I wore the patch for the entire cruise and the only side effect was dry mouth. I drank some alcholic drinks and no side effects. But, the night we had very rough seas the patch did me no good. I threw on my relief band and went to bed. I'd say the patch is probably 90% effective unless the seas are very rough. The seas were so rough that night that most people on the ship couldn't stand up to walk!! I would cruise again in a second, but I'd take my relief band and patch with me.