Medicines can be taken to thailand?

As i am planning a holiday to thailand,i take medicine for Thyroid. And for flight fear anxienty,i take Trika0.25mg (alprazolam) 1 or 2 tablets to be comfortable while the flight,is it possible to carry minmiun qantity with doctor prescription.Can any one tell about it .

Be very careful. Trika is Indian-made Alprazolam. It's on the watch list in Asia because of the massive amount of trafficking on the black market in Alprazolam and other benzodiazepines. Thailand now has become very very strict when it comes to drugs and psychoactive plants. You MUST carry your prescription and preferably a letter from your Doctor stating that you have been prescribed this drug for whatever condition you are suffering from. As long as you do that, you should be safe. But don't even think about bringing in Trika to Thailand without a prescription. You can get into very serious trouble.

EDIT: It sounds like you are living in India too. If that is the case, I'm sure you've read in the papers about the NCB busting this huge online drug trafficking ring a couple of weeks ago. They were selling stuff like Trika, Nitrosun (Nitrazepam), CalmPose (Diazepam), Fortwin (Pentazocine) and Tidigesic (Buprenorphine) without prescriptions and shipping them to the US from Coimbatore. Ever since that case, the laws in this region have become even stricter. Better to be safe than sorry so speak to your doctor and ask him if he can write a note (on his letterhead) addressed to "Whomever it concerns". He should then state the reason why he gave you Trika. Carry that letter AND the prescription with you if you are planning to bring any quantity of Trika or any of the other drugs listed above into Thailand. That is my honest recommendation to you.

if its prescription then its fine

You will probably be fine if you take small amounts and you have a prescription, but customs can be a pain sometimes so you can never be sure. Obviously with the Xanax (the alprozolam), they might possibly suspect you were inteding to take it recreationally, but with that small a dose, and only taking a few tablets with you, it shouldn't be that much of an issue.

It would be best to take the tablets before the flight both there and back, and keep the tablets for the return flight in your main luggage. Just as a precaution - customs can be really unreasonable sometimes. And make sure you have your prescription slip. You will probably be fine.