The purpose of this pilot study is to determine the tolerability, feasibility, and preliminary effectiveness of intranasal oxytocin administration prior to motivational enhancement group therapy sessions on laboratory-based measures of addiction, social connectedness, and stress responsivity in methamphetamine(meth)-using men who have sex with men (MSM). The investigators propose a randomized, double-blind, study of intranasal oxytocin versus placebo 40 IU prior to each of six Motivational Interviewing Group Therapy (MIGT) sessions in 28 mixed HIV sero-status MSM initiating treatment for amphetamine use disorder.

The high prevalence of amphetamine use disorder (AUD) among men who have sex with men (MSM) leads to significant health disparities, including increased risk for HIV sero-conversion. Reducing methamphetamine use mitigates HIV risk. Currently no psychopharmacological agent exists for the treatment of AUD; innovative interventions are desperately needed. Oxytocin, a social neuropeptide, has well-studied anti-addiction effects in animal models of substance dependence. The use of intranasal oxytocin for a variety of human substance use disorders is under early investigation, although no one has studied oxytocin's effects in AUD. In other populations, oxytocin's effects are known to vary depending on social context. Psychosocial treatment alone has been shown to reduce methamphetamine and HIV risk in MSM at a community-based clinic in San Francisco, The Stonewall Project. The investigators propose a randomized, double-blind pilot study of psychopharmacological-psychosocial combination therapy, administration of intranasal oxytocin versus placebo prior to six Motivational Interviewing Group Therapy (MIGT) sessions, in 28 mixed HIV sero-status MSM initiating treatment for AUD. The investigators aim to assess: 1) tolerability, 2) feasibility for larger randomized controlled trials, and 3) exploratory measures of efficacy, including: a) urine levels of methamphetamine and metabolites, b) methamphetamine craving, c) engagement in MIGT through third-party coding of videotaped group sessions and self-reported measures of group connectedness, d) psychophysiological stress responses to group engagement, and e) sexual risk taking.

Inclusion Criteria:

1. One documented urine toxicology screen positive for meth in the past month
2. Considering initiating treatment for Methamphetamine Use Disorder or initiated treatment within the past month
3. History of sexual contact with men.

Exclusion Criteria:

1. Urine toxicology screen positive for heroin in the past month
2. Meeting Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria for current psychotic disorder, severe neuropsychological disorder, current moderate-severe alcohol use disorder, or suicidal or homicidal ideation with intent within the past 90-days
3. Hemodialysis or inability to produce urine samples
4. Sensitivity to: E 216, E 218, and chlorobutanol hemihydrate (preservatives used in nasal spray)
5. Nasal Obstruction or discharge
6. Using Hormone supplementation