Dexamethasone (Decadron) Injection Duration
A Decadron (dexamethasone) injection has a biologic half-life of about 36–54 hours, meaning the medication’s physiologic effects can persist for several days. [1]
Plasma vs Biologic Persistence
The plasma half-life is much shorter (about 3.5–4.5 hours), so measurable drug levels decline faster than clinical effects. [2]
Practical Timeframe After a Single Injection
Clinical effects commonly persist for ~2–3 days after a single dose, consistent with a biologic half-life in the 36–54 hour range. [1]