Low-Dose Naltrexone (LDN 1.5-4.5mg)
What to know about Low-Dose Naltrexone (LDN 1.5-4.5mg): uses, side effects, interactions, and safety considerations for people taking it or caring for someone who is.
Low-Dose Naltrexone (LDN 1.5-4.5mg) is classified as Low risk (1 risk points) by AllMeds. It is a S4 medication under the TGA in Australia. Off-label use of naltrexone at micro-doses for chronic pain, fibromyalgia. Growing evidence. CAUTION: contraindicated with opioids.
Key Takeaways
- TGA Schedule: S4 in Australia
- Risk level: Low (1 points)
Scheduling and Classification
| Jurisdiction | Classification | Status |
|---|---|---|
| Australia (TGA) | S4 | Not PBS listed |
Risk Profile
Off-label use of naltrexone at micro-doses for chronic pain, fibromyalgia. Growing evidence. CAUTION: contraindicated with opioids.
How Low-Dose Naltrexone (LDN 1.5-4.5mg) is regulated
Low-Dose Naltrexone (LDN 1.5-4.5mg) is overseen by medicines regulators in each country. The rules below explain how it's scheduled, what oversight applies, and what to discuss with your doctor or pharmacist before starting, changing, or stopping this medication.
Australia TGA / PBS / State Schemes
Classified as S4 under the Therapeutic Goods Administration (TGA).
Clinical Evidence
- r/LowDoseNaltrexone — Patient experience community (2024)
Active community of LDN users sharing experiences. Common themes: fibromyalgia, autoimmune conditions, chronic pain. Anecdotal reports of benefit.
Anecdotal — self-selected positive reports, no controlled outcomes
- Low-dose naltrexone for chronic pain: systematic review (2018)
Systematic review finding preliminary evidence for LDN in fibromyalgia and chronic pain. Small trials, heterogeneous outcomes. More research needed.
Peer-reviewed but evidence graded as low quality
- Low-dose naltrexone for fibromyalgia — pilot RCT (2013)
Small RCT (n=31) showing LDN 4.5mg reduced fibromyalgia pain by 28.8% vs placebo. Stanford study.
Published RCT but very small sample size
- Peter Attia — LDN and autoimmune conditions (2023)
Discussion of LDN mechanisms (TLR4 antagonism, endorphin upregulation) and clinical applications. Notes it is well-tolerated but evidence base is thin.
Physician communicator — reasonable discussion of evidence gaps
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Important: This page is general health information, not personal medical advice. If you have questions about your medication — including starting it, stopping it, changing the dose, or combining it with something else — speak with your doctor or pharmacist. For an emergency or suspected overdose, call your local emergency number or poison information service immediately. Information is drawn from regulator and clinical guideline sources (TGA, FDA, MHRA, NICE, PBS, CDC); see our methodology for details.