Reduced drug use as an alternative valid outcome in individuals with stimulant use disorders: Findings from 13 multisite randomized clinical trials

A protocol for high-dose lisdexamfetamine and contingency management, alone or in combination, for the treatment of methamphetamine use disorder: The ASCME study

BACKGROUND

The prevalence of methamphetamine use disorder is increasing in North America. Well-evidenced treatment options are currently limited to behavioural interventions, with contingency management (CM) regarded as the most effective approach. Psychostimulants have been identified as a potentially promising treatment for methamphetamine use disorder, particularly at higher doses. This study was designed to examine the effectiveness of a high-dose daily psychostimulant (lisdexamfetamine; LDX) and CM, both alone and in combination, in addition to treatment-as-usual (TAU) for the treatment of moderate-to-severe methamphetamine use disorder.

METHODS

The ASCME study is a multicentre, four-arm, blinded, randomized, placebo-controlled clinical trial examining the effectiveness of adding LDX (250 mg) and CM, alone or in combination, to TAU in reducing days of methamphetamine use among adults with moderate-to-severe methamphetamine use disorder. A total of 440 participants will be randomized across 5 sites to 12 weeks of 1) LDX + TAU + CM; 2) LDX + TAU; 3) placebo + CM + TAU; and 4) placebo + TAU. The primary outcome is reduction in days of self-reported methamphetamine use, with secondary outcomes including treatment retention, sustained abstinence, safety, medication adherence, satisfaction, and quality of life.

CONCLUSION

This study will be the largest study to date examining the effectiveness of a prescribed psychostimulant in the treatment of methamphetamine use disorder, and the first of its kind to employ a four-arm approach to evaluate the added benefit of its combination with CM on psychostimulant treatment. The development of pharmacologic treatments for methamphetamine use disorder remains an urgent research goal.

A single-blind, randomized, controlled contingency management trial on physiological indices and biomarkers of cardiovascular health in people with cocaine use disorder

INTRODUCTION

Limited prospective research has evaluated the health benefits associated with changing levels of drug use, aside from complete abstinence. This study determined whether lower levels of cocaine use impacted physiological indices (e.g., mean arterial pressure) and biomarkers (e.g., stromal cell derived factor-1a [SDF-1a], soluble intercellular adhesion molecule-1 [ICAM-1], neutrophil activating peptide-2 [CXCL7]) of cardiovascular health.

METHODS

Treatment seeking participants enrolled in a 12-week single-blind, randomized, controlled cocaine contingency management trial. Participants were randomly assigned to High Value Reinforcers for cocaine abstinence (n = 41), Low Value Reinforcers for cocaine abstinence (n = 33) or a non-contingent Control group (n = 33). Physiological indices were collected at each clinic visit and averaged over each week of treatment. Biomarkers were assayed at 6-week intervals. Percent benzoylecgonine negative urines matching measurement timeframes were used to predict changes in outcomes using generalized linear models.

RESULTS

Reductions in mean arterial pressure were observed in the High Value group, particularly during follow-up (χ(1,107)2= 6.6, p < .05). Regardless of group, less cocaine use was associated with decreased SDF-1a and increased ICAM-1 and CXCL7 levels (all χ(1,107)2> 4.7; p values < 0.05).

CONCLUSIONS

Improved blood pressure was observed in the High Value treatment group, who provided the greatest percent of cocaine negative urine samples but did not achieve total abstinence. Less cocaine use was also associated with changes in cardiac biomarkers that may indicate tissue repair. These results indicate that less cocaine use, even without complete abstinence, can improve blood pressure, and potentially heal cardiovascular insult, in individuals with Cocaine Use Disorder.

Estimating the Daily Milligrams of Oral Amphetamine Equivalent of Illicit Methamphetamine Use

Introduction

The purity, accessibility, and affordability of illicit methamphetamine has increased in recent decades, which has been linked to rising rates of methamphetamine-involved overdoses, psychosis, cardiovascular events, and other health consequences. Nevertheless, information about the quantity of methamphetamine used by regular consumers has been limited, despite the potential clinical utility of exposure quantification.

Methods

From August 2024-April 2025, self-reported daily methamphetamine consumption was assessed among n=68 individuals. Methamphetamine samples (n=112) were analyzed for purity using liquid chromatography-mass spectrometry. Percent bioavailability by route of administration and stimulant equivalency were obtained from literature. A simulation model leveraging bootstrapping was used to estimate MOAE.

