Acamprosate (Campral)

What Is Acamprosate Used For?

Acamprosate is a prescription medication used to help people who have stopped drinking alcohol maintain their abstinence, meaning staying alcohol-free. Its benefit is not universal, but a substantial body of research shows that it can improve the chances of staying alcohol-free when combined with counseling and recovery support^[1][2][3].

Emergency and Crisis Support

Thoughts of suicide or urges to hurt yourself call for immediate help. In the United States, call or text 988; call 911 in a life-threatening situation^[4].

Acamprosate does not prevent or relieve alcohol withdrawal. Suddenly stopping after prolonged heavy drinking can cause potentially life-threatening withdrawal, including seizures. Seek medical help to plan a safe recovery; alcohol detoxification care is a separate need from medication to help maintain abstinence.^[1][5]

The prescribing-information excerpts used below were revised in November 2022. Confirm current prescribing details with a clinician or pharmacist.^[1]

When Acamprosate Is Started and What It Does Not Treat

Acamprosate is indicated for people who have already stopped drinking. The label states it is for “the maintenance of abstinence from alcohol in patients with alcohol dependence who are abstinent at treatment initiation”^[1].

Treatment should be initiated as soon as possible after the period of alcohol withdrawal, once abstinence has been achieved^[1][6]. A meta-analysis confirmed that detoxification before medication administration was associated with better abstinence outcomes compared to placebo^[7].

Acamprosate has three important treatment limits:

• Acamprosate does not treat alcohol withdrawal. The label is explicit: “Use of acamprosate calcium does not eliminate or diminish withdrawal symptoms”^[1][6].
• Efficacy has not been demonstrated in people who have not undergone detoxification and achieved abstinence before starting treatment. Detoxification is the period in which withdrawal is managed after stopping alcohol^[1][6]. A fourth clinical study that enrolled patients who had not been required to be abstinent at baseline failed to show superiority over placebo^[1].
• Evidence is limited for disorders involving multiple substances. Effectiveness has not been adequately assessed in people with polysubstance use disorders—disorders involving more than one substance^[1][6].

How Soon Does Acamprosate Reach Steady Levels?

The prescribing information says acamprosate reaches steady-state blood levels within five days of dosing. This describes when blood concentrations stabilize with repeated doses; it does not establish that a person will notice a treatment benefit within five days.^[1]

What Taking Acamprosate Involves

The prescribing information describes a usual dose of two 333 mg delayed-release tablets taken three times daily, for a total of 1,998 mg per day. Delayed-release means the formulation releases the medication after a delay rather than immediately^[1].

Although the tablets can be taken without regard to meals, dosing with meals was used during clinical trials and is suggested for people who regularly eat three meals a day^[1].

The three-times-daily schedule and the size of the tablets can be challenging. The VA/DoD clinical practice guideline notes that this divided-dose regimen “presents a challenge to many patients and can negatively affect treatment adherence”^[8]. Discussing strategies for remembering doses with a clinician may be worthwhile.

What to Do After a Missed Acamprosate Dose

The Veterans Health Library’s patient guidance says that if a dose is missed, do not double the next dose⁠^[3]. Ask a clinician or pharmacist to clarify any other missed-dose questions for your prescription.

How Long Acamprosate Treatment May Continue

Most people take acamprosate for at least six months and often longer; discuss the appropriate duration with a clinician^[3]. Clinical trial durations ranged from 90 days to 360 days^[1].

What to Do If Drinking Resumes While Taking Acamprosate

A relapse does not mean acamprosate should be stopped. The label advises that treatment “should be maintained if the patient relapses” and that patients should “continue acamprosate calcium delayed-release tablets therapy as directed, even in the event of relapse” and discuss any renewed drinking with their clinician^[1]. The label reports that acamprosate does not affect alcohol pharmacokinetics and that alcohol does not affect acamprosate pharmacokinetics^[1].

How Kidney and Liver Function Affect Acamprosate Treatment

Acamprosate is not broken down by the liver. It leaves the body unchanged through the kidneys^[1]. This pattern of drug handling—part of its pharmacokinetics, meaning how the body absorbs, distributes, and clears a drug—has two practical consequences:

1. Mild to moderate liver impairment does not require a dose change. The body’s handling of acamprosate is unaltered in patients with mild to moderate liver impairment, classified as Child-Pugh groups A and B. Child-Pugh is a liver-disease severity classification^[1].

The VA/DoD guideline identifies two situations in which acamprosate may be considered: taking prescribed opioids and having significant liver damage or impairment. These are treatment-selection considerations; the guideline also notes that acamprosate does not rely on the liver for clearance^[8].

