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Ativan Half-Life, Peak Concentration & Duration

half life of ativan

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Table of Contents

How Long Does Ativan Effects Last?

Ativan typically lasts for 6-8 hours and is out of the system after 72 hours. The drug’s effects can be felt within 2 hours after administration. The drug’s half-life is between 12 and 18 hours. When taken orally, the drug is absorbed into the gastrointestinal tract.

Ativan Half-Life

Ativan (generically, Lorazepam) is a benzodiazepine that’s used to treat generalized anxiety, insomnia, nausea, and seizures. It’s also used in medical facilities to sedate aggressive patients. And, like all drugs, it can be used recreationally.

Recreational use of Ativan is considered abuse and is illegal. Note that Ativan is habit-forming and even if administered as prescribed, patients can develop a tolerance and dependency.

Ativan has an intermediate half-life which, according to clinical research, is longer than that of Xanax but shorter than that of Valium. The average half-life of Ativan is around 12 hours, but some studies suggest it could be up 18 hours.
Note that the primary metabolite of Lorazepam, Lorazepam Glucuronide, has a longer half-life of up to 18 hours.

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Ativan Peak Plasma Concentration

The peak concentration of Ativan is reached up to 2 hours after intake. Ativan is absorbed directly into the gastrointestinal tract when it is taken orally but it can be administered intravenously as well.

Ativan Effects Duration

Users can feel the initial effects of the drug up to 2 hours after administration, as stated above. Its effects will typically last for 6 to 8 hours. Most doctors will prescribe 2 to 3 doses a day.

Note that when Ativan is taken intravenously, the drug has a longer duration period.

Although there’s minimal risk of excessive accumulation in the system, Ativan shouldn’t be taken for periods longer than prescribed because it can be habit-forming with harmful, even life-threatening, withdrawal symptoms.

How Long Does Ativan Stay In The System?

Research shows that Ativan is typically out of the system after 72 hours.
Various factors influence how long Ativan can stay in the system:

  • Individual physical factors (age, weight, height, genetics, general health)
  • Dosage (the body metabolizes higher doses at a slower pace)
  • History of abuse
  • Other drugs (data shows that alcohol, for example, reduces the clearance rate by 18%)

Before beginning an Ativan prescription it’s important to learn more about its side effects and abuse potential. It is not advisable to stop the drug abruptly because it could potentially lead to fatal withdrawal symptoms. Always consult a doctor for the proper dosage, course of administration and other available treatment options.

  1. Greenblatt D. J. Clinical pharmacokinetics of oxazepam and lorazepam. Clinical Pharmacokinetics. 1981; 6(2):89-105.
  2. The U.S. Department of Health & Human Services. Lorazepam – Medical Countermeasures Database. 2019.
  3. The U.S. Food and Drug Administration. Ativan® CIV (lorazepam) Tablets Rx only. 2007.
Sharon Levy

About Author

Sharon Levy, MD, MPH

After successful graduation from Boston University, MA, Sharon gained a Master’s degree in Public Health. Since then, Sharon devoted herself entirely to the medical niche. Sharon Levy is also a certified addiction recovery coach.


Leave a comment

  • Sol
    I’ve heard that irritability can set in as the Ativan wears off that is significant. I’ve also heard Ativan use correlates to having automobile accidents more frequently due to Ativan’s blocking normal (healthy) inhibitions. Is any of this true?
  • Beverly
    Is a low dose also hurtfully to you. I take for anxiety and depression. 05 mg. twice a day. Every six hours.
  • Jean
    Sol and Beverly, I am a long-term, low dose user of Ativan, and never noticed irritability as the dose wears off and have not noticed the medicine to affect driving. Also, at the low levels at which you are taking it Beverly, I haven’t noticed any harmful effects. The only concern I have is that to stop the medicine you have to very gradually decrease the amount over weeks and sometimes months. Of course, it is habit-forming, but definitely helps with symptoms so is worth it for me.