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LDN for Fibromyalgia & Chronic Fatigue Syndrome

August 10th, 2025
LDN3

By Adrienne Dellwo | Updated on July 24, 2025, Published in verywell
(with some modifications)

Studies on low-dose naltrexone show promise in treating conditions like fibromyalgia and chronic fatigue syndrome, as the medication might offer anti-inflammatory and immune-regulating properties. While small studies suggest positive outcomes, more research evidence is needed to support claims of naltrexone’s benefits.

How Does Low-Dose Naltrexone Work?

At a standard dose of 50 to 100 milligrams (mg), naltrexone blocks the effects of opioid pain relievers by binding to opioid and endorphin receptors. However, researchers are still investigating exactly how lower doses work for conditions like fibromyalgia and chronic fatigue syndrome.

Possible mechanisms include:

  • Blocking certain proteins that worsen symptoms of fibromyalgia and chronic fatigue syndrome in the nervous system
  • Reducing inflammation in the nervous system, acting as an anti-inflammatory
  • Balancing the immune system, potentially aiding with immune-related illnesses.
  • Temporarily blocking pain receptors and prompting the release of endorphins, the body’s natural painkillers

Low-Dose Naltrexone Uses

At very low doses, naltrexone may help people with fibromyalgia, chronic fatigue syndrome, and other conditions. Here is a closer look at low-dose naltrexone benefits and uses:

  • Fibromyalgia: This condition is characterized by pain, fatigue, and other symptoms. Studies suggest LDN may reduce pain and improve quality of life, though more research is needed. It’s sometimes used off-label, meaning for a condition not approved by the Food and Drug Administration.
  • Chronic fatigue syndrome (CFS): This condition involves fatigue, unrefreshing sleep, and neurological issues. It is also known as myalgic encephalomyelitis. LDN may reduce symptoms, possibly due to its effect on neuroinflammation.
  • Multiple sclerosis (MS): This autoimmune disorder causes nerve damage. LDN may improve fatigue and quality of life, but more compelling research evidence is needed to establish a benefit.
  • Long COVID: This refers to prolonged COVID-19 symptoms. Some studies suggest LDN could help reduce symptoms and improve well-being, but larger studies are needed.
  • Crohn’s disease is a chronic inflammatory bowel disease. LDN appears safe for use, but more research is needed to verify if it’s effective.
  • LDN has also been studied for its anticancer properties, but so far, there is no research that supports the use

Other Uses for Low-Dose Naltrexone

Research shows some promise for low-dose naltrexone in treating these other conditions:

  • Alzheimer’s disease
  • Diabetic neuropathy
  • Gulf War syndrome
  • Parkinson’s disease
  • Autoimmune thyroid disorders
  • Relapsing major depressive disorder

How Do You Take Low-Dose Naltrexone?

For fibromyalgia or chronic fatigue syndrome, naltrexone is typically administered in doses of 4.5 mg or less. Often, treatment begins at 1.5 mg or less and increases to 3 mg, then to 4.5 mg.

Higher doses haven’t demonstrated the same symptom-reducing effects for these conditions.

Research shows that the drug seems safe for long-term use. As long as naltrexone benefits you, you can take it on an ongoing basis.

How Long Does It Take for Low Dose Naltrexone to Work?

In clinical studies, patients taking low-dose naltrexone to treat chronic pain reported symptom relief in one to three months.

What are the Side Effects of LDN?

While LDN appears to be well-tolerated, known side effects of naltrexone include:

  • Dizziness
  • Headache
  • Insomnia (problems sleeping)
  • Vivid dreams
  • Nausea
  • Decreased appetite
  • Joint pain
  • Muscle cramps
  • Tooth pain
  • Anxiety

Considerations

People with kidney disease or liver disease may need to speak with their doctor before starting LDN. Those who are pregnant or breastfeeding should also speak with their doctor before starting this medication.

Key Interactions with Low-Dose Naltrexone

You should avoid alcohol and certain medications when taking low-dose naltrexone.

For example, with opioid pain relievers, combining LDN with drugs like codeine, tramadol, morphine and oxycodone may cause withdrawal symptoms.

Cytochrome P450 (CYP450) is a protein that helps your body metabolise drugs. Because naltrexone can inhibit these enzymes, caution is advised with drugs including:

  • Amlodipine
  • Buspirone
  • Diazepam)
  • Erythromycin
  • Viagra (sildenafil)
  • Warfarin
  • Thioridazine
  • Certain chemotherapy drugs

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