Systemic corticosteroids · Endocrine
Dexamethasone
Decadron®(brand names vary by market)
High potency, long duration, and almost no mineralocorticoid effect.
Also: oral liquid, injection
Mechanism
A potent, long-acting glucocorticoid with negligible mineralocorticoid activity: strong anti-inflammatory effect without the sodium retention.
Indications
- Cerebral oedema and raised intracranial pressure
- Chemotherapy-induced nausea
- Croup
- Severe COVID-19 requiring oxygen
- Antenatal fetal lung maturation
- Adrenal suppression testing
Formulations
Dosing concepts
Single doses
Its long duration means one dose can do a day's work, which is why it dominates the antiemetic and croup roles.
Not for adrenal replacement
Almost no mineralocorticoid activity, so it cannot replace the aldosterone arm; hydrocortisone with fludrocortisone does that job.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Bioavailability
- ~80%
- Half-life
- Plasma 3 to 5 h; biological effect 36 to 72 h
- Elimination
- hepatic: CYP3A4 substrate and inducer
- Protein binding
- ~70%
Adverse effects
- Hyperglycemiacommon & serious
- Insomnia and agitationcommon
- Infection riskserious
- Proximal myopathy with prolonged useseriousCharacteristic of the fluorinated steroids and easily mistaken for disease progression.
- Perineal burning with rapid intravenous injectioncommonAlarming, harmless, and preventable by injecting slowly.
Contraindications & precautions
Contraindications
- Systemic fungal infection
- Live vaccines at immunosuppressive doses
Precautions
- Diabetes
- Psychiatric history
- Concurrent CYP3A4 interactions
- Prolonged courses
Interactions
No curated interaction entries yet for this agent.
Monitoring
Glucose
The most predictable acute effect
Mood and sleep
Common at these potencies
Proximal strength on long courses
Steroid myopathy is reversible if recognised
Counselling points
- Take it in the morning with food.
- Your blood sugar may rise; if you are diabetic, test more often for a few days.
- You may feel wide awake or unusually energetic for a day or two.
- Tell us if you have been on it more than a couple of weeks before stopping.
Clinical pearls
- Roughly six to seven times prednisone's glucocorticoid potency and much longer acting: the conversion is worth knowing because patients move between them on transfer between services.
- In cerebral oedema from tumour it works within hours and is one of the more dramatic interventions in medicine; in traumatic brain injury it is harmful. Same oedema, opposite answer.
References & review
- Dexamethasone product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-16 · jurisdiction: global · drug information changes; verify against current references before practice use.