The story everyone knows: semaglutide helps people lose weight. The story that's emerging is more interesting. The same class of peptides that suppress appetite appears to suppress the desire to drink, smoke, and use drugs. What began as patient anecdotes has become a legitimate area of clinical investigation, with pharmaceutical companies, academic researchers, and the National Institutes of Health all racing to understand how a gut hormone could rewire the brain's relationship with addiction.
This is the story of how incretin peptides went from metabolic medicine to the frontlines of addiction treatment, and what it means for the future of peptide therapeutics.
The Accidental Discovery
The first signals came from patients themselves. People prescribed semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound) for diabetes or obesity started reporting an unexpected side effect: they didn't want to drink anymore. Not through willpower. Not through aversion. The craving simply faded.
Online forums filled with these reports. A Reddit thread about Ozempic and alcohol went viral. Physicians began hearing it in clinic. By 2023, researchers had a name for the phenomenon and the preclinical data to explain it. By 2025, clinical trials were producing results.
The accidental nature of this discovery follows a familiar pattern in pharmacology. Sildenafil was developed for angina before becoming Viagra. Minoxidil was a blood pressure drug before it grew hair. The most transformative applications of a molecule are sometimes not the ones its creators intended.
The Biology: Why Gut Hormones Affect the Brain
GLP-1 (glucagon-like peptide-1) is an incretin hormone released by L-cells in the small intestine after eating. Its primary role is to stimulate glucose-dependent insulin secretion, slow gastric emptying, and signal satiety to the brain. GIP (glucose-dependent insulinotropic polypeptide) has overlapping but distinct effects, primarily in the pancreas and adipose tissue.
What makes these hormones relevant to addiction is where their receptors live. GLP-1 receptors are expressed throughout the central nervous system, with particularly high density in the ventral tegmental area (VTA), nucleus accumbens, amygdala, and hippocampus. These structures collectively form the mesolimbic dopamine pathway, the brain's reward circuit.
This is the same system that alcohol, nicotine, opioids, cocaine, and methamphetamine hijack to produce their reinforcing effects. Each of these substances, through different molecular mechanisms, ultimately increases dopamine release in the nucleus accumbens. That dopamine signal is what the brain interprets as "do that again."
GLP-1 receptor activation in these regions appears to modulate this process. Preclinical studies in rodents have demonstrated that GLP-1 agonists reduce dopamine release in the nucleus accumbens in response to alcohol, decrease voluntary alcohol consumption, attenuate nicotine self-administration, reduce heroin and fentanyl seeking, and decrease cocaine reinforcement. The drugs don't make consumption aversive; they appear to make it less rewarding, reducing the motivational pull of the substance.
Alcohol: The Most Advanced Data
Alcohol use disorder (AUD) is the addiction indication with the most clinical evidence for GLP-1 agonists.
A February 2025 study published in JAMA Psychiatry randomized 48 adults with AUD to receive either low-dose semaglutide or placebo for nine weeks. The semaglutide group consumed significantly less alcohol during a controlled laboratory self-administration task, with medium-to-large effect sizes. They also showed reduced drinks per drinking day and lower weekly craving scores throughout the treatment period.
The finding that stood out: these participants were not trying to quit drinking. They were non-treatment-seeking. The reductions in consumption appeared to be a direct pharmacological effect of the peptide acting on reward circuitry, not a result of behavioral intention.
Larger observational studies support the pattern. Analysis across 136 US healthcare systems found that patients with AUD who received GLP-1 agonists for metabolic conditions had a 36% lower rate of alcohol intoxication events compared to matched controls (HR 0.64, 95% CI 0.59-0.69). Subgroup analysis of different GLP-1 agonists suggested that tirzepatide, the dual GIP/GLP-1 agonist, showed the largest effect on alcohol-related outcomes, hinting that dual receptor engagement may confer additional benefit.
The pipeline is now robust. At least 15 registered clinical trials are studying GLP-1 receptor agonists for AUD. Semaglutide is the most studied (seven trials), followed by tirzepatide (four trials) and exenatide (two trials). Eli Lilly has committed to two Phase 3 trials of brenipatide, a next-generation GIP/GLP-1 agonist, enrolling 2,200 participants with moderate-to-severe AUD. The VA health system has launched the CRAVE study, a large Phase 3 trial of semaglutide 2.4 mg in veterans.
