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Article: Naltrexone

Naltrexone - HealthBrew Clinic
weight loss


Naltrexone was initially approved by the FDA for the treatment of opioid dependence in 1984 and later for alcohol dependence in 1994. Low-dose naltrexone (LDN), typically between 1.5 mg and 4.5 mg, has gained attention for its various off-label uses, including autoimmune conditions, chronic pain, and potential weight loss benefits.

Mechanism of Action

FDA-Approved Uses: Naltrexone works by acting as an opioid antagonist, which blocks opioid receptors and thereby decreases cravings for alcohol and opioids.

Off-label for Weight Loss: At lower doses, the exact mechanisms are not well-understood. However, it's thought that naltrexone might modulate the immune system and could potentially alter gut microbiota or exert central effects on appetite regulation.

FDA Indications

  • Opioid dependence
  • Alcohol dependence

Off-Label Indications

  • Autoimmune conditions
  • Chronic pain
  • Weight loss (preliminary evidence, often in combination with other medications like bupropion)

Clinical Evidence

Studies specific to the effect of low-dose naltrexone on weight loss are limited. However, there is evidence suggesting that it could improve insulin sensitivity. Most existing research examines naltrexone in combination with bupropion for weight loss benefits.

Side Effects

  • Standard Dose (50-300mg): Nausea, headache, dizziness, insomnia, and rare cases of hepatotoxicity.
  • Low Dose (1.5-4.5mg): Less frequent side effects but may include sleep disturbances or vivid dreams.

Drug Interactions

  • Opioids
  • Alcohol
  • Certain antibiotics, specifically rifampin


  • Acute hepatitis or liver failure
  • Current opioid use
  • Pregnancy (insufficient data for low doses)

Liver Function Tests

Liver function tests may not be as frequently required for low-dose naltrexone compared to standard doses. However, this is subject to clinical judgment based on individual patient characteristics.

Warnings and Precautions

While the risk is generally lower with low-dose naltrexone, it's important to avoid opioid use and to watch for signs of liver dysfunction, although this is less common with low doses.

Adverse Reactions

The most common adverse reactions are gastrointestinal in nature, such as nausea and vomiting, although these are less likely with low doses.

Use in Specific Populations

The use of low-dose naltrexone in special populations like pregnant or lactating women, and individuals with severe liver or kidney disease is not well-established due to a lack of studies.


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