Hello rob2145. You will be fine. The Ativan (fast acting Benzodiazepine) has a 1 to 2 hour time to peak upon taking the drug. It has a half life from 6 to 12 hours. How long does Ativan last? How long does lorazepam last? Is there a difference between the two? If you’re taking the drug Ativan for anxiety, it’s important that you know how long it lasts so you can work with your doctor to figure out how much you should take and how often you should take it. I use Ativan on an as needed basis. I usually take 2mg when I’m having a panic attack. It removes the effects of the panic attack, but other wise allows me to function with full ability. How long do withdrawals last? (Lorazepam) Ativan withdrawal symptoms start quickly after the last dose due its half-life. Most acute side effects hit 3-4 days out. (Lorazepam) Ativan withdrawal symptoms start quickly after the last dose due its half-life. How long does Ativan last? Once Ativan kicks in, it might last for six to eight hours – again, it depends upon your body and your metabolism. Ativan may be different because it does not stay in the body as long. I broke my dose into 3x a day since I already have a steady level of the drug in my body & it wouldn't make me super sleepy. I broke my dose into 3x a day since I already have a steady level of the drug in my body & it wouldn't make me super sleepy. Hi people, I am contemplating taking some lorazepam tablets, and thought I should check first with people who may have experience using lorazepam. To find out more about how long the effects of Ativan will last for you talk to your doctor. He will be able to gauge more accurately the effects of the drug based on your past history of medication use and your situation.