Naltrexone is one of the most commonly used medications to handle addictions of different sorts. More often than not, we hear about naltrexone being used for alcohol and opioid addiction, which are internal factors that cause dependency.
However, will it actually work for external causes of dependency, like gambling, or is it just a placebo in that scenario?
The good news is that it works and that’s backed by science. If you’d like to know how, you’re in the right place.
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How Does Naltrexone Work?
Naltrexone is an opioid antagonist. That means it binds to opioid receptors in the brain and blocks them, preventing the usual rush of pleasure those receptors produce when triggered.
It doesn’t sedate you. It doesn’t create dependency. It simply sits at the receptor site and stops the reward signal from firing the way it normally would.
The FDA approved naltrexone first for opioid addiction in 1984, then for alcohol dependence in 1994. In both cases, the mechanism is the same: take away the neurological payoff, and the compulsive behavior loses a lot of its pull.
That approval history matters because it establishes something important. Naltrexone isn’t experimental in the broad sense.
Decades of clinical trials have confirmed how it works at the biological level. The question for gambling isn’t whether the drug works; it’s whether the same brain circuitry is involved.
As it turns out, it is. That’s where things get interesting.
So, How Does Naltrexone Work in Addiction?
Addiction, at its core, is a reward loop gone wrong. A substance or behavior triggers the brain’s opioid receptors, dopamine floods the system, and the brain registers that experience as something worth repeating. Over time, that signal overrides rational decision-making entirely.
Naltrexone interrupts that loop at the receptor level.
For opioid addiction, the effects of naltrexone are straightforward. Opioid drugs bind to the same receptors that naltrexone occupies. When those receptors are already blocked, the drug produces no euphoria, no relief, no payoff. This receptor blockade effectively eliminates the reinforcing effect that drives continued opioid use.
Alcohol dependence works through a slightly different but related mechanism. Alcohol stimulates endorphin release, which then activates opioid receptors. Naltrexone blunts that downstream effect. A landmark trial found that naltrexone cut relapse rates in alcohol-dependent patients nearly in half compared to placebo.
In both cases, the drug doesn’t eliminate the urge entirely. What it does is strip the reward from the behavior, and without the reward, the compulsion gradually weakens.
That principle carries directly into how clinicians now think about gambling disorder.
The Brain Chemistry: Why Gambling Hooks Us
Most people assume gambling addiction is a willpower problem. It isn’t. It’s a neuroscience problem.
Every gambling event, a card flip, a spin, a sports bet settling, produces a spike in opioid-mediated dopamine activity. The American Psychiatric Association formally classified gambling disorder as an addictive disorder in the DSM-5, placing it alongside substance use disorders precisely because the underlying brain activity is similar.
What makes gambling particularly powerful is the unpredictability. Research shows that variable reward schedules, where the reward comes unpredictably rather than consistently, produce stronger dopamine responses than guaranteed rewards. Slot machines aren’t designed randomly. They’re designed to maximize that effect.
Impulse control breaks down under this kind of repeated neurological reinforcement. The brain starts prioritizing the next gambling opportunity the same way it would prioritize food or safety. That’s not a metaphor. That’s measurable circuitry.
This is also why standard approaches like willpower or simple abstinence pledges have limited reach on their own. The brain has been rewired at a structural level. Addressing that requires something that works at the same level.
That’s exactly what naltrexone does.
How Naltrexone Breaks the Circuit
Naltrexone doesn’t cure gambling disorder. It, however, reduces the neurological reward that sustains it.
When opioid receptors are blocked, the dopamine spike that follows a win or a near-miss is significantly dampened.
The gamble still occurs, but the brain doesn’t register it with the same intensity. Over time, that reduced signal weakens the compulsive pull. Research describes this mechanism as directly applicable to behavioral addictions, not just substance-related ones.
Let’s look a bit more clinically.
The clinical evidence for the treatment of pathological gambling with naltrexone is more substantial than most people realize.
