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Potent Systemic Corticosteroid Pregnancy: Crosses placenta (not metabolised by placenta unlike prednisolone) — used deliberately for fetal lung maturation at 24–34 weeks. Systemic use in mother: minimise exposure; use prednisolone instead where possible.

Dexamethasone

Brand names: Dexsol, Martapan, Neofordex

Adult dose

Dose: Cerebral oedema: 10mg IV/IM stat, then 4mg IV/IM every 6h. Croup (adults/older children): 0.15–0.6mg/kg oral/IM single dose (max 10mg). Chemotherapy anti-emesis: 8–20mg IV/oral before chemotherapy. COVID-19 (RECOVERY trial): 6mg OD for 10 days. Bacterial meningitis: 0.15mg/kg IV QDS for 4 days (given before or with first antibiotic dose). Adrenal insufficiency crisis: not first-line (use hydrocortisone). Dexamethasone suppression test: 1mg oral at 11pm.
Route: Oral / IM / IV
Frequency: Varies by indication — see doses
Max: Indication-specific; cerebral oedema: 24mg/day initially
No mineralocorticoid activity — does not cause sodium retention. Biological half-life 36–54h. Dexamethasone 0.75mg ≡ prednisolone 5mg ≡ hydrocortisone 20mg. Crosses blood-brain barrier effectively. Crosses placenta (not inactivated like prednisolone) — used for fetal lung maturation.

Paediatric dose

Dose: 0.15 mg/kg
Route: Oral / IM / IV
Frequency: Single dose for croup; varies for other indications
Max: 10mg single dose (croup)
BNFc: Croup: 0.15mg/kg single dose oral/IM (max 10mg) — preferred over prednisolone for croup due to longer duration. Cerebral oedema: 0.25mg/kg every 6h. Bacterial meningitis: 0.15mg/kg QDS for 4 days. Seek specialist paediatric opinion for complex indications.

Dose adjustments

Renal

No dose adjustment required. Monitor fluid and electrolytes — though mineralocorticoid effect minimal.

Hepatic

Use with caution in severe hepatic impairment — monitor for enhanced glucocorticoid effects.

Paediatric weight-based calculator

BNFc: Croup: 0.15mg/kg single dose oral/IM (max 10mg) — preferred over prednisolone for croup due to longer duration. Cerebral oedema: 0.25mg/kg every 6h. Bacterial meningitis: 0.15mg/kg QDS for 4 days. Seek specialist paediatric opinion for complex indications.

Clinical pearls

  • RECOVERY trial: dexamethasone 6mg OD reduced 28-day mortality by 35% in ventilated COVID-19 patients — landmark finding
  • Dexamethasone suppression test: failure to suppress morning cortisol to <50 nmol/L after 1mg at 11pm suggests Cushing's syndrome — screen test (not diagnostic alone)
  • Bacterial meningitis: give dexamethasone 10 minutes BEFORE or with first dose of antibiotics to reduce inflammatory cascade — reduces hearing loss in pneumococcal meningitis (NICE)
  • Fetal lung maturation: betamethasone 12mg IM × 2 doses (24h apart) preferred over dexamethasone for this indication — more evidence base

Contraindications

  • Systemic infection without antimicrobial cover (relative)
  • Live vaccines
  • Hypersensitivity to dexamethasone

Side effects

  • Hyperglycaemia
  • Insomnia (commonly — take in morning)
  • Mood disturbance/psychosis
  • Adrenal suppression
  • Osteoporosis (long-term)
  • Proximal myopathy
  • Cushing's syndrome (long-term)
  • Immunosuppression

Interactions

  • Rifampicin — markedly reduces dexamethasone efficacy (CYP3A4 induction) — dose increase required
  • Phenytoin, carbamazepine — reduce dexamethasone efficacy
  • Antidiabetic drugs — dose adjustment required for hyperglycaemia
  • Live vaccines — contraindicated at immunosuppressive doses

Monitoring

  • Blood glucose (daily in hospital setting)
  • Blood pressure
  • Mood and sleep disturbance
  • Intraocular pressure (long-term)
  • Bone density (DEXA) if prolonged use

Reference: BNFc; BNF 90; RECOVERY Trial (NEJM 2021); NICE Bacterial Meningitis Guideline; NICE NG187. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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