Corticosteroid

Dexamethasone (Decadron)

Also called Decadron

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Indications

Vasogenic cerebral edema from brain tumors, metastases or abscess
Suspected bacterial meningitis, first dose before or with antibiotics; benefit is in pneumococcal disease (off-label)
COVID-19 needing oxygen or ventilation (RECOVERY 2021) (off-label)
Airway edema: croup and post-extubation stridor (off-label)
Postoperative nausea and vomiting prophylaxis at induction (off-label)
Early moderate to severe ARDS (DEXA-ARDS 2020) (off-label)

Dosing

Where	Dose
Other common pushes	Dexamethasone: 6–10 mg IV
Antiemetics	Dexamethasone: Corticosteroid. 4–8 mg IV at induction (PONV 2025); 12 mg with an NK₁ antagonist for chemo (ASCO); hyperglycemia, perineal burning on fast push
Corticosteroid equivalence	Dexamethasone: 0.75 mg (long-acting; no mineralocorticoid effect)

On the quick cards

Mechanism of action

Dexamethasone is a fluorinated glucocorticoid that binds the glucocorticoid receptor far more avidly than cortisol and has no meaningful mineralocorticoid activity. The bound receptor switches on anti-inflammatory genes and represses NF-κB and AP-1 targets (cytokines, adhesion molecules, COX-2, VEGF); in tumor vessels this tightens the leaky blood-brain barrier, so it shrinks vasogenic but not cytotoxic edema. Gene effects outlast plasma levels, so one dose acts for 36–54 h.

Pharmacology

CNS: peritumoral edema shrinks and symptoms often improve within days; no help for cytotoxic edema after stroke or trauma
Renal: no sodium retention or potassium loss
Metabolic: hyperglycemia, even after one PONV dose, more in diabetes
Endocrine: 25–30 times the glucocorticoid potency of hydrocortisone (0.75 mg matches 20 mg) with no mineralocorticoid effect; long, strong ACTH suppression; cortisol immunoassays do not detect it
Fetal: crosses the placenta in active form because placental 11β-HSD2 inactivates it poorly, hence its use for fetal lung maturity

Pharmacokinetics

Onset	IV: plasma peak within 5 min as phosphatases free the drug; clinical effects build over hours
Duration	Biologic effect 36–54 h (SmPC; tables give 36–72 h), so once-daily dosing works
Half-life	Plasma 3.5–4.5 h (mean 4 h, Hemady label)
Distribution	Vd about 1 L/kg; crosses the blood-brain barrier and placenta
Protein binding	About 77%, mainly albumin; little CBG binding
Metabolism	Liver CYP3A4, mainly to 6β-hydroxydexamethasone; P-glycoprotein substrate
Elimination	Urine, mostly as metabolites; under 10% unchanged
Bioavailability	Oral about 80%, so oral and IV doses are interchangeable

Chemistry

9α-fluoro-16α-methylprednisolone: the 9α-fluorine raises both glucocorticoid and mineralocorticoid potency, and the 16α-methyl group cancels the mineralocorticoid effect; betamethasone is its 16β epimer
Neutral and lipophilic; the IV form is the water-soluble 21-phosphate ester, cleaved by phosphatases within minutes
US vials (4 and 10 mg/mL) state strength as dexamethasone phosphate: 4 mg equals about 3.3 mg of dexamethasone base
Some vials contain sodium sulfite and benzyl alcohol, others none; pH 7.0–8.5; protect from light

Adverse effects and cautions

In the one-pagers

Practice Pediatric Assessment and Emergencies questions free5 exam-style questions with rationales on the topic where Dexamethasone comes up most. No account or download needed.

Practice free in your browser2,150+ exam-style questions with rationales. No account, no ads. Also free on the App Store and Google Play.

Sources

FDA label: dexamethasone sodium phosphate injection, Hikma (2024)
FDA label: Hemady (2026)
UK SmPC: dexamethasone 3.3 mg/mL, AS Kalceks (2023)
RECOVERY Collaborative Group (2021)

For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.