There are docs in Thailand who give injections. I never get them there myself, because I get 2 large doses in the week before I leave the US and that keeps things going until I return home. I know you can also buy testosterone and syringes from some pharmacies in Thailand, but you don't want to do that because injecting yourself without physician supervision is unwise and dangerous. There was another BM from this board living full time in Thailand who did that. He was giving himself large doses thinking more was better. He passed away suddenly and I wonder if his injecting himself hastened his passing. Be smart and don't dose yourself.
When you get your first injection, you will feel a jolt that day. A few days after that ,libido, energy etc. return to where they were before and then you get weekly injections. It was a long time ago when I started, but I think it was maybe 3-4 weeks before I felt full effects. Every guy is different, however. Some guys get testosterone pellet injections which last several weeks, but my doctor said weekly injections remain the best treatment.
If you can, you need to start your treatments at home under doctor supervision about 4-6 weeks before your trip. That way, your motor will be humming when you arrive in BKK.
I recommend every guy over the age of 40 or so get testosterone treatments. It changes everything for the better.