Diclofenac as a KMO Inhibitor

Inclusion Criteria: * Ages 21-65 * Meet DSM-5 diagnostic criteria for AUD of any severity (Mild, Moderate, or Severe) Exclusion Criteria: * Lifetime DSM-5 diagnosis of schizophrenia spectrum and other psychotic disorders and bipolar and related disorders * Positive urine toxicology screen for the following substances: cocaine, opiates, amphetamines, methamphetamine, phencyclidine, barbiturates, benzodiazepine, methadone, and tricyclic antidepressants * Self-reported daily use of opioids (including prescribed) * Serious alcohol withdrawal symptoms as indicated by a score ≥ 10 on the Clinical Institute Withdrawal Assessment for Alcohol-Revised * If female: pregnant, nursing, or with reproductive potential who refuses to use reliable methods of birth control throughout the study * Any autoimmune disorder, inflammatory disorder, or medical condition that may interfere with safe study participation and/or study aims (e.g., any cardiac, renal, or liver disease, uncontrolled hypertension, or diabetes) * Attempted suicide in the past 3 years and/or serious suicidal intention or plan within the past year * Currently on prescription medication that contraindicates use of diclofenac, including but not necessarily limited to: oral corticosteroids, anticoagulants, lithium, warfarin, aspirin (daily use), methotrexate, cyclosporine, ACE-inhibitors, and diuretics like furosemide and thiazides * Previously known hypersensitivity, including gastroenteritis, asthma, and allergic-type reactions, to any NSAID and/or aspirin * Current daily use of any NSAID or regular pattern of near daily use within the past three months, regular use of a prebiotic or probiotic supplement and/or any antibiotic, prebiotic, or probiotic use within the last month * Any lifetime history of ulcer disease, gastritis, gastroenteritis, or gastrointestinal bleeding * Current or recent (within 3 months) participation in a clinical trial involving medication administration * Currently in treatment, a history of treatment within the 30 days before enrollment, or currently seeking immediate treatment for AUD * Current (last 12 months) DSM-5 diagnosis of SUD for any psychoactive substances other than alcohol and nicotine * Currently prescribed a psychotropic medication for the treatment of schizophrenia spectrum and other psychotic disorders, bipolar and related disorders * AST and ALT \> four times the upper limit of the normal range, or albumin, GFR, BUN, or creatinine 15% \> the upper limit of the normal range * Suffered a mild or moderate traumatic brain injury (TBI) within the last 12 months, a severe TBI at any point in their life, or a moderate TBI before the age of 12 * Has below a 6th grade reading level * Within the last 3 months, tested positive for COVID-19 (i.e. the SARS-CoV-2 virus) and experienced common related symptoms * Any other circumstances that, in the opinion of the investigators, compromises participant safety, ability of the investigators to conduct the study as designed, and/or study integrity