"I have never personally taken this medication. However, my mother recently was prescribed to Marinol after other medications provided no relief from chemo induced nausea. Her first dose took about 3 hours to kick in (which is a long time when you're nauseated) but after that she's been a brand new person. I'm guessing it takes those first few hours to get fully in your system. She takes it twice a day and has had little to no nausea."