I take 2mg low dose naltrexone. My rheumatologist prescribed it and I get it from a compounding pharmacy. It is an off label use so it is not covered by insurance. My pharmacy charges $60 for a one month supply. I have peripheral spondyloarthritis and undifferentiated connective tissue disease. She did say that it's typically used for fibromyalgia but said I could try it. I had to titrate up to the 2mg. At first I didn't really notice that it was doing anything. I stopped it for a while and definitely felt worse so I started again. I guess it does make a difference but it hasn't helped completely. It just seems to take the edge off. I asked her if we could increase the dosage a while ago but she wouldn't. I may ask again. I've been on it for about 2 years.