Naltrexone is in a class of drug known as an opiate antagonists. It is normally used in treating addiction to opiate drugs such as heroin or morphine. The daily dose used for this purpose is usually between 50 and 300mg per day.
LDN refers to daily dosages of naltrexone that are approximately 1/10th of the typical opioid addiction treatment dosage. At the low dosage level, naltrexone exhibits paradoxical properties, including analgesia and anti-inflammatory actions, which have not been reported at larger dosages. The mechanism of action of Naltrexone, in autoimmune diseases, is poorly understood. The benefits of the drug are possibly due to the temporary inhibition of endorphins. This results in a reactive increase in the production of endorphins, which should result in a reduction of painful symptoms and an increased sense of well-being.
LDN has been used in the treatment of many autoimmune diseases, and has been demonstrated to reduce symptom severity in conditions such as fibromyalgia, Crohn’s disease, multiple sclerosis, and complex regional pain syndrome.
LDN has been tested experimentally in a small number of chronic pain conditions. One such condition is fibromyalgia (FM). FM is a chronic pain disorder that is characterized by diffuse musculoskeletal pain and sensitivity to mechanical stimulation as well as profound fatigue, cognitive disruption, and sleep difficulty. Two separate clinical trials demonstrated that LDN may be an effective treatment for FM.
Treatment is started at an ultra-low dose and increased gradually over a period of weeks. The starting dose can vary from 0.5mg to 1.5mg and is usually increased over 4 to 8 weeks to about 4 mg.
Younger, J., & Mackey, S. (2009). Fibromyalgia symptoms are reduced by low-dose naltrexone: a pilot study. Pain medicine (Malden, Mass.), 10(4), 663-72.
Younger, J., Noor, N., McCue, R., & Mackey, S. (2013). Low‐dose naltrexone for the treatment of fibromyalgia: findings of a small, randomized, double‐blind, placebo‐controlled, counterbalanced, crossover trial assessing daily pain levels. Arthritis & Rheumatism, 65(2), 529-538.