Arieli,
As a foreigner the cops in Thailand love to shake you down for money. Depending on how much you smuggle in and what the political situation is right now they might even try to make an example of you. Go to pharmacies-you can get almost anything you want (they usually only restrict strong pain killers-percoset, etc). And if you feel like buying weed or other recreational drugs that you will be offered, be weary. Lots of times they are cops or are working with cops to shake you down. Enjoy the beach, OTC gear and if you're single the numerous working girls.