They do work. You have an accupressure point in your wrist which helps reduce or even eliminate nausea and the bands are made to put pressure on those points.
I tried them when I had morning sickness and mine only worked for 2 days then stopped :( I kept my receipt and took them back after a week of them not working. It was a nice relief though lol. The only thing I could keep down was a banana milkshake and finally after losing 20 lbs. in 2 weeks my doctor prescribed me meds. I'm 31 weeks now and just so happy I'm out of the morning sickness. I was sick up until 18 weeks. Good luck!