Acamprosate vs. Naltrexone – Which Medication Fits Whom?

Acamprosate or naltrexone? If you’re in early recovery and talking to a doctor about medication, this is likely the first choice you’ll face. Both are FDA-approved for alcohol use disorder, both are well studied, and both lower your risk of relapse. But they work on completely different systems in the brain. So the real question isn’t which one is “stronger.” It’s which one fits your goal and your drinking pattern.

That question matters more than most people realize. According to US survey data, fewer than one in a hundred people with alcohol use disorder receive any medication for it, even though effective options have been available for decades.

Two Medications, Two Different Targets in the Brain #

Years of heavy drinking change the brain on more than one level. The balance between excitatory and inhibitory brain chemicals gets thrown off. At the same time, your reward system learns that alcohol feels good. Acamprosate and naltrexone each go after one of these two problems.

Acamprosate: Calming an Overexcited Brain #

After withdrawal, your brain often stays revved up for weeks or months. Think of glutamate as the gas pedal and GABA as the brake. Through neuroadaptation, heavy drinking leaves the gas pedal pressed harder than the brake can handle. Acamprosate is meant to restore that balance.

For years, the explanation was that acamprosate dampens glutamate activity. Newer research, led by a team in Mannheim, Germany, suggests the calcium in the drug may play a major role. The honest answer is that nobody knows exactly how acamprosate works. What we do know is that it works continuously in the background, whether you drink or not.

Naltrexone: Taking the Reward Out of Drinking #

When you drink, your brain releases its own endorphins. They bind to opioid receptors and trigger a surge of dopamine, which produces that familiar warm glow. Naltrexone blocks those receptors. Alcohol loses part of its payoff. That matters most in the moment when one drink is about to turn into five. Naltrexone can weaken that chain reaction.

What the Research Says About Acamprosate vs. Naltrexone #

A 2013 meta-analysis of 64 clinical trials asked a practical question: when does each medication help most? The results line up with how the drugs work. Acamprosate was slightly better at helping people stay abstinent. Naltrexone was slightly better at reducing heavy drinking and craving. Acamprosate worked best when people had fully completed withdrawal before starting.

A major review published in JAMA in 2023 looked at 118 trials and named both drugs first-line treatments for alcohol use disorder. To keep one additional person from returning to any drinking, about 11 people needed to take acamprosate, or about 18 needed to take oral naltrexone. Only naltrexone measurably protected against a return to heavy drinking. The monthly injectable form of naltrexone reduced the number of drinking days but did not clearly prevent relapse. And in the few studies that compared the two pills head to head, neither came out clearly ahead.

There’s an important American footnote. In the large US COMBINE study from 2006, naltrexone helped, but acamprosate performed no better than a placebo. Researchers still debate why. Most of the trials showing a benefit for acamprosate were run in Europe and mainly included people whose goal was complete abstinence.

Which Medication Fits Which Person? #

The research gives you a rough guide, not a rulebook. If your goal is to stay completely sober after detox, the evidence leans toward acamprosate. If your biggest problem is losing control, where one drink quickly turns into many, the evidence leans toward naltrexone. Naltrexone may also help if you react strongly to triggers like certain places, smells, or situations.

You’ll often read that acamprosate also eases anxiety, restlessness, or post-acute withdrawal symptoms. That sounds plausible given how it’s thought to work. But there’s no solid clinical evidence for it.

	Acamprosate	Naltrexone
How it works	Stabilizes the brain after withdrawal (exact mechanism unclear)	Blocks opioid receptors and blunts alcohol’s reward
Best evidence for	Staying abstinent	Reducing heavy drinking and craving
When to start	After detox is complete	After detox, works better after a period of abstinence
How it’s taken	Pills several times a day	Pill once a day, or a monthly injection
Cleared by	Kidneys, unchanged	Liver
Key reasons not to use it	Kidney impairment, breastfeeding, severe liver failure	Acute hepatitis, liver failure, current opioid use
Most common side effects	Diarrhea	Nausea, headache, dizziness, fatigue
Opioid painkillers	No interaction	Blocked

Starting Treatment: Timing and Dosing Schedule #

Neither medication treats acute withdrawal symptoms. Both are meant for the weeks and months after detox. Acamprosate is usually started as soon as possible after withdrawal and taken several times a day, typically for about a year. Oral naltrexone is taken once a day. Extended-release naltrexone, sold as Vivitrol, is a monthly injection given by a health care provider.