2. Kidney impairment is the key safety concern. Creatinine clearance is a measure of kidney filtering function, expressed in milliliters per minute (mL/min). After a single dose of two 333 mg delayed-release tablets, patients with moderate kidney impairment (creatinine clearance 30–50 mL/min) had peak plasma concentrations—the highest blood levels—about twice those of healthy subjects^[1].

Their half-life—the time needed for the drug level to fall by half—was about 1.8 times that in healthy subjects. The recommended dose for moderate kidney impairment is reduced to one 333 mg tablet three times daily^[1][6]. These are prescribing considerations for a clinician, not instructions to adjust your own dose.

Acamprosate is contraindicated, meaning it should not be used, in severe kidney impairment (creatinine clearance ≤30 mL/min), where blood concentrations rise approximately fourfold^[1][6]. Because older patients are more likely to have reduced kidney function, monitoring may be especially useful in older adults^[1].

Common Side Effects Reported With Acamprosate

The Cochrane review identified diarrhea as the only side effect reported significantly more often with acamprosate than with placebo (risk difference 0.11, 95% CI 0.09–0.13)^[2].

In the prescribing information’s pooled clinical trial data, diarrhea occurred in 17% of the label’s 1,998 mg/day group, which also included 258 patients receiving a different 2,000 mg/day regimen, compared with 10% of placebo-treated patients, and it was the only adverse event leading to discontinuation in more than 1% of patients (2% vs. 0.7%)^[1][6].

Other adverse events reported at a rate of 3% or greater and exceeding placebo in at least one dosage group included:^[1]

• Energy and appetite: Asthenia (weakness), pain, anorexia (loss of appetite), and flatulence (gas)
• Digestive symptoms: Nausea and dry mouth
• Mood and sleep: Anxiety, depression, and insomnia (difficulty sleeping)
• Other symptoms: Dizziness, paresthesia (tingling sensations), pruritus (itching), and sweating.

These were reported events, not necessarily proven drug effects.

Overall, 8% of acamprosate-treated patients discontinued due to adverse events in studies of six months or less, compared with 6% on placebo; in longer studies, the discontinuation rate was 7% in both groups^[1][6].

Can Acamprosate Affect Weight?

Weight gain and weight loss were reported during clinical evaluation. People taking acamprosate with antidepressants reported both more commonly than people taking either medicine alone. These reports do not establish that acamprosate caused every weight change.^[1]

Serious Acamprosate Warnings and When to Get Help

Discuss these warnings with the clinician prescribing acamprosate, and use the urgent-help instructions below when needed.

Depression and Suicide Risk During Acamprosate Treatment

In controlled clinical trials, adverse events of a suicidal nature (suicidal ideation, suicide attempts, and completed suicides) were infrequent overall but were more common in acamprosate-treated patients than in placebo-treated patients: 1.4% vs. 0.5% in studies of six months or less, and 2.4% vs. 0.8% in year-long studies^[1][6].

Completed suicides occurred in 3 of 2,272 (0.13%) acamprosate-treated patients and 2 of 1,962 (0.10%) placebo-treated patients across all controlled studies^[1][6].

Depression itself was reported at similar rates in both groups^[6]. The label notes that many of these events occurred in the context of alcohol relapse, and the relationship between alcohol dependence, depression, and suicidality is complex, with no consistent pattern identified^[1].

Patients, families, and caregivers should watch for emerging symptoms of depression or suicidal thinking and report them promptly to a healthcare provider⁠^[1][6].

Who Should Avoid Acamprosate Because of an Allergy?

Acamprosate should not be used by people who have previously had a hypersensitivity reaction to acamprosate or any of its components. Hypersensitivity means an allergic reaction. Tell the prescriber about a previous reaction before taking it.^[1]

Acamprosate and Allergic Reactions to Sulfites

Acamprosate tablets contain trace residual sodium sulfite from the manufacturing process. Sulfites can cause allergic-type reactions, including potentially severe asthmatic episodes, in susceptible individuals—particularly people with asthma^[1]. If someone is having a serious allergic reaction, call 911 in the United States^[9].

Reports of Acute Kidney Failure With Acamprosate

Post-marketing reports have described acute kidney failure temporally associated with acamprosate treatment in at least three patients^[1]. Because these reports come from voluntary post-marketing surveillance, a causal relationship has not been established, but the signal reinforces the importance of kidney function assessment.

