Once sea sickness takes hold it's usually too late to do much about it. I am very sensitive to motion of a ship so I take 1/2 a non drowsy dramine right before bed starting the night before the ship leaves. I only take 1/2 because I only weigh about 100lbs so a full tablet is too much for me. The non drowsy formula still makes me sleepy; this is why I take it before bed it acts as a sleep aid as well ,and keeps me from getting queezy the next day. I have had alcohol on cruises while this is in my system I find it makes me perhaps more tired so I drink less alcohol. Hope this helps.