How long does dexamethasone stay in your system?
The amount of time it takes for dexamethasone to leave your body depends on your age, other medications you are taking, and your medical conditions. Dexamethasone is a long-acting corticosteroid. While it takes around 20 hours for it to leave the body for most people, the effects can last many days after your last dose.
What is the half-life of dexamethasone?
For most people, the average terminal half-life of dexamethasone is 4 hours. A half-life of a medication is the time it takes for the maximum drug concentration in the bloodstream to reach 50%. Based on a half-life of 4 hours, it takes about 20 hours for most dexamethasone to leave your system. This is because it takes about five half-lives for a drug to be almost completely eliminated from your body.
It can take longer for dexamethasone to leave your system if you have certain medical conditions. For example, one study found that the half-life of dexamethasone in patients in the ICU was about 9 hours. The half-life ranged from 5 hours to 19 hours in these patients, suggesting that the medication took longer to get processed and eliminated from the body.
Medications that interact with dexamethasone can cause it to get processed more slowly by your liver, which can also slow down the time it takes for it to leave your system.
Another factor that can affect how quickly dexamethasone leaves your system is age. For example, the half-life is around 9 hours in certain infants that are low birth-weight. In children 4 months to 16 years, the half-life is around 4 hours, but ranges from around 2 to 9 hours. In adults, the half-life is around 4 hours, but can range from 1 to 5 hours.
How long do the effects of dexamethasone last?
Even though dexamethasone leaves the body fairly quickly, its effects can persist for longer. The biological half-life of dexamethasone is around 36 to 54 hours. This means it loses 50% of its effectiveness after this time. The effects of dexamethasone can last for many days after you stop taking it.
References
Dexamethasone tablet [package insert]. Updated February 2024. Alvogen, Inc. Accessed on August 9, 2024 at https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9ab26af9-8196-e3d3-76a3-75227fd4e1c3
Donavon, B., et. al. Updated May 2023. Dexamethasone. In: StatPearls [Internet]. Accessed on August 10, 2024 at https://www.ncbi.nlm.nih.gov/books/NBK482130/
Li, L., et. al. 2023. Population pharmacokinetics of dexamethasone in critically ill COVID-19 patients: Does inflammation play a role? In: Journal of Critical Care. DOI: https://doi.org/10.1016/j.jcrc.2023.154395
UpToDate. Dexamethasone (systemic): Drug Information. 2024. Accessed August 10, 2024 at https://www.uptodate.com/contents/dexamethasone-systemic-drug-information
Yasir, M., et. al. Updated July 2023. Corticosteroid Adverse Effects. In: StatPearls [Internet]. Accessed on August 10, 2024 at https://www.ncbi.nlm.nih.gov/books/NBK531462/
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