Results

The average reported daily methamphetamine consumption was 0.96g (median 0.36g; range 0.1g-4.0g). Average purity was 71.6% (median 75.5%; range 0.1%-95.0%). Given estimated average bioavailability of 52.0% when smoked, 79.3% when insufflated, 67.2% orally or inserted rectally, and a 2:1 amphetamine-methamphetamine equivalency, the average consumer used 1,549.0 MOAE daily (median 516.6; range 1.3-10,112.0).

Discussion

We estimate that consumers of methamphetamine in Los Angeles use a median daily stimulant dose (>500 MOAE) that is nearly tenfold higher than the maximum typical recommended clinical dose of mixed amphetamine salts (60mg). This may help explain the limited efficacy of prescription stimulant treatment for methamphetamine use disorder, which typically employs considerably lower quantities. Given this high dose, these findings shed light on the rising incidence of methamphetamine-related sequalae, such as psychosis, cardiovascular complications, and sudden death. Although exposure quantification is commonplace for alcohol and tobacco use disorders, uncertainties in illicit drug markets has complicated this practice for most illicit drugs. This study supports leveraging emerging information from drug checking programs so that clinicians can approximate exposure quantification.

Substance use negatively impacts change in reinforcement during the year following substance use treatment

OBJECTIVE

Although research supports an association between increased alternative reinforcement and decreased substance use, the impact of substance use on changes in reinforcement during posttreatment recovery remains untested. This study tested the effect of abstinence duration and substance use frequency on the trajectories of four reinforcement mechanisms, behavioral activation, reward probability, reward barriers, and valued living, from pre- to 12-month posttreatment.

METHOD

Adults in intensive outpatient substance use disorder treatment (N = 206) completed self-report measures of the four reinforcement constructs and substance use over six timepoints from pre- to 12-month posttreatment. Latent curve models were used to test the association between reinforcement trajectories and abstinence duration and substance use frequency, respectively.

RESULTS

Lower substance use frequency was associated with significantly improved behavioral activation, reward probability, and reward barriers across the posttreatment period (ps < .05). Higher substance use frequency was associated with significantly lower valued living at each timepoint (ps < .05). Longer abstinence duration was significantly associated with higher behavioral activation and valued living, and lower reward barriers at 12-months (ps < .05).

CONCLUSIONS

Substance-free reinforcement improves during treatment and is negatively impacted by substance use frequency during posttreatment. Abstinence duration is positively associated with substance-free reinforcement at 12-month posttreatment. These findings support the conceptualization of reinforcement as a malleable treatment target that is negatively impacted by substance use. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Effects of Dictyophora polysaccharide on cerebellar Purkinje cell degeneration in a chronic alcohol mouse model

BACKGROUND

Recent research showed that the NLRP3 inflammasome was activated in the central nervous system of mice administered chronic ethanol (EtOH). Dictyophora polysaccharides (DIPs) are essential components of the valuable edible fungus Dictyophora, which has antioxidant properties that can delay the aging process of the body. This study aimed to investigate the roles of NLRP3 in chronic EtOH-induced cerebellar Purkinje cell (PC) degeneration and behavioral changes.

METHODS

C57BL/6J normal and NLRP3 knockout mice were exposed to EtOH for 14 days. Dictyophora polysaccharide (DIP) and NLRP3 inhibitor were administered to the EtOH mice. The pathology and NLRP3-ASC-caspase-1 signaling pathway proteins were analyzed in EtOH mice cerebellar tissues and behavioral performance was assessed in the mice.

RESULTS

In the EtOH mouse model, we observed increases in the NLRP3 inflammasome proteins, including NLRP3, ASC, caspase-1, mature IL-1β and pro IL-1β, loss of PCs, and motor coordination disorders. We found that DIPs could suppress the NLRP3-ASC-caspase-1 signaling pathway, and alleviate the motor deficits and cerebellar pathological changes in chronic EtOH mice. Next, we used MCC950, a NLRP3 inhibitor, and an NLRP3 knockout strategy to further verify the effects of NLRP3-ASC-caspase-1 signaling in chronic EtOH mice. MCC950 or NLRP3 knockout alleviated the EtOH-induced latency to decreases in fall time, increases in stride width and decreases in stride length. MCC950 or NLRP3 knockout also attenuated PC number loss and suppressed NLRP3 inflammation induced by EtOH. Taken together, pharmacologically or genetically inhibiting NLRP3 alleviated EtOH-induced cerebellar degeneration and behavioral deficits.

