Skip to main content

Does naltrexone block endorphins?

Medically reviewed by Sally Chao, MD. Last updated on Jan 23, 2023.

Official answer


Naltrexone is a drug used to treat both alcohol use disorder and opioid use disorder. It binds to the body's endorphin receptors and blocks the effects of alcohol and opioid drugs. This type of drug is called an opioid receptor antagonist.

When someone drinks alcohol, it stimulates the brain to produce tiny molecules called endorphins. Endorphins are similar to the opioid drug morphine. Endorphins and opioids both bind to opioid receptors in the brain to cause the pleasurable feelings that people enjoy when they drink alcohol or use an opioid drug. The medical term for this feeling is euphoria.

When naltrexone is used to treat opioid abuse disorder, it directly blocks the effects of opioid drugs that use the same receptors as endorphins. Naltrexone blocks the opioid receptors in the brain by binding to them for an extended period of time. Alcohol does not directly bind to opioid receptors. In alcohol use disorder, naltrexone works indirectly by blocking endorphins. There will be no euphoria.

Naltrexone is approved for people aged 18 or older. It can be given as a daily pill or a long-acting injection. A 2016 review of studies in more than 9,000 patients with alcohol use disorder found that taking a daily naltrexone pill decreased heavy drinking and increased the ability to stop drinking (abstinence). Naltrexone also reduced alcohol cravings.

Naltrexone is started after a detox period when a person is no longer physically dependent on alcohol. If started while someone is still physically dependent, naltrexone may cause withdrawal symptoms like nausea and vomiting.

Naltrexone may be used for 3 to 4 months to help establish abstinence. As part of medication-assisted treatment, it is often used with other treatments like counseling and support. Naltrexone is not addictive, and it does not cause withdrawal symptoms. It is not a drug that can be abused.

  1. U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration. Naltrexone. September 15, 2020. Available at: [Accessed January 11, 2021].
  2. Winslow BT, Onysko M, Hebert M. Medications for alcohol use disorder. Am Fam Physician. 2016 Mar 15;93(6):457-65.
  3. National Institutes of Health, National Institute on Alcohol Abuse and Alcoholism. Neurobiology of alcohol dependence. Available at: [Accessed January 11, 2021].

Related medical questions

Drug information

Related support groups