Can ativan (lorazepam) stop working after four hours?

Unlikely: It takes 5 half lifes to have a drug eliminated from your system and Ativan (lorazepam)'s half life is 12 to 14 hours. Oral Ativan (lorazepam) takes about 1 hour for it to reach its peak concentration in your blood though. Everyone responds to this medication differently though. I am just explaining to you the pharmacokinetics.

Ativan (lorazepam) : Ativan (lorazepam) is a benzodiazepine with a half life of 14 hours. This means for half of a dose of Ativan (lorazepam) to be used up by your body it would take 14 hours so it would be very unlikely wear off after only 4 hours

Yes! Memory problems: with Ativan- be careful. Without question, ssri's: paxil (paroxetine), (paroxetine) (fluoxetine (Prozac), zoloft etc) are anxiety top shelf treatment. Benzos have too many side effect tendencies with anxiety and withdrawal precisely because they are too short acting and the peaks and valleys in blood levels make side effects easy to happen. This can lead to dependence/addiction.Ask your doc about safer adjunct to paxil (paroxetine).