Nicotine: Dual-Purpose Treatment
The nicotine data is earlier-stage but consistent with the alcohol findings. Preclinical studies show that GLP-1 agonists reduce nicotine self-administration, reinstatement of nicotine-seeking, and other nicotine-related behaviors in rodents.
Early clinical signals are positive. In the semaglutide AUD trial, a subgroup of participants who smoked cigarettes showed greater reductions in cigarettes per day compared to placebo, an effect that reached statistical significance despite the small sample size.
The overlap matters clinically because AUD and nicotine dependence frequently co-occur. A medication that addresses both simultaneously would be genuinely novel. Current smoking cessation drugs (varenicline, bupropion, nicotine replacement) have no effect on alcohol consumption, and AUD medications have no effect on smoking. A GLP-1 agonist that reduces both could simplify treatment for the millions who struggle with both substances.
Eli Lilly has already registered a trial of brenipatide in 222 participants who recently quit smoking, testing whether the drug helps maintain abstinence and prevent post-cessation weight gain, a major barrier to sustained quitting.
Opioids and Stimulants: The Preclinical Frontier
The data for opioid and stimulant use disorders is almost entirely preclinical, but it follows the same biological logic.
In rodent models, GLP-1 receptor agonists reduce self-administration of heroin, fentanyl, and oxycodone. They also reduce reinstatement of drug-seeking behavior, which is the animal model equivalent of relapse. Given that the opioid crisis continues to claim over 80,000 American lives per year, even modest efficacy in this area would represent a meaningful addition to the treatment landscape.
For cocaine and methamphetamine, where no FDA-approved pharmacotherapies exist at all, the preclinical evidence has spurred the first human trials. Baseline Therapeutics, a startup that launched in January 2026, has announced plans for Phase 2/3 development of its GLP-1 agonist BT-001 for cocaine and methamphetamine use disorders beginning in the third quarter of 2026.
Exenatide (the oldest GLP-1 agonist) is the most studied compound for cocaine use disorder in clinical settings, with several registered trials. A study at Vanderbilt University is examining whether exenatide reduces cocaine self-administration in a controlled laboratory setting.
The Treatment Gap
To understand why this research matters, consider the scale of unmet need.
Alcohol use disorder affects 29 million Americans. Only three medications are FDA-approved (naltrexone, acamprosate, disulfiram), all developed decades ago. Naltrexone, the most prescribed, has a number needed to treat of 12 to prevent return to heavy drinking. Fewer than 10% of people with AUD receive medication treatment. No new FDA-approved AUD medication has arrived in nearly two decades.
Opioid use disorder affects approximately 6 million Americans. Effective medications exist (methadone, buprenorphine, naltrexone), but access remains limited by regulatory restrictions, prescriber stigma, and infrastructure gaps. Overdose deaths remain catastrophic.
Stimulant use disorder (cocaine, methamphetamine) affects millions more. There are zero FDA-approved medications. Treatment relies entirely on behavioral interventions.
Nicotine use disorder is the leading cause of preventable death globally. Approved medications help, but relapse rates remain high, particularly when post-cessation weight gain undermines motivation.
A drug class that could address multiple substance use disorders through a shared neurobiological mechanism would be unprecedented.
The Pharmacological Landscape
The incretin-based drugs being studied for addiction vary in their receptor profiles and dosing characteristics:
Single GLP-1 receptor agonists: Semaglutide (Novo Nordisk), exenatide (AstraZeneca), dulaglutide (Lilly), liraglutide (Novo Nordisk). Weekly or daily subcutaneous injection, or oral formulation (semaglutide).
Dual GIP/GLP-1 receptor agonists: Tirzepatide (Lilly, marketed as Mounjaro/Zepbound), brenipatide (Lilly, investigational). Once-weekly or once-monthly subcutaneous injection. Observational data suggests dual agonists may have stronger effects on alcohol-related outcomes.
Triple GIP/GLP-1/glucagon receptor agonists: Retatrutide (Lilly, investigational). Weekly subcutaneous injection. Not yet studied for addiction indications but its multi-receptor profile makes it a logical candidate.
Novel GLP-1 agonists for addiction: BT-001 (Baseline Therapeutics), designed specifically for substance use disorders rather than metabolic disease.
The variety of molecules in the pipeline means that if the class proves effective for addiction, there will likely be multiple options with different dosing schedules, side effect profiles, and receptor engagement patterns. This is important because personalization matters in addiction medicine.
Questions That Remain
The field is moving fast, but significant unknowns persist.
