Dutasteride is perscribed off label for hair loss. Basically, doctors can perscrib any approved drug for any condition they want if they believe it to be helpful.
In the US you can visit medicalwellnesscenter.com to get a legit prescription for dutasteride online, which can be filled at any legit pharmacy in the country. Many on these forums, including myself have done this. They charge 50 or 75 bucks for the consult.
Better to visit your regular dr if you can, but they don't always agree with, or understand, what you're trying to accomplish, or are willing to do.