Lorazepam Half Life: How Long Does Ativan Last?

when to take lorazepam for anxiety

Lorazepam is a benzodiazepine medication used to treat anxiety disorders, agitation, seizures, alcohol withdrawal, and acute coronary syndrome due to cocaine use. It also alleviates chemotherapy-induced vomiting and nausea and is used during surgery and for mechanically ventilated persons. Popular brand names of this drug include Ativan, Tavor, Temesta, and more.

This drug is a benzodiazepine and acts on the central nervous system, producing a calming effect by enhancing gamma-Aminobutyric acid or GABA, the primary inhibitory neurotransmitter in the brain. Recovering addicts and their support system should know as much about potentially addictive substances as possible—if you or your loved one is recovering from addiction, here are things to know about lorazepam.

What Is the Half-Life of Lorazepam?

Classified under Schedule IV, the U.S. government considers it as having a lower risk of dependence than Schedule II or III drugs like fentanyl, morphine, barbiturates, and others. However, it doesn’t mean that lorazepam is entirely safe—it can be habit-forming, so it is only prescribed for short-term use. Ceasing lorazepam use can lead to withdrawal.

On average, the half-life of unconjugated lorazepam is 12 hours. The drug’s primary metabolite, lorazepam glucuronide, lasts about 18 hours.

How Long Does Ativan Last?

Although Ativan and other brands of lorazepam are fast-acting, they have a long half-life. The concentration of lorazepam in the body decreases by half every 12 hours, so a person who takes unusually high doses of it will have it in their system for more than a day. Ativan could be present in the body for up to nine days after the person’s last use.

Know that drug screens for employment or other purposes will test positive for Ativan, so you must disclose your prescription to the testing laboratory. Doing so allows them to interpret the test results accurately.

Blood and Urine Samples

A blood test can detect the presence of Ativan as early as six hours after ingestion. It can also detect this substance for three days after the last use, and the detection window can be longer for people who take lorazepam at higher doses and for more than three days. 

Meanwhile, urine screening can detect Ativan for much longer. Depending on how much lorazepam is in the body and how long the person has been using it, the detection window can last six to nine days or more. 

Hair and Saliva Samples

Like other substances, hair tests can show the presence of Ativan in the body. A hair sample can show the presence of lorazepam for up to 30 days after the last use. Saliva tests can also detect Ativan—up to eight hours after use—but laboratories rarely use this type of test to screen for benzodiazepines.

What Are the Uses of Lorazepam?

Ativan and other brands of lorazepam are primarily used for treating anxiety and seizures. It causes feelings of calmness and relief from anxiety, stops seizures, and is partially responsible for regulating sleep. Lorazepam acts on GABA receptors in the brain and depresses the central nervous system. It is a fast-acting medication, which makes it suitable for temporarily managing panic and anxiety attacks. 

How Long Does Lorazepam Last
How Long Does Lorazepam Last

However, combining lorazepam use with other depressants and alcohol consumption can cause fatal respiratory depression, something that recovering addicts should note.

What Side Effects Does Lorazepam Produce?

People who need to take Ativan can experience several side effects. These include sedation, weakness, instability, and nausea. Besides these, people who take lorazepam can experience the following:

  • Amnesia
  • Changes in appetite
  • Erectile dysfunction
  • Feelings of Depression
  • Headaches
  • Hypotension
  • Loss of orientation
  • Sleep apnea
  • Sleep disturbances

Besides the common side effects listed above, some people experience serious ones like:

  • Seizures and motor restlessness
  • Irregular or jerky movements
  • Spasms, contractions, or tremors
  • Respiratory depression
  • Suicidal ideation or attempts

Ativan, like all benzodiazepines, causes physical dependence. If a person takes lorazepam daily as a psychotropic drug, suddenly stopping its use can produce seizures, vomiting, sweating, and the other side effects listed above. Furthermore, stopping therapy after months of daily intervention can cause agitation, insomnia, and depressive feelings to return.

Lorazepam Tolerance and Dependence

Approximately one-third of individuals who use benzodiazepines like lorazepam for longer than four weeks exhibit withdrawal symptoms after ceasing to take it daily. People who take higher doses of the drug, or those who take it for long periods, are at risk of developing a benzodiazepine dependence. What’s more, benzodiazepines with a shorter half-life like alprazolam, lorazepam, and triazolam are the most likely to cause dependence.

Regular consumption of benzodiazepine causes users to develop tolerance. People who use Ativan and other brands of lorazepam for anxiety initially experience drastic relief—their panic symptoms go away, their insomnia disappears—but these return gradually. After approximately four to six months of regular use, this drug’s efficacy declines.

For persons who need regular treatment of longer than four to six months, it may be necessary to increase the dose to maintain the drug’s effects. This drug is not suitable for long-term epilepsy management since lorazepam tolerance also causes the patient to develop a tolerance for the drug’s anticonvulsant effects.

An increase in the dosage could overcome the tolerance, but the patient may subsequently develop a tolerance for the higher dose. In this case, the adverse effects would keep persisting with higher doses of the drug.

How to Prevent Lorazepam Dependence

Tolerance to benzodiazepines is a complex process. It involves the downregulation and alteration of the brain’s GABA receptors and changes in the user’s gene expression, among others. Simply put, benzodiazepines chemically alter the brain.

It is also highly likely for users to become dependent on lorazepam compared to other types of benzodiazepines. This drug’s relatively short serum half-life and its inactive metabolite could cause withdrawal and next-dose cravings. It can also reinforce the user’s psychological dependence. The smallest tablet strength of 0.5 milligrams is already enough in most cases.

It is vital for health care providers and a patient’s loved ones to ensure that the user isn’t at risk for developing dependence on lorazepam. One way to ensure they don’t develop a dependence is by using this drug in the short term, at the smallest dose possible. For cases that need long-term use of this drug, experts recommend a dose taper of weeks or longer, depending on the duration, degree of dependence, and the individual.

A person coming off the long-term use of lorazepam can reduce withdrawal symptoms by gradually switching to diazepam and initiating dose reductions on the second drug. People who successfully switch to diazepam don’t feel the dose reductions since this substance has a longer half-life of 20 to 200 hours.


Taking lorazepam is habit-forming; it is a Schedule IV drug in the U.S. People prescribed this drug shouldn’t take larger or more frequent doses than what their doctor recommends. A person with anxiety or insomnia who is also recovering from substance abuse should inform their doctor about their condition. It is because lorazepam can cause both tolerance and dependence in long-term users. Informing their doctor of their circumstances enables the latter to modify their treatment schedule accordingly, which helps them recover from their condition without relapsing or forming a new addiction.