CONCLUSION

These findings indicated that DIPs might diminish EtOH-induced cerebellar degeneration and behavioral deficits through the NLRP3-ASC-caspase-1 signaling pathway, which provides a potential therapeutic target for the prevention and treatment of alcoholism and EtOH-induced cerebellar pathology.

The Survival Benefit of Reabstinence After Harmful Alcohol Use Following Early Liver Transplant for Severe Alcohol-Associated Hepatitis: A Multicenter ACCELERATE Study

INTRODUCTION

Early (i.e., without mandated period of abstinence) liver transplant (LT) for alcohol-associated hepatitis is the fastest-growing indication for LT in the United States and Europe. Harmful alcohol use after LT is associated with poor outcomes, but the distinction of establishing abstinence after return to drinking (i.e., reabstinence) is understudied. This study aims to characterize the survival outcomes of achieving reabstinence after post-LT harmful alcohol use.

METHODS

We analyzed early LT recipients from 12 US LT centers between 2006 and 2021. Post-LT alcohol use was characterized as harmful using criteria of "binge" (≥5 [men] or ≥4 [women] drinks in < 24 hours) or "frequent" (≥4 days in one week) by interview or phosphatidylethanol >20 ng/mL. Reabstinence was defined as ≥12 consecutive months without harmful alcohol use after harmful alcohol use.

RESULTS

Among 347 LT recipients (64% male, median age 43, median Model for End-Stage Liver Disease-Sodium score 38) with median post-LT follow-up of 2.2 years (interquartile interval 1.1-3.6), 276 (80%) recipients had no evidence of harmful alcohol use, 35 (10%) recipients had reabstinence, and 36 (10%) recipients had continued harmful alcohol use without reabstinence. Five-year predicted survival, adjusted for age, sex, and Model for End-Stage Liver Disease-Sodium score, was lowest among LT recipients with continued harmful alcohol use (77%), but similar among those with no harmful use (93%) and reabstinence (94%).

DISCUSSION

Achieving reabstinence after post-LT harmful alcohol use is associated with similar 5-year post-LT survival compared with those without evidence of post-LT harmful alcohol use. Our findings highlight the importance of early detection and treatment of post-LT alcohol use.

Opioid use and abuse in adolescents and young adults; dealing with science, laws and ethics: Charming the COBRAS

The subject of substance use disorders in the pediatric population remains a disturbing conundrum for clinicians, researchers and society in general. Many of our youth are at risk of being damaged and even killed by drug addictions that result from the collision of rapidly developing as well as vulnerable central nervous systems encountering the current global drug addiction crisis. A major motif of this chemical calamity is opioid use disorder in adolescents and young adults that was stimulated by the 19th century identification of such highly addictive drugs as morphine, heroin and a non-opiate, cocaine. This analysis focuses on the pervasive presence of opioid drugs such as heroin and fentanyl that has become a major tragedy in the 21st century arising from an overall substance use and misuse phenomenon rampant in global society. Themes covered in this article include the history of addictive drugs in humans, diagnostic terms in use, the role of neurobiology in drug addiction, and current psychopharmacologic approaches to opioid overdose as well as addiction. Our youth are continuously confronted by dangers of high-risk behaviors including death and injury from opioid use disorders due to their central nervous system neuroplasticity as well as the widespread availability of these harmful chemicals. Healthcare professionals should actively assist our youth who unknowingly and even innocently encounter this deadly menace in the 21st century.

