I have to say I am becoming a little tired of answering this question, which I think I have answered at least 5 times in the not too distant past!( Try keying in "Sea- sckness" in the search topic box!) However I will deal with it once again. The Medical Centre will administer a Phenergan injection which you need at the first onset of symptoms.
Yes you can have medication on board, bu it's expensive. See your own GP who will probably prescribe somethin.