Acamprosate Interactions With Other Medicines

Acamprosate does not undergo liver metabolism. The label reports no potential to increase the activity of CYP1A2 and CYP3A4, two cytochrome P450 (CYP) enzymes—proteins involved in breaking down medicines. Laboratory studies suggest it does not inhibit, or slow, metabolism mediated by CYP1A2, 2C9, 2C19, 2D6, 2E1, or 3A4^[1]. These findings concern the specified enzymes, not every enzyme in this family.

The body’s handling of acamprosate was unaffected when it was taken with alcohol, diazepam, or disulfiram. No clinically important interactions with naltrexone were observed, although taking them together increased acamprosate’s peak concentration by 33% and overall exposure—the body’s total exposure to the drug over time—by 25%. The label recommends no dose adjustment for this combination^[1].

In clinical trials, the safety profile in patients taking acamprosate alongside anxiety medicines, sleep medicines or sedatives (including benzodiazepines), or non-opioid pain relievers was similar to that of patients taking placebo with those same medications^[1].

What Clinicians Monitor During Acamprosate Treatment

Several aspects of acamprosate treatment benefit from ongoing clinical follow-up, and understanding their purpose can help patients get the most from appointments:

• Kidney function. The kidneys are the major route of acamprosate excretion, and severe renal impairment is a contraindication. Kidney function therefore informs dosing and whether the medication can be used. The label notes that older patients are more likely to have decreased renal function and that monitoring may be useful^[1].
• Mood and suicidality. Suicidal events were more common in acamprosate-treated patients than in placebo-treated patients in controlled trials, and the label advises monitoring for emerging depression or suicidal thinking^[1][6]. Follow-up visits provide a structured opportunity for this.
• Side effects and tolerability. Diarrhea is the adverse event most likely to lead to discontinuation^[1]. Discussing tolerability allows a clinician to weigh whether dose adjustment (for patients with moderate renal impairment) or other strategies are needed.
• Adherence. The three-times-daily dosing schedule can negatively affect adherence^[8]. Follow-up is a chance to identify and troubleshoot missed-dose patterns.
• Relapse. The label advises continuing acamprosate even after a relapse and discussing any renewed drinking with a clinician^[1]. Follow-up visits allow that conversation to happen promptly.
• Treatment duration. Most people take acamprosate for at least six months and often longer^[3]. Periodic reassessment helps a clinician and patient decide together when to continue, adjust, or stop treatment.

How Acamprosate Supports Alcohol Abstinence

Chronic alcohol exposure is thought to disrupt the balance between signals that activate brain cells (excitatory signaling) and those that restrain their activity (inhibitory signaling). Laboratory and animal studies suggest that acamprosate may help restore this balance by interacting with neurotransmitters—chemical messengers between nerve cells—including glutamate and gamma-aminobutyric acid (GABA). Its mechanism is not completely understood^[1].

Acamprosate does not produce alcohol aversion—a reaction intended to discourage drinking by making it unpleasant^[1]. In animal studies of drug effects, it showed no seizure-preventing (anticonvulsant), antidepressant, or anxiety-reducing (anxiolytic) activity^[1].

Animal studies found no development of tolerance or dependence. Clinical trials at therapeutic doses found no evidence of withdrawal symptoms, and reports collected after approval outside the United States provided no evidence of abuse or dependence^[1].

Acamprosate was first approved in the United States in 2004^[1]. The French Alcohol Society, in partnership with the European Federation of Addiction Societies, recommended acamprosate and naltrexone as first-line medications—initial medication options—for relapse prevention. Its grade A designation is a guideline recommendation rating^[10].

A meta-analysis combines results from multiple studies. One examined 64 randomized, placebo-controlled trials of acamprosate or naltrexone: participants were assigned by chance to a medication or an inactive comparison treatment called a placebo^[7].

Across these trials, acamprosate had a statistically larger effect size—the measured size of benefit—for maintaining abstinence, while naltrexone had a larger effect size for reducing heavy drinking and craving^[7]. This comparison of placebo-controlled trials does not predict which medicine will work better for one person. Acamprosate is best understood as support for ongoing abstinence rather than for reducing drinking.

These are comparisons across placebo-controlled trials, not a prediction of the better medicine for one person.^[7]

What Research Shows About Acamprosate’s Benefits

A 2010 Cochrane review pooled 24 randomized controlled trials involving 6,915 participants. Compared with placebo, acamprosate significantly reduced the risk of any drinking: relative risk (RR) 0.86, or a 14% lower relative risk. The 95% confidence interval (CI) was 0.81–0.91; this range describes uncertainty around the estimate. Acamprosate also significantly increased cumulative abstinence duration—the total time without drinking^[2].

