I tend to get motion sickness pretty easily so I use meclizine, 25mg. It's cheap. Says it can make you drowsy so I take one every night. I start the night before the cruise and take for two days after I'm home. If it's really rough seas or I'm doing something in the port that might make me feel ill, I'll take another in the morning. Never had a problem. Even on the days when there are sickness bags hanging everywhere just in case.