Oxytocin
Published research and evidence base
Oxytocin is a nine-amino-acid neuropeptide synthesised in the hypothalamus, with intranasal administration used since the mid-2000s as a research tool for probing social cognition, threat processing and affiliative behaviour in humans. The field is unusually large and unusually contested: early small-sample findings of enhanced trust, emotion recognition and amygdala modulation have been followed by large registered trials and preregistered meta-analyses showing small, heterogeneous and frequently null effects. Current syntheses point to sex-dependent amygdala modulation, a thalamus-striatum-insula circuit as the most reproducible neural signature, and a small significant signal in schizophrenia spectrum disorders. Intranasal delivery to the brain, dose-response and the appropriate outcome measures all remain methodologically unresolved.
- Studies cited
- 21
- Published 2023+
- 16
- Newest paper
- 2026
- Last reviewed
- Aug 2026
Recurring themes in the literature
- social cognition
- intranasal administration
- amygdala reactivity
- autism spectrum disorder trials
- trust and affiliation
- publication bias and replication
- dose-response and inverted-U
- sex differences
- stress and cortisol
Compound identifiers
- CAS
- 50-56-6
- PubChem
- 439302
What Oxytocin is, chemically.
- Molecular formula
- C43H66N12O12S2
- Molecular weight
- 1007.2 g/mol
- CAS number
- 50-56-6
- PubChem CID
- 439302
Pitocin, Ocytocin
These figures come from the PubChem record for this compound and describe the free base. Lyophilised peptide is normally supplied as an acetate or trifluoroacetate salt and carries residual water, so the mass of powder in a vial is not the same quantity as the molecular weight above would suggest. Chromatographic purity on a certificate of analysis does not resolve that difference either — how to read a certificate of analysis explains why.
21 published studies.
Ordered by strength of study design, then by recency. Every entry links to its source record so the finding can be checked against the paper rather than taken on our word.
- 01Systematic review2026
Does intranasal oxytocin reduce symptoms of mental disorders? A meta-analysis of clinical trials
Bonnieux J, et al. · Neuroscience and Biobehavioral Reviews · meta-analysis of 42 double-blind randomised controlled trials, pooled N=1922
The pooled treatment effect was small and non-significant with substantial heterogeneity (g = 0.17, 95% CI -0.05 to 0.38, I-squared 77.4%), falling to g = 0.05 with zero heterogeneity after removing two substance-use-disorder outliers. A small significant effect remained in schizophrenia spectrum disorders (g = 0.12, 95% CI 0.01 to 0.23).
- 02Systematic review2026
A systematic review and meta-analysis of oxytocin modulation of amygdala responses to emotional stimuli and implications for anxiolytic effects
Guo X, Zhang L, Zhang Q, Kendrick KM, Yao S · Neuroscience and Biobehavioral Reviews · meta-analysis of 55 neuroimaging studies, 3337 participants
Oxytocin's effect on amygdala activity was gender-dependent: inhibition in males and enhancement in females. Activation likelihood estimation showed reduced activity in the centromedial subregion and bidirectional effects in the basolateral subregion.
- 03Systematic review2026
Effects of exogenous oxytocin on human brain function are regulated by oxytocin gene expression: A meta-analysis of 20 years of oxytocin neuroimaging and transcriptomic analyses
Wang J, et al. · Neuroscience and Biobehavioral Reviews · neuroimaging meta-analysis and transcriptomic analysis across 75 task-fMRI experiments, n=2247
Consistent domain-general effects appeared in left thalamus, pallidum, caudate and insula, but not the amygdala. These regions formed an integrated thalamus-striatum-insula circuit enriched for CD38, OXT and OXTR expression.
- 04Systematic review2026
Using EEG to Measure the Neural Effects of Oxytocin Administration: A Meta-Analysis and Systematic Review
Deilhaug E, et al. · Psychophysiology · systematic review and meta-analysis of EEG studies of oxytocin administration
The review synthesised electrophysiological evidence for central effects of administered oxytocin, addressing whether EEG provides a more sensitive readout than behavioural endpoints.