SEX-DEPENDENT MODULATION OF BEHAVIORAL ALLOCATION VIA VENTRAL TEGMENTAL AREA-NUCLEUS ACCUMBENS SHELL CIRCUITRY

Diagnostic criteria for substance use disorder, cocaine type (i.e., cocaine use disorder), outlined in the 5 th edition of the Diagnostic and Statistical Manual, imply that the disorder arises, at least in part, from the maladaptive allocation of behavior to drug use. To date, however, the neural circuits involved in the allocation of behavior have not been systematically evaluated. Herein, a chemogenetics approach (i.e., designer receptors exclusively activated by designer drugs (DREADDs)) was utilized in combination with a concurrent choice self-administration experimental paradigm to evaluate the role of the mesolimbic neurocircuit in the allocation of behavior. Pharmacological activation of hM3D(G q ) DREADDs in neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens (AcbSh) induced a sex-dependent shift in the allocation of behavior in rodents transduced with DREADDs. Specifically, male DREADDs animals exhibited a robust increase in responding for a natural (i.e., sucrose) reward following pharmacological activation of the VTA-AcbSh circuit; female DREADDs rodents, in sharp contrast, displayed a prominent decrease in drug-reinforced (i.e., cocaine) responding. The sequential activation of hM3D(G q ) and KORD DREADDs within the same neuronal population validated the role of the VTA-AcbSh circuit in reinforced responding for concurrently available natural and drug rewards. Collectively, the VTA-AcbSh circuit is fundamentally involved in behavioral allocation affording a key target for the development of novel pharmacotherapies.

An exploration of desired abstinent and non-abstinent recovery outcomes among people who use methamphetamine

BACKGROUND

In the United States, complete abstinence persists as the standard for demonstrating recovery success from substance use disorders (SUDs), apart from alcohol use disorder (AUD). Although the FDA has recently indicated openness for non-abstinence outcomes as treatment targets, the traditional benchmark of complete abstinence for new medications to treat SUDs remains a hurdle and overshadows other non-abstinent outcomes desired by people with SUDs (e.g., improved sleep, employment, family reunification). This study sought to expand the definition of recovery to include non-abstinent pathways by exploring non-abstinence-based outcomes desired by people who use methamphetamine (PWUM).

METHODS

Participants (n = 100) were recruited from existing National Institute on Drug Abuse (NIDA) projects including a treatment-seeking sample of people recently released from prison (all of whom endorsed recent methamphetamine use) and a sample of people using syringe service programs. In a convergent survey design, participants responded to closed-ended questions regarding recovery outcomes, followed by open-ended items to gain a better understanding of PWUM and their conception of recovery. The importance of non-abstinent outcomes was measured in five categories (substance use, physical health, cognitive functioning, mental health, and financial/social/relationships).

RESULTS

Participants were primarily White (88%), male (67%), and an average age of 40. Approximately two-thirds of participants agreed that people need to stop all mood- or mind-altering substances to be in recovery (64%). Nevertheless, participants indicated a variety of desired non-abstinent recovery outcomes, both substance-related (e.g. reductions in methamphetamine use) and non-substance-related (e.g. improved economic stability). Specific non-abstinent outcomes endorsed as "absolutely essential" by PWUM included: preventing legal trouble (92%), employment stability (82%), improved quality of life (80%), housing stability (78%), improved coping skills (78%), improved relationships (75%), economic/income stability (74%), ability to think clearly (73%), less impulsivity (73%), less depression (71%), less stress (70%), improved hopefulness (70%), and improved sleep (70%). Open-ended responses emphasized employment stability, economic/income stability, improved coping skills, improved relationships, as well as improved energy, appetite, and sleep.

CONCLUSION

Our findings indicate the importance of non-abstinent recovery outcomes among PWUM, suggesting high acceptability of non-abstinent recovery targets by people with lived experience. Further, the essential importance of non-abstinent outcomes, especially in the financial/social/relationship and mental health domains, were highlighted, providing novel targets for delivering SUD treatment/recovery.

Lisdexamfetamine in the treatment of methamphetamine dependence: A randomised, placebo-controlled trial

AIMS

This study tested the efficacy and safety of a 12-week course of lisdexamfetamine in reducing methamphetamine use, an outcome which is associated with improvements in health and wellbeing, in people dependent on methamphetamine.

DESIGN, SETTING AND PARTICIPANTS

This study was a randomised double-blind placebo-controlled trial conducted in six specialist outpatient clinics in Adelaide, Melbourne, Newcastle and Sydney, Australia (2018-2021). Participants were164 adults with methamphetamine dependence, reporting at least 14 use days out of the previous 28 days (62% male, 38% female, < 1% other; mean age 39 years).

INTERVENTIONS

Participants were randomly allocated 1:1 to a 15-week regimen of lisdexamfetamine (1-week induction to 250 mg, 12-week maintenance regimen, 2-week reduction; n = 80) or matched placebo (n = 84), followed-up to Week 19.

