I don't know about niacin, but gabapentin, by prescription, helps with chills and sweating. I agree with C Girl, above-- without a program you will end up back where you started.
Good luck-
Hi, Congrats on getting clean. I used to be addicted to heroine, so i've been in your boat before. I just celebrated my 2 year clean date. Please find a local Narcotics Anonymous meeting that is close to your house. They can help you there. www.na.org