If you are planning on coming to Thailand and need to bring personal prescription medicines, there are restricted medications that cannot be brought into Thailand.
If your prescription has any of the ingredient’s listed on the Table of Controlled Narcotic Drugs IN THAILAND, you will NOT be allowed to bring them into Thailand.
From the Royal Thai Embassy in Stockholm Sweden website, you can find information and links what you can and cannot bring into Thailand.
Table of controlled Narcotic Drugs in Thailand (downloadable PDF file)