Low-Dose Naltrexone Alcohol Interaction: What the Evidence Actually Shows

What does the naltrexone tablet label say about alcohol?

The clinical pharmacology section of the current generic naltrexone tablet label states that naltrexone 'is not aversive therapy and does not cause a disulfiram-like reaction either as a result of opiate use or ethanol ingestion' [1]. The same section says naltrexone has been shown to reduce alcohol consumption in clinical studies [1].

Alcohol does not appear in the label's contraindications list. That list covers patients receiving opioid analgesics, patients currently dependent on opioids including those maintained on methadone or buprenorphine, patients in acute opioid withdrawal, anyone who failed a naloxone challenge test or has a positive urine screen for opioids, and anyone with a history of sensitivity to naltrexone or the product's components [1].

The drug interactions section covers opioid-containing medicines, disulfiram and thioridazine [1]. For disulfiram, the label says safety and efficacy of combined use are unknown and that using two potentially hepatotoxic medicines together is not ordinarily recommended unless the probable benefits outweigh the known risks. For thioridazine, lethargy and somnolence have been reported [1]. The label also says studies of interactions between naltrexone and drugs other than opioids have not been performed, so caution is advised with any concomitant drug [1].

Is naltrexone approved for alcohol dependence?

Yes, at full doses. Oral naltrexone 50 mg is FDA-approved for alcohol dependence [1]. The regimen studied in the placebo-controlled trials was 50 mg once daily for up to 12 weeks, and other doses or durations were not evaluated in those trials [1]. Vivitrol 380 mg monthly is approved for alcohol dependence in patients who are able to abstain from alcohol in an outpatient setting before starting [2]. LDN is not an approved treatment for alcohol dependence [3].

A 2014 meta-analysis of 122 randomized trials (22,803 participants, with naltrexone studied in 53 trials and 9,140 people) calculated that oral naltrexone 50 mg a day had a number needed to treat of 20 to prevent return to any drinking and 12 to prevent return to heavy drinking [4].

The COMBINE trial randomized 1,383 recently abstinent adults with alcohol dependence. Naltrexone 100 mg a day plus medical management produced 80.6% days abstinent versus 75.1% with placebo plus medical management, and naltrexone reduced the risk of a heavy drinking day (hazard ratio 0.72, 97.5% CI 0.53 to 0.98, P=0.02) [5]. The dose in that trial was twice the labeled 50 mg.

These results describe full-dose naltrexone. They do not describe what a 4.5 mg compounded capsule does.

Does low-dose naltrexone change the picture?

LDN is not an FDA-approved product or indication. It means naltrexone at doses far below the 50 mg tablet, typically 0.5 to 6 mg a day and most often 4.5 mg, used off-label and supplied mainly through compounding pharmacies [3]. The FDA states that compounded drugs are not FDA-approved and that it does not verify their safety, effectiveness or quality before they are marketed [6].

A 2026 narrative review screened 105 studies, including 15 randomized trials, and concluded that current evidence does not support routine clinical use of LDN. It described LDN as low-risk but unproven, with early positive findings rarely confirmed in placebo-controlled trials [3]. The same review notes that safety data in pregnancy and in liver or kidney impairment are sparse, and that inconsistencies in compounded formulations add uncertainty [3].

The approved labels were written for 50 mg tablets and 380 mg injections and give no guidance on LDN doses. The contraindication for people receiving opioid analgesics is written without any dose exception [1][2]. Applying the disulfiram statement or the liver warning to a 4.5 mg capsule would be an extrapolation from higher-dose data.

Does timing matter around alcohol and opioids?

For Vivitrol, the label says patients should not be actively drinking at the time of the first injection [2]. In the pivotal alcohol trial, the benefit was not evident in the 92% of participants who were actively drinking at the start [2].

The tablet label's timing instructions concern opioids: a minimum of 7 to 10 opioid-free days before starting, and vulnerability to precipitated withdrawal for as long as 2 weeks when switching from buprenorphine or methadone [1]. That interval is about precipitated withdrawal, not drinking.

What about the liver?

Hepatotoxicity is in the Warnings section of the labels. The current generic tablet label and the current Vivitrol label have no boxed warning [1][2]. Cases of hepatitis and clinically significant liver dysfunction occurred during development and after marketing, and transient asymptomatic transaminase elevations were seen in trials [1]. Placebo-controlled studies using up to 300 mg a day, five times the recommended dose, showed that naltrexone causes hepatocellular injury in a substantial proportion of patients, and the label links this to dose [1]. The Vivitrol label says to discontinue in the event of symptoms or signs of acute hepatitis [2].

In short-term controlled alcohol-dependence trials, the Vivitrol label reports AST elevations in 1.5% of people on Vivitrol and 1.5% on oral naltrexone versus 0.9% on placebo [2]. When patients had elevated transaminases, the tablet label notes that other possible causes were often identified, including pre-existing alcoholic liver disease [1].

What side effects do naltrexone and LDN cause?

For oral naltrexone 50 mg, an open-label safety study of about 570 people with alcoholism reported new-onset nausea in 10%, headache in 7%, dizziness in 4%, nervousness in 4%, fatigue in 4%, insomnia in 3%, vomiting in 3%, anxiety in 2% and somnolence in 2% [1]. For Vivitrol 380 mg in alcohol dependence, nausea occurred in 33% versus 11% on placebo, dizziness or syncope in 13% versus 4%, and any injection site reaction in 69% versus 50% [2].

LDN trials report mostly mild, transient effects, most often insomnia, vivid dreams, nausea and dizziness [3]. A meta-analysis of 4 randomized trials in fibromyalgia (222 patients) found more vivid dreams and nausea with LDN than placebo, with no significant difference in serious adverse events [7].