Does it work in treatment seekers? The most cited clinical trial (Hendershot et al., 2025) enrolled non-treatment-seeking participants. Whether GLP-1 agonists can facilitate intentional abstinence or prevent relapse, rather than simply reducing consumption in people not trying to quit, is untested in a large trial.
What's the right dose? The semaglutide trial used low doses (0.25-1.0 mg/week), well below the 2.4 mg/week dose used for obesity. Higher doses might produce larger effects on drinking, but also increase gastrointestinal side effects. The CRAVE study will test the full 2.4 mg dose.
Does BMI matter? The exenatide EXALT trial only showed significant effects in participants with BMI ≥30. Whether leaner individuals respond equally is unclear. Some trials have BMI cutoffs; others do not. Brenipatide's trials require BMI data but do not appear to exclude lower-BMI participants.
Single vs. dual agonism? Observational data suggests dual GIP/GLP-1 agonists like tirzepatide may have stronger effects on alcohol outcomes than GLP-1-only drugs. Whether this holds in randomized trials will be a key question.
Weight loss as a confounder? GLP-1 agonists cause significant weight loss. In the semaglutide trial, participants lost an average of 5% body weight. For people with normal or low body weight, this could be a safety concern. Disentangling the direct neurological effects from weight-related metabolic changes is methodologically challenging.
Long-term durability? All trials to date are 6-12 months. Whether the reduction in craving and consumption persists long-term, and whether it continues after the drug is discontinued, is unknown.
The Bigger Picture for Peptide Science
What's happening with GLP-1 agonists and addiction is part of a broader pattern: peptide therapeutics are moving into territory that was once considered the exclusive domain of small molecule drugs and biologics.
BPC-157 is studied for tissue repair across multiple organ systems. Thymosin alpha-1 is used in immunology. KPV is explored for inflammatory bowel disease. MOTS-c is investigated for metabolic regulation. Selank and semax target cognitive function and anxiety. These are all peptides operating in therapeutic areas where peptides were once considered irrelevant.
The incretin story adds neuroscience and psychiatry to that expanding list. If brenipatide or semaglutide receives an FDA indication for AUD, it will be among the first synthetic peptides approved for a primary neuropsychiatric condition. That precedent will change how researchers, investors, and clinicians think about what peptides can do.
For the peptide research community, the implications are clear. The molecules being studied in labs today, the GLP-1 analogs, the neuropeptides, the signaling peptides, may have applications that no one has thought to test yet. The gap between a peptide's known mechanism and its unexplored potential is where the next brenipatide-scale discovery lives.
Key Takeaways
- GLP-1 receptor agonists reduce alcohol consumption, craving, and substance-seeking behavior through direct effects on brain reward circuitry
- Clinical evidence is strongest for AUD (15+ trials, including two completed RCTs) with positive signals for nicotine and preclinical data for opioids and stimulants
- Multiple molecules are in development: semaglutide, tirzepatide, brenipatide, exenatide, and novel purpose-built compounds
- The treatment gap is vast: 29M Americans with AUD, no new approved drug in nearly 20 years, fewer than 10% receiving medication
- Dual GIP/GLP-1 agonists may offer advantages over GLP-1-only drugs based on observational data
- Open questions include optimal dosing, role of BMI, long-term durability, and effects in treatment-seeking populations
- For peptide science, this represents an expansion into neuroscience and psychiatry that could reshape the field's trajectory
References
1. Hendershot CS, et al. Once-Weekly Semaglutide in Adults With Alcohol Use Disorder. JAMA Psychiatry. 2025;82(4):395-405.
2. Klausen MK, et al. The role of glucagon-like peptide 1 (GLP-1) in addictive disorders. British Journal of Pharmacology. 2019;176(14):2396-2409.
3. Leggio L, et al. GLP-1 Therapeutics and Their Emerging Role in Alcohol and Substance Use Disorders. Journal of the Endocrine Society. 2025.
4. Qeadan F, et al. GLP-1 receptor agonist association with reduced opioid overdose and alcohol intoxication. 2025.
5. Sinha P, Ghosal S. Distilling the evidence for GLP-1 receptor agonists in alcohol use disorder. Addiction Science & Clinical Practice. 2025.
6. ClinicalTrials.gov. RENEW-ALC-2 (NCT07219953), CRAVE (NCT07218354).
7. BioSpace. Baseline Debuts To Challenge GLP-1 Giant Lilly in Alcohol Use Disorder. January 2026.
8. Endocrine Society. GLP-1s show promise in treating alcohol and drug addiction. October 2025.