I've taken two cruises to Mexico (one was Mexican Riviera - Cabo, Mazatlan, Puerto Vallarta) the other we stopped in Cozumel while in the Caribbean. I actually purchased meds in Mazatlan and Cozumel. Bought Soma (about $40 for #120, Vicodin - $60 for 90 5/500 and Bentyl which was like $8 for a box of 48) The Soma and the Bentyl were on the shelf, and at first when I asked about the Hydro they said they couldn't sell it, but when I rephrased and asked if they could how much would it be?, he got the bottle out...) Codeine and Hydro are regulated there to some extent so while they will sell it don't expect the same prices.

Cruise ships are the best - I packed my meds (3 bottles of Soma, the Vicodin I took an old Rx bottle from home and put them in there in case of any questions) in a Ziplock in my cosmetic bag, (where I also conveniently carry my perfume). They'll take all luggage but your carry-on off the ship the night before. We filled out our little customs form - it didn't ask about meds to declare, so I didn't--- got off the ship, walked through Customs, handed them the form, picked up our luggage, and off we went.

From what I've read, going through TJ is the most dangerous way to get meds because the border guards are looking for it. On a cruise ship, there's so much freaking luggage up there all at once -- I heard from a more experienced cruiser that they'll walk a dog around them and that's about it. I'd say if you have empty bottles take them with you just to be on the safe side... have a wonderful trip, by the way!!!