Posttraumatic stress disorder (PTSD) is a chronic, debilitating anxiety disorder that may develop after direct or indirect exposure to traumatic events. Prolonged Exposure (PE) is a cognitive-behavioral psychotherapy modality with a wealth of empirical support demonstrating its efficacy to treat PTSD in a variety of populations. The neuropeptide oxytocin is a promising new pharmacotherapeutic agent with prominent anxiolytic effects . Despite a strong biological and theoretical rationale for investigating the potential effectiveness of augmenting PE with intranasal oxytocin, no studies to date have done so. The current study aims to address this important gap in the literature by examining changes in PTSD symptoms following PE treatment combined with a) 40 IU of intranasal oxytocin or b) placebo.

Inclusion Criteria:

1. Male or female; any race or ethnicity; age 18-75 years.
2. Able to provide informed consent and function at an intellectual level sufficient to allow accurate completion of the assessment instruments.
3. Participants must be able to comprehend English.
4. Meet DSM-5 criteria for current PTSD (assessed via the Clinician Administered PTSD Scale; CAPS).
5. A CAPS score of 50 or greater.
6. Participants may also meet criteria for a mood disorder (except bipolar affective disorder, see Exclusion Criteria) or anxiety disorders (e.g., agoraphobia, social phobia, generalized anxiety disorder). The inclusion of participants with affective and anxiety disorders is essential because of the marked frequency of the co-existence of mood and other anxiety disorders among patients with PTSD.
7. Participants taking psychotropic medications will be required to be maintained on a stable dose for at least eight weeks before study initiation. Initiation or change of psychotropic medications during the course of the trial may interfere with interpretation of results.

Exclusion Criteria:

1. Participants meeting DSM-5 criteria for a history of or current psychotic or bipolar affective disorders, or with current suicidal or homicidal ideation and intent. Those participants will be referred clinically.
2. Participants who would present a serious suicide risk or who are likely to require hospitalization during the course of the study. Those participants will be referred clinically.
3. Participants on maintenance anxiolytic, antidepressant, or mood stabilizing medications, which have been initiated during the past 8 weeks.
4. Participants meeting DSM-5 criteria for a substance use disorder, except caffeine or nicotine, within the past 12 months.
5. Pregnant women will be excluded from the proposed study.

2 years.

All adverse events were recorded.