It's not "addictive" really but it's a controlled substance because it can be abused. Don't worry about that now. Take what you need to mitigate chemo side effects. By all means, complain!
Don't get dehydrated is good advice. Also, don't go long periods without eating. Even if it is the last thing you feel like doing, eat a small snack at the first sense of nausea. My go-to food during chemo was dry mini-wheats. I would wake up super early in the morning, eat some dry cereal and then go back to bed for hours. I called it "getting up before the nausea."