MEASUREMENTS

The primary efficacy measure was past 28-day methamphetamine use at Week 13. Safety was assessed by adverse event rates. Secondary measures included methamphetamine use during the 12-week treatment period and treatment satisfaction.

FINDINGS

Nine randomized participants did not start treatment (five were allocated to lisdexamfetamine and four allocated to placebo) and were excluded from the analyses. Fifty-seven per cent of participants were retained on study medication to primary end-point. There was only weak evidence of a lisdexamfetamine benefit at 13 weeks [adjusted difference in days of methamphetamine use = 2.2, 95% confidence interval (CI) = -0.5 to 5.0; P = 0.49]. However, throughout the whole 12-week treatment maintenance phase, the lisdexamfetamine group had fewer days of methamphetamine use in total (difference = 8.8, 95% CI = 2.7-15.0; P = 0.005). The lisdexamfetamine group reported greater self-reported treatment effectiveness [odds ratio (OR) = 2.89, 95% CI = 1.67-5.02; P < 0.001] and treatment satisfaction (OR = 3.80, 95% CI = 1.93-7.47; P < 0.001). Adverse events with lisdexamfetamine included nausea. Serious adverse events occurred in four (5%) of participants who received lisdexamfetamine.

CONCLUSIONS

Lisdexamfetamine appears to reduce methamphetamine use over a 12-week treatment period, although there is only weak evidence that reduced use is maintained during the last 4 weeks.

Influence of cocaine use reduction on markers of immune function

This study determined the effects of reduced cocaine use on immune function. Treatment seeking participants with Cocaine Use Disorder enrolled in a 12-week contingency management trial to reduce cocaine use. Participants were randomly assigned 1:1:1 to High Value Reinforcers (i.e., $55/negative urine sample) for cocaine abstinence (n = 41), Low Value Reinforcers (i.e., $13/negative urine sample) for cocaine abstinence (n = 33) or Non-Contingent Control (n = 33). Immune measures were collected at 6-week intervals. The High Value group had greatest use reductions, increased erythema and IL-6 and decreased IL-10 and CCL5, suggesting an activated immune response. Cocaine use reduction may promote changes in immune health.

Harm reduction-focused behavioral activation for people who inject drugs: Mixed methods outcomes from a pilot open trial

INTRODUCTION

People who inject drugs (PWID) experience high rates of mental health problems and drug-related harms. Harm reduction-focused interventions aim to reduce harms associated with drug use and are an important approach for engaging people who are not seeking traditional abstinence-focused treatment. Yet, few studies to date have examined the effectiveness of harm reduction psychosocial treatment for drug use. We evaluated the outcomes of a harm reduction-focused behavioral activation (BA) intervention from pretreatment to a 1-month follow-up.

METHODS

A total of N = 23 PWID (65.2 % White; 52.2 % women; mean age 35.4 ± 7.8 years) were recruited from syringe services programs and n = 19 received the intervention via teletherapy. Assessment of study outcome measures occurred at pre- and posttreatment and a one-month follow-up.

RESULTS

Results reflected post-intervention increases in behavioral activation and readiness to change drug use, as well as decreases in substance use, depression, and HIV risk behaviors. There were mixed outcomes on substance-related problems with increases at follow-up, possibly reflecting increased problem recognition.

CONCLUSIONS

These results suggest initial promise for the harm reduction-focused treatment. Additional research with randomized designs and larger sample sizes is needed, and more intensive treatment may be required to support sustained treatment gains in this population.

Worsening trends in the frequency of methamphetamine and other stimulant use between treatment admission and discharge

BACKGROUND

Treatment for methamphetamine and other stimulants can be effective but treatment attrition and continued use are very high. Abstinence is the conventional outcome used to evaluate treatment success, but defining treatment success in this way misses opportunities to promote improved health even when abstinence is not achieved. Reducing methamphetamine and stimulant use without abstinence is associated with many positive outcomes. However, little is known about drug use patterns during treatment or trends in use over time.

METHODS

We used the Treatment Episode Dataset-Discharges (TEDS-D) to identify treatment episodes that had a stimulant drug indicated as the primary substance of use (2017-2021; N=251,841; methamphetamine, cocaine, other amphetamines, or other stimulants). Our outcome was the change in the frequency of drug use between admission and discharge (decreased use with abstinence, decreased use without abstinence, increased use). We used multiple logistic regression to model a change in drug use frequency, predicted by year, stimulant type, and their interaction.