The double-blind naltrexone trial by Kim et al., published in the Journal of Clinical Psychiatry, found that 75% of naltrexone-treated patients showed meaningful improvement in gambling urges over 11 weeks, compared to 24% in the placebo group.
A follow-up multi-site placebo-controlled study published in the National Library of Medicine reinforced those findings across a larger sample. Patients on naltrexone reported fewer gambling urges, less time gambling, and lower overall impulsivity scores compared to the placebo group.
It doesn’t stop there.
Naltrexone also shows a stronger treatment response in patients with a family history of alcohol dependence or those who report intense gambling urges at baseline. That suggests the drug works best when the opioid reward pathway is particularly active, which makes biological sense.
However, it isn’t a standalone fix. Most clinicians pair it with cognitive behavioral therapy, since CBT addresses the thought patterns and triggers that pharmacotherapy alone can’t reach. Together, the combination targets both the neurology and the behavior.
Dosing & Safety
The standard naltrexone dose for gambling disorder mirrors what’s used in alcohol and opioid treatment: 50mg once daily. Some clinical studies have tested higher doses, up to 150mg or 200mg daily, and found stronger reductions in gambling urges at those levels, though with a corresponding increase in side effects.
Naltrexone comes in two forms. The daily oral tablet is the most common. An extended-release injectable version, administered once monthly, exists primarily for patients where daily pill adherence is a concern.
One hard requirement before starting: the patient must be fully opioid-free for at least 7 to 10 days. Naltrexone will trigger immediate and severe withdrawal in anyone with active opioids in their system. This isn’t a precaution to take lightly.
Liver function is the other key safety consideration. Naltrexone is processed by the liver, and at higher doses, it can elevate liver enzymes.
Baseline liver testing before starting, and periodic monitoring during treatment, is standard healthcare practice. Patients with active hepatitis or significant liver disease are generally not candidates.
There’s no physical dependency risk. Stopping naltrexone doesn’t produce withdrawal. That’s a meaningful distinction from many other medications used in psychiatry and addiction treatment.
Side Effects & Limitations
The most common side effects of naltrexone are gastrointestinal: nausea, vomiting, stomach cramping, and reduced appetite. These tend to be most pronounced in the first one to two weeks and often subside as the body adjusts. Starting at a lower dose and titrating up can reduce their severity.
Other reported side effects include headache, fatigue, sleep disturbances, and anxiety. These are less consistent across patients but worth monitoring, particularly in anyone who is comorbid for depression or other mental health conditions.
Who Doesn’t Respond Well?
Naltrexone is not effective for everyone. Patients without a strong opioid-driven reward response to gambling may see limited benefit.
It also does nothing for the psychological triggers, the stress, the escape-seeking, the distorted thinking around odds and control. That’s the territory of cognitive behavioral therapy and psychotherapy, not pharmacotherapy.
What Are the Gaps in the Research?
It’s worth being clear about what the research base actually is. The clinical trials on naltrexone for gambling disorder are promising, but the sample sizes are smaller than those behind its alcohol and opioid approvals.
The Food and Drug Administration has not approved naltrexone specifically for gambling disorder. Clinicians prescribing it for this purpose are doing so off-label, based on the available evidence.
Nalmefene, a related opioid antagonist, has shown similar results in some studies and is worth discussing with a prescribing physician as an alternative pharmacological treatment option.
How Long Island Treatment Center Can Help
Naltrexone is a tool, not a complete plan. Getting the most out of it requires clinical oversight, proper dosing, and the kind of structured support that pairs medication with real behavioral work.
That’s what we do at Long Island Treatment Center in Hicksville, NY. We’re JCAHO-accredited and OASAS certified, and we offer multiple levels of outpatient care, including Intensive Outpatient and Partial Hospitalization programs.
Our approach combines medication-assisted treatment with cognitive behavioral therapy, individual counseling, and family therapy, all under one roof.
We also treat problem gambling directly, alongside substance addiction. That’s not a common combination, and it means you’re working with clinicians who actually understand gambling disorder rather than treating it as an afterthought.
If you or someone you love is struggling, call us today. The conversation is confidential, and we’re here when you’re ready.