Before you start naltrexone, you need to be opioid-free, usually for at least 7 to 10 days. That includes prescription painkillers and some cough medicines. Otherwise, naltrexone can throw you into sudden opioid withdrawal. Be upfront with your doctor about everything you take.

With either drug, a slip is not a reason to stop treatment. That moment is exactly when naltrexone can do its best work. Some doctors prescribe naltrexone to be taken only before planned drinking situations, an approach often called the Sinclair Method. That use is off-label in the US. Nalmefene, a related drug approved in Europe for cutting back on drinking, is not FDA-approved for alcohol use disorder.

Side Effects and Safety: Liver, Kidneys, and Painkillers #

Both medications are generally well tolerated, and neither is addictive. The biggest difference is how your body clears them. Acamprosate isn’t processed by the liver, so it can be an option for many people with alcohol-related liver damage. It’s not approved for severe liver failure, though. Because your kidneys clear it, you can’t take it if your kidney function is impaired. Diarrhea is the most common side effect.

Naltrexone is processed by the liver. It’s not appropriate if you have acute hepatitis or liver failure, and your doctor will likely check your liver enzymes. Common side effects include nausea, headache, dizziness, fatigue, and trouble sleeping. These often fade within the first few weeks.

One practical point is easy to miss. Naltrexone also blocks opioid painkillers. If you need surgery, dental work, or emergency care, the people treating you have to know you’re on it. A wallet card or medical ID bracelet is a smart idea, especially with the monthly injection, which keeps working for weeks.

Can You Take Acamprosate and Naltrexone Together? #

On paper, it makes sense: one drug calms the brain, the other takes away the reward. The research is mixed. A German study of 160 patients published in 2003 found the lowest relapse rate with the combination. It beat placebo and acamprosate alone, but not naltrexone alone. In the much larger COMBINE study, adding acamprosate to naltrexone brought no extra benefit. The combination is considered safe. But it isn’t standard, and it’s a decision for you and your doctor to make case by case.

What This Means for Your Recovery #

Acamprosate and naltrexone aren’t competitors. They’re tools for different jobs. Neither one will do the work of recovery for you. But either can meaningfully improve your odds, especially alongside counseling, therapy, or a support group. The right choice depends on your goal, your drinking pattern, your liver and kidney health, and whatever else you take. Talk it through with a doctor who has experience in addiction medicine. Disulfiram is a third FDA-approved option, and several other medications are used off-label.

Medication is one building block, not the whole house. Many people in our community have tried acamprosate or naltrexone. Ask them about their experience in the Bye Bye Booze community.

Frequently Asked Questions About Acamprosate and Naltrexone #

Sources #

• Maisel NC et al. (2013): “Meta-analysis of naltrexone and acamprosate for treating alcohol use disorders: when are these medications most helpful?” Addiction, 108(2).
• McPheeters M et al. (2023): “Pharmacotherapy for Alcohol Use Disorder: A Systematic Review and Meta-Analysis.” JAMA, 330(17).
• Anton RF et al. (2006): “Combined pharmacotherapies and behavioral interventions for alcohol dependence: the COMBINE study: a randomized controlled trial.” JAMA, 295(17).
• Kiefer F et al. (2003): “Comparing and combining naltrexone and acamprosate in relapse prevention of alcoholism: a double-blind, placebo-controlled study.” Archives of General Psychiatry, 60(1).
• Spanagel R et al. (2014): “Acamprosate produces its anti-relapse effects via calcium.” Neuropsychopharmacology, 39(4).

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