Dexamethasone
Related Subjects:
|Adrenal Physiology
|Addisons Disease
|Cushing Syndrome
|Cushing Disease
๐ก About
- Always check the BNF entry (or local formulary) for the most up-to-date prescribing advice.
- Dexamethasone is a very potent systemic corticosteroid (โ25โ30 ร hydrocortisone potency) with long half-life (36โ72 h).
- Used for its strong anti-inflammatory, immunosuppressive, and anti-oedema actions.
โ๏ธ Mode of Action
- Binds to intracellular glucocorticoid receptors, alters gene transcription.
- Suppresses pro-inflammatory mediators (IL-1, TNF-ฮฑ, prostaglandins).
- Stabilises cell and lysosomal membranes โ reduces oedema (e.g. cerebral swelling).
๐ Indications & Example Doses
- Bacterial meningitis (adjunct): 8.3 mg IV every 6 h ร 4 days (start before or with first antibiotic dose).
- Cerebral oedema: 8โ16 mg IV/IM stat, then 5 mg IV/PO every 6 h, taper when improved.
- Cerebral oedema (malignancy): 0.5โ10 mg PO daily (adjust to symptoms).
- Inflammatory / allergic disorders: 0.5โ10 mg PO daily.
- Cushingโs diagnosis (overnight suppression test): 1 mg PO at 23:00 โ check 09:00 cortisol.
- Palliative care:
- Anorexia: 2โ4 mg PO daily.
- Nausea, headache, raised ICP: 8โ16 mg PO daily.
- COVID-19 (hospitalised with hypoxia): 6 mg PO/IV once daily up to 10 days (RECOVERY trial).
โ ๏ธ Always titrate to indication, duration, and patient response. Long courses require tapering to avoid adrenal crisis.
๐ Steroid Equivalence (approximate)
| Drug | Equivalent Anti-inflammatory Dose | Relative Potency | Mineralocorticoid Activity |
|---|
| Hydrocortisone | 20 mg | 1 | High |
| Prednisolone | 5 mg | 4 | Low |
| Dexamethasone | 0.75 mg | โ25โ30 | None |
๐ Interactions
- See BNF - key interactions: NSAIDs (โ GI bleed risk), CYP3A4 inducers/inhibitors, hypoglycaemic agents, vaccines (reduced efficacy).
โ ๏ธ Cautions
- Congestive cardiac failure, hypertension, diabetes, untreated infection.
- Peptic ulcer disease.
- Psychiatric illness โ risk of steroid-induced psychosis.
- May mask signs of sepsis.
๐ซ Contraindications
- Untreated systemic infection (unless on appropriate antimicrobials).
๐ฅ Side Effects
- Short-term: insomnia, euphoria, mood change, hyperglycaemia, raised WCC (neutrophilia).
- Long-term: Cushingoid appearance, adrenal suppression, osteoporosis, myopathy, cataracts/glaucoma, diabetes, immunosuppression.
- Serious: avascular necrosis of femoral head, acute psychosis.
๐ References
๐ Revisions
- Expanded with equivalence and COVID-19 indication โ August 2025
