What Is Low Dose Naltrexone?

Naltrexone is an FDA-approved medication used at standard doses (50mg) to treat opioid and alcohol use disorders. Low Dose Naltrexone (LDN) refers to doses typically in the range of 1.5mg to 4.5mg — far below the approved therapeutic range. At these lower doses, it works through an entirely different mechanism, with growing interest in treating immune and inflammatory conditions.

Because no pharmaceutical company makes naltrexone in low doses, LDN is only available through compounding pharmacies with a valid prescription.

How LDN Works

At low doses, naltrexone is thought to briefly block opioid receptors, triggering a rebound increase in the body's natural endorphin production. It also appears to modulate microglial activity in the central nervous system — reducing neuroinflammation — and may influence toll-like receptor 4 (TLR4) signaling, which plays a role in immune regulation.

What Conditions Is LDN Used For?

LDN is prescribed off-label for a wide range of conditions involving immune dysregulation, chronic inflammation, or chronic pain. Common uses include autoimmune conditions such as Hashimoto's thyroiditis, lupus, rheumatoid arthritis, and multiple sclerosis. It's also used for Mast Cell Activation Syndrome (MCAS), fibromyalgia, chronic pain, Crohn's disease, IBD, Long COVID, and POTS and dysautonomia.

Most uses are off-label. The evidence base varies — some conditions have small but promising clinical trials, others are supported primarily by patient experience and practitioner observation.

Side Effects and Tolerability

Most patients tolerate LDN well. The most commonly reported side effect is vivid dreams or disrupted sleep, particularly in the first few weeks. This often resolves on its own or with a dosing time adjustment. Some patients start as low as 0.5mg and titrate up slowly.

LDN should not be taken by anyone currently using opioid medications — the interaction can precipitate withdrawal.

How to Get LDN

You need a prescription from a licensed provider. LDN is prescribed by functional medicine doctors, integrative practitioners, neurologists, and rheumatologists. A compounding pharmacy then fills the prescription in the exact dose specified — typically as an oral capsule or liquid. Prices generally range from $30 to $80 per month depending on dose and pharmacy.

Bottom Line

LDN is one of the most versatile compounded medications available, with a growing evidence base across multiple hard-to-treat conditions. Compounding Finder helps you compare LDN prices from licensed U.S. pharmacies. Submit your prescription details and receive quotes within 1–2 business days.