Hydrocortisone
💡 Patients on long-term steroids need an increased dose when acutely unwell (“steroid sick day rules”).
Failure to escalate can precipitate an adrenal crisis.
📘 About
- Always check the BNF entry for up-to-date prescribing advice.
- Hydrocortisone is a corticosteroid with both glucocorticoid and mineralocorticoid activity.
- Used in replacement therapy (Addison’s, hypopituitarism) and in acute inflammatory/allergic reactions.
⚙️ Mode of Action
- Binds to intracellular glucocorticoid receptors → modifies gene transcription → suppresses inflammation & immune response.
- Also binds to mineralocorticoid receptors → increases renal sodium reabsorption and potassium excretion.
- Short half-life (8–12 h) → requires multiple daily dosing for replacement therapy.
💊 Indications & Example Doses
- Adrenal crisis / acute severe illness: Hydrocortisone 100 mg IV stat, then 50–100 mg IV/IM every 6 h, with IV fluids.
- Chronic replacement (Addison’s / hypopituitarism): Hydrocortisone 15–30 mg PO daily, in 2–3 divided doses (largest in the morning to mimic circadian rhythm).
- Severe allergic or inflammatory reactions: 100–200 mg IV every 6–8 h.
- Stress dosing (“sick day rules”): Double usual oral dose during intercurrent illness; use IV if unable to take orally.
📊 Steroid Equivalence
| Drug | Equivalent Dose | Relative Potency | Mineralocorticoid Effect |
|---|
| Hydrocortisone | 20 mg | 1 | High |
| Prednisolone | 5 mg | ≈4 | Low |
| Dexamethasone | 0.75 mg | ≈25–30 | None |
🔀 Interactions
- See BNF for full list.
- NSAIDs → ↑ GI bleed risk.
- CYP3A4 inducers (e.g. rifampicin, carbamazepine) → ↓ steroid effect.
- CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) → ↑ steroid exposure.
⚠️ Cautions
- Hypertension, diabetes mellitus, peptic ulcer disease, osteoporosis.
- Active or latent infection (e.g. TB) - may be masked/worsened.
- Psychiatric illness - may precipitate acute psychosis.
- Adrenal suppression if stopped suddenly after prolonged use → taper slowly.
🚫 Contraindications
- Untreated systemic infection (unless on appropriate antimicrobials).
- Hypersensitivity to hydrocortisone or excipients.
💥 Side Effects
- Short-term: mood change, insomnia, hyperglycaemia, increased WCC.
- Long-term: Cushingoid features, osteoporosis, muscle weakness, diabetes, cataracts/glaucoma, immunosuppression.
- Serious: adrenal crisis if omitted in dependent patients.
📚 References
