From my experience there is a lot of hype surrounding drug use in SE Asia. Although there are areas that I wouldn’t even think about doing certain drugs (eg Bali) there are other areas that I believe are extremely ‘safe’ for taking drugs. Taking drugs in a foreign country can involve a lot more risks but the final choice is yours. Below is my brief experience with drugs in Thailand.
Most different drugs are available but tend to vary from place to place. Weed is everywhere and you will probably be offered it many times by locals while you are there. It is generally of poor quality but it is very cheap. Lots of pharmacies (apart from in big tourist areas) will sell you drugs like benzos and diet pills and occasionally other drugs like morphine etc. Up north opium is very readily available although fairly expensive compared to other drugs.
I did not hear of anyone getting busted while I was there but I heard rumors that $750US could get you out of just about any situation.
Just as an example of how easy drugs are to access, I stayed in a beach bungalow on one of the islands and weed, shrooms and even ecstasy were written on the specials board in plain sight! If you ordered weed it would either come with a bong or rolled into joints if you preferred. The shrooms came as either omelets or shake and ecstasy was in capsules (meant to be pure MDMA) or pills (unknown mixes). You could smoke weed openly in most accommodation and no one would seem to mind.
Just some suggestions for you if you do decide to take drugs over there:
Don’t travel with drugs (even just between towns)
You should be fine with mushrooms and weed but be extremely careful with drugs like ecstasy etc due to the danger of unknown contents.
Don’t buy off the street or in a club if you can help it, rather try and buy through your accommodation or even from other tourists as they are more likely to tell you the truth.
Only buy drugs just before you use them so you don’t have to store them.
Store them away from your gear eg. outside or some other deniable spot.
If you get busted with something immediately ask the officer if there is a ‘fine’ that you could pay rather than going to jail. It will be much cheaper and easier to pay off some local cop trying to make money than someone higher up when you end up in jail. Just remember though it is Thailand so barter with them!
Which ever drugs you end up doing, keep your doses low and don’t go too crazy. Wasting holiday time in a Thai hospital due to drug use is not fun, trust me
Hope this helps. Feel free to post up any more specific questions.