Hi Desi,
Yes, you are right, Naltrexone is usually used for alcohol or drug dependence, but this is in high doses. In very small doses it seems to help with these other disorders, such as autoimmune. Where I could see it not working for RSD is for those who do take opiods--perhaps it might render them ineffective for the person, but I'm not sure it would at such a small dose. It would definately be considered "off-label" or experimental for RSD, but since Naltrexone is approved by the FDA, a doctor could apparently use their discretion. It does sound like there is a lot of controversy over its use. If you go to http://www.lowdosenaltrexone.org you can also read more about it.