36–54 hours vs. 12–36 hours) and zero mineralocorticoid activity, so clinical adjustments may be needed.
Frequently Asked Questions
Are the conversions exact?
No. Steroid equivalency tables provide approximate conversions for anti-inflammatory (glucocorticoid) potency. Individual patient responses vary based on the condition being treated, route of administration, drug metabolism, and protein binding. These conversions should serve as starting points, with clinical monitoring and dose adjustment as needed.
Can I use this for inhaled or topical steroids?
No. This calculator is designed for systemic (oral/IV) corticosteroid conversion only. Inhaled and topical corticosteroids have their own potency classifications that are not directly comparable to systemic equivalencies due to differences in bioavailability and local vs. systemic effects.
What is the difference between prednisone and prednisolone?
Prednisone is a prodrug that must be converted to prednisolone (its active form) by the liver. In patients with normal liver function, they are essentially interchangeable at the same dose. However, in patients with severe liver disease, prednisolone may be preferred because it does not require hepatic activation.
Why is dexamethasone preferred for certain conditions?
Dexamethasone is preferred when long duration of action is desired, when minimal mineralocorticoid effect is needed (e.g., cerebral edema, where fluid retention is harmful), or when suppression of ACTH is the goal (e.g., diagnostic testing). Its high potency also means smaller tablets and lower fluid volumes for injection.
What is a physiological replacement dose?
The adrenal glands normally produce approximately 5–7.5 mg of prednisone equivalent per day (or 15–25 mg hydrocortisone). Doses at or below this level are considered "replacement" doses. Doses above this are considered "pharmacological" or "supraphysiological" and are more likely to cause side effects with prolonged use.