Hi there, As far as I know, it's not advised injecting ativan. It's just not safe. I'm on this medicine and I take 0.5 mg of Lorazepam (Ativan) by mouth with a glass of water once or twice daily. It takes about 30 minutes to kick in and once it does you will know. It really helps me when I feel really anxious and helps me relax. Also, when taken near bed time it can help you fall asleep a lot easier.