An old opioid antagonist repurposed at tiny doses as an immunomodulator — widely used off-label for autoimmune conditions, chronic pain, and long-COVID recovery.
Naltrexone is an opioid antagonist FDA approved at 50 mg/day for alcohol use disorder and opioid dependence. At low doses (1.5–4.5 mg/day), it shifts to an entirely different mechanism: transient opioid receptor blockade followed by upregulation of endogenous opioids (endorphins, met-enkephalin) and modulation of TLR4-driven inflammation.
LDN is prescription-only. It’s not FDA approved at low-dose and is used off-label for autoimmune disease, chronic pain, fibromyalgia, and more recently for post-COVID chronic fatigue.
Naltrexone FDA approved at 50 mg. LDN (1.5–4.5 mg) is off-label. Prescription only; typically compounded by specialty pharmacies. Not WADA prohibited.
At low doses, naltrexone briefly (4–6 hours) blocks opioid receptors. The body’s compensatory response — upregulating endorphins and enkephalins — outlasts the blockade and is the primary therapeutic mechanism.
Blocks toll-like receptor 4 on microglia and macrophages — reducing neuroinflammation and pro-inflammatory cytokine output. This is the leading mechanism for its effects on fibromyalgia and neuroinflammatory pain conditions.
Shifts Th17/Treg balance toward regulatory tone. Explains benefits seen in autoimmune conditions like Hashimoto’s, Crohn’s, and MS.
| Condition | Evidence |
|---|---|
| Fibromyalgia | Younger et al.: significant pain reduction; strongest evidence base among non-opioid alternatives |
| Crohn’s disease | Small RCTs: remission improvements |
| Multiple sclerosis | Mixed but positive small trials; symptom improvement, not disease modification |
| Hashimoto’s | Anecdotal and open-label: reduced antibody titers, symptom relief |
| Chronic pain (non-fibro) | Broad off-label use; modest evidence |
| Long-COVID | Case series and open-label studies suggest benefit for fatigue, brain fog, pain; larger trials underway |
Build your protocol, log every dose, monitor your body's response, and get reminders so you never miss a dose.
Start Tracking FreeLDN is generally very well tolerated — side effects are usually mild and transient.
If you need surgery, stop LDN at least 3 days prior so anesthesia and post-op opioids work normally.
Use our free peptide calculator to figure out your reconstitution volume, draw amount, and syringe units.
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Low Dose Naltrexone (LDN) is a prescription medication. StackTrax does not sell, prescribe, or facilitate purchase of prescription drugs.
Find a clinician who can order baseline lab work, screen for contraindications, monitor your response, and adjust dosing over time. Options to consider:
Before starting, you’ll typically want:
Avoid sources that offer prescription medications without labs, medical history, or licensed-provider oversight. If a telehealth service promises a prescription after a 5-minute questionnaire, that’s a red flag.
Build your protocol, log every dose, monitor your body's response, and get reminders so you never miss a dose.
Start Tracking FreeDisclaimer: This guide is for educational and informational purposes only and is not intended as medical advice, diagnosis, or treatment. The compounds discussed are not FDA approved for human use. Always consult a qualified healthcare provider before starting any new supplement or peptide protocol. StackTrax does not sell peptides or supplements directly — purchase links go to third-party vendors. StackTrax is not responsible for the products, quality, or business practices of any third-party vendor. This page contains affiliate links — StackTrax may earn a commission on purchases at no extra cost to you.
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StackTrax guides cover peptides and compounds that are not FDA-approved for the uses discussed. The dosing, reconstitution, and safety information is compiled from published research and community protocols for educational purposes only.
Before using any compound mentioned here, consult a qualified healthcare provider. StackTrax does not sell, prescribe, or recommend these substances for personal use.
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