Please note the instructions provided is for all travel into Thailand, not only for medical treatment purposes.
During your flight, you will be asked if Thailand is your final destination, and if so an “arrival and departure card” will be given to you to complete – keep in mind they are joined together. Please consider adding a pen to your carryon as you will need one to complete and not all flight attendants have pens to loan.
I usually complete my immigration paperwork as soon as I receive them. The cards are repetitive and will require you completing your family name, first and middle name, date of birth, gender, nationality, passport number and flight number. Whatever you do, don’t wait until you are in the immigration control line before you pull out your pen, the line may move faster than you think and you will be sent to the end of the line.
A visa is not required for travel from the US but please follow this link to the Ministry of Foreign Affairs for the Kingdom of Thailand to see if a visa is needed for your country. http://www.mfa.go.th/main/en/services/123
Once you get to the immigration area, please note the overhead signage for Thai passport carriers and foreign passport carriers. Have your passport and your arrival – departure card ready, it will be inspected by the immigration officer who with then stamp with a 30 day visa. They will also take a photo of you. If you are required to have a visa (again US passport holders are not) there is an area near the immigration area where you can apply for one.