Low-Dose Naltrexone (LDN)

Reviewed by: HU Medical Review Board | Last reviewed: April 2023

Naltrexone is a drug approved by the U.S. Food and Drug Administration (FDA) for opioid dependence and alcoholism. However, it is sometimes prescribed by doctors off-label. This means it is given to treat a different issue than the one the FDA originally approved it for. It also means the FDA has not yet determined the drug is safe and effective when used for an unapproved condition.1-3

Low-dose naltrexone (LDN) is used for a variety of health conditions: including:1-3

  • Multiple sclerosis
  • Complex regional pain syndrome
  • Fibromyalgia
  • Certain types of cancer
  • Crohn’s disease
  • Skin conditions

How does LDN work?

At FDA-approved doses, naltrexone blocks opioid receptors. This affects the way the body responds to opioids and alcohol. It can help decrease cravings and blocks euphoric or “high”-like feelings. This is why it is approved for use in people with opioid or alcohol addiction.4

At low doses, naltrexone has a different effect. It may play a role in changing pain signaling. However, its main effect is on the immune system. It decreases the action of several types of immune system cells that can cause damage in autoimmune conditions. LDN also may decrease inflammation in the nervous system and the body as a whole. These properties of LDN led doctors to ask if it could be used to treat conditions like multiple sclerosis (MS).1,2

A few small studies have looked at LDN with MS and other conditions, and results have been mixed. In these studies there has been no evidence that LDN affects the course of MS disease. In some studies, LDN reduced muscle spasticity, reduced fatigue, and improved quality of life. This shows LDN may have a role in symptom management. However, in other studies, these positive effects were not found. Overall, more research is needed to determine the true impact of LDN on MS, if any.1,2

What are the possible side effects of LDN?

At FDA-approved doses, naltrexone has several side effects. But at lower doses, LDN is well tolerated. Most people report few to no side effects at all. The most common issues that have arisen while taking LDN are:1-3

  • Sleep issues
  • Vivid dreams
  • Fatigue

Other potential side effects include:1-3

  • Nausea or vomiting
  • Abdominal pain
  • Changes in appetite

These are not all the possible side effects of LDN. Talk to your doctor about what to expect when taking the drug. You also should call your doctor if you have any changes that concern you when taking LDN.

Things to know about LDN

LDN is not a disease-modifying treatment (DMT) for MS. This is beause there is no evidence that it alters the course of MS disease It is not meant to replace other drugs used to slow MS progression. LDN is used with these options for additional benefit and symptom control. Do not make changes to your regular treatment plan without first talking to your doctor.1

Naltrexone can cause a person to experience withdrawal symptoms if they have a substance abuse issue. Talk with your doctor if you have struggled with substance abuse in the past or are currently dealing with opioid or alcohol use issues.4

Naltrexone can cause liver damage. However, this is typically at higher doses than used for MS. Tell your doctor if you have a history of liver issues before starting LDN. Also tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.1,2,4

Before beginning treatment for MS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information for naltrexone hydrochloride.

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