Pain Sensitivity, Alcohol-Induced Analgesia, and Heavy Drinking in Individuals With Opioid Use Disorder

The goal of this clinical trial is to examine whether individuals with co-occurring opioid use disorder and alcohol use (OUD+ALC) experience heightened pain sensitivity, pain-related negative affect, and greater alcohol reinforcement compared with alcohol-only (ALC) or opioid-only (OUD-ALC) users. The main questions it aims to answer are: * Aim 1. Do individuals with OUD+ALC experience increased pain and pain-related negative affect during periods of sobriety relative to mono-users of alcohol (ALC only) and opioids (OUD-ALC)? * Aim 2. Do individuals with OUD+ALC experience greater alcohol-induced analgesia and alcohol reinforcement compared with mono-users of alcohol (ALC only) and opioids (OUD-ALC)? Participants will: * Complete a screening session * Complete one lab session including a comprehensive assessment battery involving multimodal assessments of pain during sobriety * Complete two experimental lab sessions that will include intravenous (IV) administration of either 80mg% alcohol or placebo (saline), order counterbalanced, to measure alcohol's acute effects on pain and pain-related negative affect

Inclusion Criteria: ALC Only Group: * 21-65 years old * Required to meet NIAAA criteria for heavy drinking (Male: Consuming 5 or more drinks on any day or 15 or more per week; Female: consuming 4 or more on any day or 8 or more drinks per week) OUD + ALC Group: * 21-65 years old * Required to meet NIAAA criteria for heavy drinking (Male: Consuming 5 or more drinks on any day or 15 or more per week; Female: consuming 4 or more on any day or 8 or more drinks per week) * Meet DSM-5 criteria for current opioid use disorder (OUD) * Report using recreational opioids at least weekly (past month) OUD-ALC Group: * 21-65 years old * Meet DSM-5 criteria for current OUD * Report using recreational opioids at least weekly (past month) * Meet "light drinking" criteria (consuming equal to or less than 4 drinks per week for women or consuming equal to or less than 5 drinks per week for men) * Report at least 1 but no more than 3 binge episodes over the past 12 months Exclusion Criteria: * Serious medical problems * Current medical or psychiatric conditions requiring medication for which alcohol is contraindicated (including prescription opioids) * Any serious medical problems * Sensitivity or allergy to alcohol * Body weight \< 110 or \> 210 lbs for alcohol administration * Injury, trauma, nerve/tissue damage, or deformity prohibiting sensory testing * Moderate to severe substance use disorders other than alcohol use disorder (AUD) or OUD * Current severe mental illness, including mania or psychosis * Currently seeking inpatient/intensive treatment for addictive behaviors * Pregnant or nursing and unwilling to take measures to avoid becoming pregnant during the study (females) * Chronic pain requiring ongoing pain management within the past three months. * Clinically significant alcohol or opioid withdrawal symptoms the day of the lab sessions, defined as a score \>10 on the Clinical Institute Withdrawal Assessment of Alcohol Scale Revised (CIWA-Ar) or a score \>12 on the Clinical Opioid Withdrawal Scale (COWS) * Positive alcohol breath test or opioid urine screen the day of the experimental lab sessions to avoid the potential for alcohol-opioid interactions. * Smoking more than 6 cigarettes per day (or alternative form equivalent) * Not fluent in English