Ray 2019: how naltrexone changes the way alcohol feels

What they tested

Researchers pooled human laboratory studies in which people took naltrexone or a placebo and then drank alcohol under controlled conditions. They looked at four kinds of subjective response, meaning how alcohol felt to the person: craving, stimulation, sedation and negative mood.

Each measure drew on a different set of studies, from 9 studies (281 people) for negative mood to 18 studies (777 people) for sedation.

What they found

Compared with placebo, naltrexone reduced craving (Hedges g = -0.252, from 16 studies with 686 people) and reduced stimulation (g = -0.223, from 15 studies with 675 people). Hedges g is a standard measure of effect size; a negative value means less of that feeling on naltrexone.

It increased sedation (g = 0.251, from 18 studies with 777 people) and negative mood (g = 0.227, from 9 studies with 281 people). All four effects were significant (P < 0.01) and held when usual drinks per month and the alcohol dose were added to the models.

Effects on craving and stimulation showed up both in heavy drinkers and in people with alcohol use disorder.

Limits

• These are short lab studies, so they show how alcohol feels in a session, not how much people drink over months.
• The effects were small, by the authors' own description.

What it means if you're considering naltrexone

This review backs the main theory of how naltrexone works for alcohol: it makes drinking a bit less rewarding and a bit more unpleasant. That's the idea behind taking it to cut down, but the lab effects were small, and the review can't say how they translate into drinking less day to day.