RESULTS

Nearly two-thirds of the sample (60 %) had methamphetamine indicated as the primary stimulant of use. There was a decrease in the predicted rate of abstinence over time and worsening trends were strongest among those using methamphetamine. Daily and periodic drug use at both admission and discharge (no change in use) became worse over time, particularly for those using methamphetamine.

CONCLUSION

Treatment outcomes worsened over time and declined fastest among those reporting methamphetamine. Abstinence was rare and most treatment clients did not change their drug use behavior. We recommend a renewed focus on evidence-based harm reduction while the nation's treatment systems continue grappling with the stimulant crises.

Syringe services program staff and participant perspectives on changing drug consumption behaviors in response to xylazine adulteration

BACKGROUND

Xylazine is an increasingly common adulterant in the North American unregulated drug supply that is associated with adverse health outcomes (e.g., skin infections, overdose). However, there are significant knowledge gaps regarding how xylazine was initially identified and how syringe services program (SSP) staff and clients (people who use drugs) responded to its emergence.

METHODS

From June-July 2023, we conducted qualitative interviews with medical (e.g., clinicians) and frontline SSP staff (e.g., outreach workers) and adult clients with a history of injection drug use at a Miami-based SSP. Inductive memos identified emergent codes; thematic analysis involving team consensus established final themes.

RESULTS

From interviews with SSP staff (n = 8) and clients (n = 17), xylazine emergence was identified at different times, in various ways. Initially, during summer 2022, clients identified a "tranquilizer-like substance" that worsened sedation and withdrawal and caused wounds. SSP medical staff later identified this adulterant as xylazine by treating new medical cases and through diverse information-sharing networks that included professional societies and news sources; however, frontline SSP staff and clients needed additional educational resources about xylazine and its side effects. With limited guidance on how to reduce harm from xylazine, SSP clients altered their drug consumption routes, reduced drug use, and relied on peers' experiences with the drug supply to protect themselves. Some individuals also reported preferring xylazine-adulterated opioids and increasing their drug use, including the use of stimulants to avoid over sedation.

CONCLUSIONS

Xylazine's emergence characterizes the current era of unprecedented shifts in the unregulated drug supply. We found that xylazine spurred important behavioral changes among people who use drugs (e.g., transitioning from injecting to smoking). Incorporating these experiences into early drug warning surveillance systems and scaling up drug-checking services and safer smoking supply distribution could help mitigate significant health harms caused by xylazine and other emergent adulterants.

Protective or potentially harmful? Altering drug consumption behaviors in response to xylazine adulteration

Background

Xylazine is an increasingly common adulterant in the North American unregulated drug supply that is associated with adverse health outcomes (e.g., skin infections, overdose). However, there are significant knowledge gaps regarding how xylazine was initially identified and how syringe services program (SSP) staff and clients (people who use drugs) responded to its emergence.

Methods

From June-July 2023, we conducted qualitative interviews with medical (e.g., clinicians) and frontline SSP staff (e.g., outreach workers) and adult clients with a history of injection drug use at a Miami-based SSP. Inductive memos identified emergent codes; thematic analysis involving team consensus established final themes.

Results

From interviews with SSP staff (n = 8) and clients (n = 17), xylazine emergence was identified at different times, in various ways. Initially, during summer 2022, clients identified a "tranquilizer-like substance" that worsened sedation and withdrawal and caused wounds. SSP medical staff later identified this adulterant as xylazine by treating new medical cases and through diverse information-sharing networks that included professional societies and news sources; however, frontline SSP staff and clients needed additional educational resources about xylazine and its side effects. With limited guidance on how to reduce harm from xylazine, SSP clients altered their drug consumption routes, reduced drug use, and relied on peers' experiences with the drug supply to protect themselves. Some individuals also reported preferring xylazine-adulterated opioids and increasing their drug use, including the use of stimulants to avoid over sedation.

Conclusions

Xylazine's emergence characterizes the current era of unprecedented shifts in the unregulated drug supply. We found that xylazine spurred important behavioral changes among people who use drugs (e.g., transitioning from injecting to smoking). Incorporating these experiences into early drug warning surveillance systems and scaling up drug-checking services and safer smoking supply distribution could help mitigate significant health harms caused by xylazine and other emergent adulterants.