Naltrexone for addiction treatment

Naltrexone binds to opioid receptors in the brain without activating them. By occupying those receptors, it prevents opioid drugs from producing their usual euphoric effects.

Its role differs slightly depending on the substance involved.

This blocking effect is why taking opioids while naltrexone is active can be dangerous. Attempting to overcome the blockade with higher doses of opioids can increase the risk of overdose.

A person generally needs to be opioid-free before starting naltrexone. Beginning treatment while opioid medication or other opioids are still in the body can cause sudden precipitated withdrawal.

The opioid-free period varies according to the substance used, dose, duration of use, and individual medical circumstances. A commonly cited interval is about 7 to 10 days after shorter-acting opioids, but longer periods may be necessary after methadone, buprenorphine, or other long-acting opioids.

A healthcare provider may review.

• Recent opioid use. This includes heroin, fentanyl, codeine, morphine, oxycodone, hydrocodone, methadone, and other opioid drugs.
• Withdrawal symptoms. Active opioid withdrawal generally needs to resolve before starting naltrexone.
• Current medications. Prescription, over-the-counter, and other drugs should be reviewed.
• Liver health. Liver function tests may be appropriate before or during treatment.
• Kidney disease or other medical conditions. These may affect medication decisions.
• Uncertainty about opioid exposure. In some clinical situations, a naloxone challenge test or other assessment may be considered before starting naltrexone.

Take naltrexone according to the prescription label and instructions from the prescribing healthcare provider.

Naltrexone may also be prescribed to treat alcohol use disorder. It does not create an unpleasant alcohol reaction in the way disulfiram does. Instead, it influences opioid-receptor pathways involved in alcohol reward.

For some people, naltrexone may help.

• Reduce alcohol cravings
• Reduce heavy drinking
• Decrease the rewarding effects associated with drinking alcohol
• Support treatment goals alongside counseling or behavioral care

Naltrexone does not prevent impairment from alcohol. Drinking alcohol can still affect coordination, judgment, reaction time, and health even when some of its rewarding effects are reduced.

It also does not prevent potentially dangerous alcohol withdrawal. Someone with physical dependence on alcohol may require medical assessment before stopping alcohol use.

The most important drug interaction involves opioids.

While taking naltrexone, opioid painkillers may not provide their expected effects because naltrexone blocks opioid receptors. This can complicate pain treatment after an injury, dental procedure, or surgery.

A doctor or other healthcare provider should know about naltrexone use before prescribing medications for pain.

Opioids that may be affected include:

• Codeine
• Morphine
• Oxycodone
• Hydrocodone
• Fentanyl
• Methadone
• Other opioid medications

People should not take higher doses of opioids in an attempt to overcome the blocking effect. Doing so can substantially increase overdose risk.

People should also review other prescription medications, supplements, and over-the-counter products with a healthcare provider before beginning treatment.

Naltrexone can lower opioid tolerance during treatment because the body is no longer regularly exposed to opioid effects.

After naltrexone wears off or treatment stops, returning to a dose of opioids that was previously tolerated can result in overdose.

Risk may be especially high when.

• Returning to opioid use after a period of abstinence
• Taking the same doses of opioids used before treatment
• Attempting to overcome naltrexone with higher doses
• Using fentanyl or other potent opioids
• Combining opioids with other drugs that suppress breathing

Stopping naltrexone does not immediately restore previous opioid tolerance. Any decision to stop taking naltrexone should be discussed with the prescribing professional.

Naltrexone is available in oral and extended-release injectable forms.

The daily pill may offer flexibility and may be easier to stop or adjust if side effects occur. The monthly injection provides sustained medication exposure without requiring a daily tablet.

The appropriate form depends on the condition being treated, adherence needs, medical considerations, access, and insurance coverage.

Instructions for a missed dose depend on which formulation is being used.

For the daily pill, the prescription label or prescribing healthcare provider should guide what to do after a missed dose. Do not take extra medication to make up for a missed dose unless specifically instructed.

For the monthly injection, a missed appointment may leave a period when the medication’s blocking effect is reduced. The prescribing professional can determine when to give the next dose.

Because opioid tolerance may be reduced during naltrexone treatment, returning to opioid use after a missed dose or discontinued treatment can carry an increased risk of overdose.

Research supports naltrexone as an evidence-based medication for both alcohol use disorder and opioid use disorder, but results vary.

For alcohol use disorder, naltrexone may reduce cravings, heavy-drinking days, and the rewarding effects of alcohol for some people.

For opioid use disorder, naltrexone can block the effects of opioids when medication coverage is maintained. Unlike methadone or buprenorphine, however, naltrexone requires a person to complete opioid withdrawal before starting treatment.

Medication alone also does not address every factor associated with substance use. Counseling, behavioral therapies, mental health care, support group meetings, relationships, housing, stress, and other circumstances can all affect long-term recovery.

Naltrexone may require ongoing medical review, particularly when there are concerns about liver health, other medications, or changes in substance use.

A care team or prescribing professional may monitor for the following symptoms.

• Persistent nausea or loss of appetite
• Dark urine
• Yellowing of the skin or eyes
• Ongoing abdominal pain
• Severe fatigue
• New or worsening mood symptoms

These symptoms may require evaluation for liver damage or another medical problem. People with severe liver disease may not be appropriate candidates for naltrexone, while others may need periodic liver function tests during treatment.

Medication decisions may also change over time. Lower doses, a different formulation, or another medication may be considered depending on side effects, treatment response, and medical history.

People taking naltrexone should avoid opioid drugs unless they are being managed specifically by a healthcare professional who knows about the medication.

Starting naltrexone while opioids are still in the body can trigger precipitated withdrawal. A person is commonly expected to remain opioid-free for a period before beginning treatment, although the exact interval depends on the opioid involved and individual circumstances.

There is also an important overdose concern after naltrexone treatment. Because opioid tolerance can decrease during treatment, returning to a previously tolerated dose after stopping naltrexone may carry a higher risk of overdose. Trying to overcome the medication’s blocking effect by taking larger doses of opioids is also dangerous and can lead to severe or fatal overdose.