The Cochrane review found no significant indication of publication bias—the possibility that which studies get published could skew the overall findings. Results from industry-sponsored trials (RR 0.88, 95% CI 0.80–0.97) did not significantly differ from those of non-profit-funded trials (RR 0.88, 95% CI 0.81–0.96); this does not establish that the two sets of results are equivalent^[2].

A separate systematic review—a structured review of research—found moderate-strength evidence that acamprosate reduced return to any drinking and the percentage of drinking days compared with placebo, but did not affect return to heavy drinking. “Moderate strength” describes confidence in the evidence, not the size of the benefit^[11].

Additional measures, called secondary outcomes, in the Cochrane review included heavy drinking and levels of gamma-glutamyltransferase, an enzyme measured in blood. These did not reach statistical significance: the data did not show a clear difference between acamprosate and placebo on those measures^[2]. The clearest evidence therefore supports reducing return to any drinking^[2][11].

The placebo response—improvement in the placebo group—varied considerably across trials. Larger placebo responses were associated with smaller measured medication benefits. In acamprosate trials, placebo responses also tended to be larger in studies published later^[12]. This pattern could make drug–placebo differences harder to detect and may help explain inconsistent results, but the association does not establish a cause.

The Department of Veterans Affairs/Department of Defense (VA/DoD) guideline notes that U.S.–European differences may reflect differences in detoxification setting, time abstinent before treatment, other medications taken at the same time, intensity of counseling and support, outcomes measured, and severity of participants’ alcohol use disorder^[8].

Which Patients Were Included in Acamprosate Research

The clinical trial evidence comes primarily from adults with alcohol dependence who had completed detoxification and achieved abstinence before starting medication^[1]. A sex-specific meta-analysis used individual patient data—records for each participant—from 22 studies across 18 countries, including 1,317 women and 4,794 men^[13].

That analysis found no differences between men and women on any measure of acamprosate effectiveness, safety, or tolerability—how well people could tolerate treatment. This does not prove identical effects. Women represented only 22% of participants in acamprosate randomized controlled trials, so the evidence base is weighted toward men^[13].

Very few older adults have been studied: only 41 of 4,234 patients in double-blind, placebo-controlled trials were 65 or older, and none were 75 or over, so there is insufficient data to draw conclusions about safety or effectiveness in geriatric patients specifically^[1]. Safety and efficacy have not been established in pediatric populations^[1].

Results have also varied geographically. European studies have generally shown positive drinking outcomes, whereas some U.S. trials have failed to show those benefits. European studies also showed reduced risk of stopping treatment for any reason, whereas trials conducted in the rest of the world showed increased risk of stopping treatment associated with acamprosate^[8].

Possible explanations include differences in detoxification setting, time abstinent before treatment, study treatment duration, other medications taken at the same time, type and intensity of counseling and support, outcomes measured, and severity of participants’ alcohol use disorder^[8].

Why Counseling and Recovery Support Matter With Acamprosate

Acamprosate is intended to be part of a comprehensive treatment program that includes counseling and psychosocial support. Clinical trials used it alongside psychosocial therapy, and the label describes benefit for maintaining abstinence in that context.^[1]

You can explore online therapy options or search the treatment centers directory. Ask prospective providers whether they offer medication assessment, counseling, and ongoing follow-up.

Why Acamprosate Research Cannot Predict One Person’s Outcome

Population-level trial results show a modest average benefit for maintaining abstinence, but cannot predict whether acamprosate will work for an individual. An NNT of about 9 means that, on average, treating about nine people with acamprosate rather than placebo produces one additional favorable abstinence outcome across the studies’ treatment periods^[2].

Kidney function, whether detoxification and abstinence have been achieved, other medicines taken at the same time, access to counseling and recovery support, and patient preferences all shape whether acamprosate is a good fit^[1][8].

Find Help With Acamprosate and Alcohol Recovery

Use these steps to prepare for treatment and follow-up with your care team:

• Talk with a clinician about whether acamprosate is appropriate given your medical history, kidney function, and treatment goals.
• Complete detoxification first. The evidence supports starting acamprosate after withdrawal has been managed and abstinence achieved.
• Plan for the dosing schedule. Three-times-daily dosing requires some organization; the label suggests taking doses with meals for people who regularly eat three meals daily^[1].
• Engage in counseling or a recovery support program. Acamprosate is indicated as part of a comprehensive program that includes psychosocial support^[1].
• Monitor mood. Let your clinician, family, or support network know if you notice new or worsening depression or thoughts of self-harm.
• Don’t stop if a relapse occurs. Discuss any return to drinking with your clinician, but continue taking the medication as directed.
• Keep follow-up appointments and ask whether renal-function assessment is needed, because kidney function affects dosing and whether acamprosate can be used^[1].