Half-lives of Benzos and Sleep Meds

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How long does it take for benzos and sleep meds to leave your body? With sedatives, the question matters, because you don’t want to be drowsy and discoordinated all day. The short answer is that it takes 5 half-lives (read more about half-lives and how a drug gets out of the body).

Each drug has a different half-life. Here are the figures for sleep meds:

Sleep MedHalf-life
Melatonin40-60 min
Ramelteon (Rozerem)1-2 hr
Zaleplon (Sonata)1.5 hr
Zolpidem (Ambien)2.5 hr
Prazosin2.5 hr
Diphenhydramine (Benadryl)2-4 hr
Eszopiclone (Lunesta)6 hr
Chloral hydrate8-10 hr
Doxylamine (Unisom)10 hr
Trazodone5-9 hr
Suvorexant (Belsomra)15 hr
Lemborexant (Dayvigo)18 hr
Hydroxyzine (Vistaril)20 hr
Doxepin (Silenor)15-30hr

And here are the half-lives of benzodiazepines, which are used for anxiety, agitation, and sleep

Triazolam2 hr
Oxazepam4-15 hr
Temazepam (Restoril)8-22 hr
Alprazolam (Xanax)6-12 hr
Lorazepam (Ativan)10-20 hr
Estazolam10-24 hr
Clonazepam (Klonopin)1-2 days
Quazepam1-6 days*
Diazepam (Valium)1-8 days*
Clorazepate2-8 days*
Chlordiazepoxide2-8 days*
Flurazepam2-10 days*

*Why do these benzos have such long half lives? The liver transforms them into other benzos (called active metabolites), and those other benzos take a while to leave the body.

You’ll notice some of those half-lives have quite a range – for alprazolam (Xanax) it’s 6-12 hours. Actually all of them have a range, but some vary more than others. The half-life of a drug is not static but shrinks and stretches depending on several factors, notably:

  • The older you are, the longer the half-life
  • Interactions with other drugs can change the half-life
  • Some people (about 10-20%) metabolize drugs differently, and this can be detected on a genetic test. Rapid metabolizers have shorter half-lives, while poor metabolizers have longer half-lives.

Do Benzos Treat Depression?

Around 50 controlled trials have tested benzodiazepines in depression, and the results are surprising. In this episode we look at the controversies surrounding this research and what it means for practice.

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