low-dose naltrexone

Low-dose naltrexone (LDN) refers to the use of naltrexone at doses approximately one-tenth or less of the standard dose used for opioid or alcohol dependence, typically around 1.5–4.5 mg daily compared to the usual 50–100 mg daily[1][2][4]. Naltrexone is a synthetic opioid receptor antagonist originally developed and FDA-approved for treating opioid and alcohol use disorders. At low doses, however, it exhibits unique pharmacological properties distinct from its high-dose effects. The mechanism of action for LDN appears multifaceted: - It acts as a competitive antagonist at μ-opioid, κ-opioid, and δ-opioid receptors[4]. - At low doses, it may paradoxically upregulate endogenous opioid production and modulate glial cell activity in the central nervous system[2][3]. - LDN is thought to exert anti-inflammatory effects by modulating microglial cells and reducing neuroinflammation[2][3]. LDN has been studied off-label in various chronic conditions including fibromyalgia, Crohn’s disease, multiple sclerosis, chronic pain syndromes (such as complex regional pain syndrome), autoimmune thyroid disorders, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), post-COVID syndrome, postural orthostatic tachycardia syndrome (POTS), inflammatory skin disorders, cancer adjunct therapy (including melanoma and breast cancer), autism spectrum disorder symptoms management in some cases, pruritus in systemic sclerosis/autoimmune diseases,[1][2][3][6][9] among others. Despite promising early results—especially for fibromyalgia—most uses remain experimental due to limited large-scale clinical trials. LDN is generally well tolerated; side effects are uncommon but may include insomnia (~8%), vivid dreams/nightmares (<1%), nausea (<1%), headache or gastrointestinal upset; these are usually mild and transient[1][3].

Brand names

ReViaVivitrol

Other names

LDN