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Low Dose Naltrexone or LDN

What is Naltrexone?

Most commonly, Naltrexone is an opiate antagonist (blocker) that is given intravenously or intra-muscularly in emergency situations to reverse opioid overdoses.  It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of addictions to opioids and alcohol. 

What is Low Dose Naltrexone (LDN)?

This is the use of an oral formulation at 1/10th the dose of rescue Naltrexone.  Generally, we start out at 1.5mg and can go up to 4.5mg daily.  This is taken at night as it has some sedative effects and can help with sleep.  It has been used by Functional Medicine providers for years safely as an off-label usage, meaning that is has not been approved by the FDA for specific conditions, but is generally accepted as safe. 

Summary of Action

The summary of 10 years of research into LDN shows that:

  • Naltrexone is an antagonist for the option/endorphin receptors

    • this causes increased endorphin release​

  • Increased endorphins modulate the immune response

    • this reduces the speed of unwanted cells growing​

  • Suppresses cytokine modulated immune system​​​

  • Antagonizes TLR mediated production of NF-kB

  • Reduces inflammation

  • Potentially down-regulates oncogenes

Functional Medicine Uses of LDN

Here at Rejuvenate, we focus on autoimmune diseases such as multiple sclerosis (MS), Psoriasis, Crohn’s Disease and Rheumatoid Arthritis.


Low Dose Naltrexone (LDN) has been demonstrated to reduce symptom severity in conditions such as fibromyalgia, Crohn’s disease, multiple sclerosis, psoriasis and complex regional pain syndrome. There is growing evidence that LDN may operate as a novel anti-inflammatory agent in the central nervous system, via action on microglial cells. These effects may be unique to low dosages of naltrexone and appear to be entirely independent from naltrexone’s better-known activity on opioid receptors. 


As a daily oral therapy, LDN is inexpensive and well-tolerated. There is great promise of efficacy and studies on the use of LDN for chronic disorders are ongoing. Published trials have low sample sizes, and few replications have been performed. LDN has been used in Functional Medicine for many years and there have been great results when used in combination with elimination diets and appropriate supplementation.

LDN Treatment Protocol

LDN Starting Dosage

  • 1.5mg, 1 capsule at bedtime for 3 to 7 days

  • If tolerated, then proceed to 2 capsules at bedtime for 3 to 7 days

  • If tolerated, then proceed to 3 capsules at bedtime

  • LDN Maintenance Dosage is 4.5mg daily.

Side Effects


LDN has virtually no side effects. Occasionally, during the first week’s use of LDN, patients may complain of some difficulty sleeping, strange dreams or morning fatigue. This rarely persists after the first week. Should it do so, dosage can be reduced from 4.5mg to 3mg nightly

Cautionary Warnings

Because LDN blocks opioid receptors throughout the body for three or four hours, people using opioid medications, i.e. narcotics such as Ultram (tramadol), morphine, Percocet (oxycodone), Vicodin (hydrocodone) Duragesic (fentanyl) patch or any codeine-containing medication should not take LDN until such medicine is completely out of one’s system.


Patients who have become dependent on daily use of narcotic-containing pain medication may require 10 days to 2 weeks of slowly weaning off of such drugs entirely before being able to begin LDN safely.

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