Anything that is Thai made is generally Legit, as the pharmacy buys stright from the manufacturer, but be that extra bit careful when it comes to anything that is brought into Thailand from elsewhere as its not often legit. For instance, Primo in Thailand has a bad name. I'm sure a lot of it is okay, but have spoken personally to a number of fellow English who bought Primo that wasn't. I'd say, do your research before going into the pharmacy so you know exactly what your looking out for on the package etc before you buy.