Other medications

What is low-dose naltrexone?

Low-dose naltrexone (LDN) is a small dose of naltrexone, a medication commonly used to treat opioid use disorder (OUD). Learn more about low-dose naltrexone.

Ophelia team
Low dose Naltrexone
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Mena Soliman, NP

Low-dose naltrexone (LDN) is a small dose of naltrexone, a medication commonly used to treat opioid use disorder (OUD). The low-dose version of the drug is administered in amounts as small as 1/30th the typical dose of naltrexone. Currently, LDN is used to treat a number of chronic conditions, though this application is still considered “off-label” as it has not yet received FDA approval.

Uses of low-dose naltrexone

LDN therapy can be used to alleviate long-lasting pain. For example, a practitioner might prescribe small doses of naltrexone when a patient has experienced pain for more than 90 days and hasn’t responded to other treatment methods.

While researchers are investigating the efficacy of LDN for a broad range of ailments, it’s most commonly used to treat the following conditions:

  • Fibromyalgia
  • Chronic fatigue syndrome
  • Autoimmune thyroid disorders
  • Crohn’s disease
  • Multiple sclerosis
  • Cancer
  • Gulf War syndrome
  • Myalgic encephalomyelitis
  • Long COVID
  • Alzheimer’s disease
  • Diabetic neuropathy
  • Parkinson’s disease

What is LDN used for compared to regular naltrexone?

While naltrexone has been used to treat alcohol use disorder and OUD for more than three decades, researchers are finding that extremely small doses of the drug may be effective for controlling the symptoms of other conditions. The FDA first approved naltrexone in 1984, marking its safety and efficacy. In this application, naltrexone works by blocking and reducing how the body’s opioid receptors work, preventing people who use drugs from experiencing euphoric effects that reinforce behaviors of addiction.

For OUD, naltrexone can be taken orally or by injection. Naltrexone pills are round or oval and may come in a variety of colors, such as white or beige. The tablets are commonly prescribed in doses of 25, 50, or 100 mg, and may have the dosage and manufacturer’s logo imprinted on them.

When used for the treatment of chronic conditions, LDN is given in doses as low as 1.5 mg. Typically, patients can receive the medication in liquid or tablet form from a compounding pharmacy, which will have the ability to create ultra-low doses of naltrexone. Depending on the patient’s response to the initial dosage, prescribers may increase doses over time, usually to a dose of about 6 to 8 milligrams.  

Naltrexone in its standard doses works as an antagonist to prevent the euphoric feelings of opioids by binding to opioid and endorphin receptors, which prevents euphoria-producing molecules from attaching. Researchers are still exploring how LDN alleviates pain, but they have several theories:

  • LDN has anti-inflammatory effects, which can minimize inflammation or swelling in the nervous system that contributes to pain
  • LDN can support the immune system to help people with autoimmune conditions stay healthy
  • LDN blocks proteins that may trigger symptoms of conditions related to the nervous system, including chronic fatigue syndrome and fibromyalgia
  • LDN blocks certain receptors in the body that are linked to pain and enables the release of endorphins

Low-dose naltrexone side effects

LDN appears to be tolerated well by most patients, but certain side effects are possible. Mild side effects include dizziness, nausea, vomiting, joint and muscle pain, anxiety or nervousness, fatigue, and sleep challenges. Headaches, mild allergic reactions, abdominal pain, and sexual side effects may also occur.

Like most medications, naltrexone also has a slight risk of serious side effects. Although rare, the following complications could occur:

  • Depression
  • Liver problems, including hepatitis
  • Severe allergic reaction
  • Opioid withdrawal symptoms, if an opioid is taken within 10 days of starting naltrexone
  • Opioid overdose, if opioids are taken in conjunction with naltrexone or shortly after stopping it

While long-term side effects of LDN are uncommon, severe side effects—such as increased blood pressure or heart rate—could also occur. These typically happen at higher doses.

Alcohol and other certain drugs should be avoided when taking LDN, including opioid pain relievers, such as oxycodone and tramadol. Because naltrexone can inhibit the enzymes that help the body metabolize drugs, it should not be taken in conjunction with CYP450 substrate medications, including diazepam, sildenafil, and certain chemotherapy drugs, among others.

Naltrexone vs. other OUD treatments

While naltrexone in its complete doses is a widely used treatment for OUD, it is only one option available for medication-assisted treatment (MAT). Other options include Suboxone®, a brand name of generic buprenorphine-naloxone drug, as well as naloxone alone (important safety information). Both naltrexone and naloxone work as antagonists that bind to opioid receptors, but naltrexone lasts longer than naloxone.

Also known as Narcan, naloxone has a half-life of 1 to 1.5 hours in the body. For this reason, Narcan is generally used as an emergency treatment for acute opioid overuse, while naltrexone is on a long-term basis for opioid detox.

Suboxone, on the other hand, combines naloxone with buprenorphine to reduce the risk of medication misuse. It has a half-life of about 40 hours, so its benefits extend further than that of Narcan. When used together, the two drugs effectively reduce cravings for opioids and block their effect while also reducing the risk of overdose. Suboxone is known for high success rates when combined with holistic approaches to MAT, like therapy and counseling.

Further, while LDN remains in its research phase and is still currently being used as an off-label treatment for chronic conditions, Suboxone’s use for OUD was approved by the FDA over 20 years ago. There are hundreds of published researchers confirming its efficacy. It’s also widely available: Suboxone can be prescribed in any treatment setting by licensed medical providers, and it can be picked up from most local pharmacies.

Understanding the latest science-backed treatments for OUD

We know that medications for addiction treatment (MAT) are safe and effective—and considered the gold standard of care. That’s why Ophelia’s clinicians stay on top of developments that can help their patients. We share our research and clinician publications to ensure our results and the latest findings in our field are accessible to all. Why? Because informed patients are empowered patients.


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