How Quickly Does Naltrexone Work

Naltrexone is approved for use in the treatment of opioid use disorder and alcohol use disorder. Oral naltrexone is well-absorbed and will usually begin working within one hour after a dose. Intramuscular naltrexone is an extended-release formulation and has two peaks, first at 2 hours then again 2 to 3 days later.

Does naltrexone start working right away?

Naltrexone will begin working shortly after taking one dose.

Should I take naltrexone in the morning or at night for weight loss?

Naltrexone is usually taken at night and may provide additional benefits that help with weight loss. It has been shown that for patients with chronic pain, naltrexone can improve sleep.