LDN
Low Dose Naltrexone — Immune Modulator & Anti-inflammatory
What is LDN?
Low Dose Naltrexone (LDN) uses naltrexone — an FDA-approved opioid antagonist used at 50mg/day for addiction — at much lower doses (1.5-4.5 mg/day) where it produces entirely different pharmacological effects. At low doses, naltrexone briefly blocks opioid receptors, triggering a rebound upregulation of endorphins and enkephalins and modulating microglia and TLR4 signaling in ways that reduce neuroinflammation and autoimmunity.
At standard doses (50mg), naltrexone continuously blocks opioid receptors. At low doses (1.5-4.5 mg), it produces a transient receptor blockade (lasting ~4-6 hours) followed by a compensatory upregulation of endogenous opioids that persists for 18-20 hours. Simultaneously, LDN inhibits Toll-like receptor 4 (TLR4) on microglia and immune cells — reducing neuroinflammation, pro-inflammatory cytokine production, and autoimmune activity through a non-opioid mechanism.
Research Evidence
Multiple clinical trials show LDN reduces fatigue, improves quality of life, and may slow progression in MS patients. Some neurologists use it as an adjunct to standard MS therapy.
Stanford RCT showed significant pain reduction in fibromyalgia patients on LDN vs placebo, with anti-inflammatory mechanism confirmed.
Pediatric and adult trials show LDN reduces Crohn's Disease Activity Index scores and promotes mucosal healing in Crohn's patients.
Evidence grades: Gold = RCT human data · Silver = consistent animal/human data · Bronze = limited or preliminary
Dosing Protocols
Reconstitution / Preparation
This compound does not require reconstitution — it is available as an oral or pre-mixed formulation.
Frequently Asked Questions
What conditions is LDN used for?
LDN is used off-label for multiple sclerosis, fibromyalgia, Crohn's disease, ulcerative colitis, chronic fatigue syndrome, lupus, psoriasis, and various autoimmune conditions. It is also gaining use in the biohacking community for neuroinflammation reduction, immune optimization, and as an anti-cancer adjunct. Because it is off-patent and inexpensive, there is limited pharmaceutical incentive for large clinical trials despite compelling smaller study data.
Can LDN be used for long COVID?
Growing interest in LDN for long COVID based on its neuroinflammation and microglial modulation mechanism. Several case series and small trials are underway. The TLR4 inhibition pathway is mechanistically relevant to the neuroinflammatory component of long COVID. No large RCTs yet, but LDN is being used by physicians treating long COVID patients with promising anecdotal results.
References
- [1]Younger J, Mackey S. Fibromyalgia symptoms are reduced by low-dose naltrexone: a pilot study. Pain Med. 2009;10(4):663-672.
- [2]Smith JP, Stock H, Bingaman S, et al. Low-dose naltrexone therapy improves active Crohn's disease. Am J Gastroenterol. 2011;106(10):1-6.
This profile was prepared using AI-assisted research synthesis. Citations are provided where applicable — verify with primary sources before clinical application.
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