- 05Systematic review2026
Intranasal oxytocin for alcohol use disorder: A systematic review and multilevel, bayesian, and variance meta-analyses of randomized clinical trial data
Santos VH, et al. · Psychoneuroendocrinology · systematic review with multilevel, Bayesian and variance meta-analyses of randomised clinical trial data in alcohol use disorder
The review pooled randomised trial evidence for intranasal oxytocin in alcohol use disorder using multiple synthesis frameworks, addressing the heterogeneity that had driven outlier effects in earlier pooled analyses.
- 06Systematic review2025
Effects of oxytocin administration on non-social executive functions in humans: a preregistered systematic review and meta-analysis
Kang H, et al. · Molecular Psychiatry · preregistered meta-analysis of 20 effect estimates from 13 eligible studies (PROSPERO CRD42022308149)
There was no overall significant effect on non-social executive function (Hedges' g = 0.07, p = 0.30). A significant effect emerged only for cognitive flexibility (g = 0.2, p = 0.02), with moderate Bayesian support for absence of publication bias.
- 07Systematic review2025
A multiverse meta-analysis of oxytocin administration studies
Kang H, Deilhaug E, Walle KM, Sartorius AI, Quintana DS · Biological Psychology · 256 distinct meta-analyses across 530 effect sizes from 185 studies, systematically varying inclusion criteria, synthesis models and bias-correction methods
Summary estimates ranged from d = -0.16 to d = 1.45 depending on analytic choices, yet over 90% of the specifications exceeded bootstrapped null distributions. Neurotypical samples and multiple-administration designs yielded larger effects.
- 08Systematic review2025
Dose-response effects of exogenous oxytocin on social cognition: A systematic review
Barton S, Pruin A, Schulze J, Kiebs M, Scheele D, Hurlemann R · Neuroscience and Biobehavioral Reviews · systematic review of intranasal doses from 1 IU to 48 IU in healthy adults; emotion recognition, empathy and interpersonal trust
Most studies used 24 IU and generally reported improved emotion recognition, empathy and trust, though divergent findings at the same dose occurred. Support for the inverted-U dose-response model came largely from studies lacking direct dose comparisons.
- 09Systematic review2024
The effects of oxytocin administration on social and routinized behaviors in autism: A preregistered systematic review and meta-analysis
Audunsdottir K, et al. · Psychoneuroendocrinology · preregistered frequentist and Bayesian meta-analysis of oxytocin administration trials in autism
A small significant effect was found for social outcomes (d = 0.22, p < 0.001) but not routinised behaviours (d = 0.14, p = 0.22). Publication-bias assessments indicated the social effect size may be inflated.
- 10Systematic review2023
Endogenous oxytocin and human social interactions: A systematic review and meta-analysis
Burenkova OV, et al. · Psychological Bulletin · 63 studies in qualitative synthesis, 51 pooled, n=3741 participants, publications 1970 to July 2020
Social interaction did not produce the expected endogenous oxytocin response in causal designs (pre-post g = 0.079; between-condition g = 0.256), while correlational designs showed a small non-zero association (z = 0.137). The authors called for standardised measurement of oxytocin concentrations.
- 11Human clinical2026
Intranasal Oxytocin for Alcohol Use Disorder: A Randomized, Double-Blind, Placebo-Controlled Multisite Trial Assessing Efficacy and Safety
Tiouririne NA, et al. · Alcohol, Clinical & Experimental Research · 12-week double-blind placebo-controlled multisite trial, n=100 with alcohol use disorder, up to 70 IU/day intranasal oxytocin
No significant between-group difference was observed in percentage of heavy drinking days over the 10-week maintenance phase, and secondary drinking outcomes followed the same pattern. Participants on oxytocin scored significantly lower on anger and physical aggression at end of treatment, and tolerability was good.
- 12Human clinical2026
Post-encoding administration of oxytocin selectively enhances memory consolidation of male faces in females
Liu W, Li J, Chen Z, Zhao Q, Sun X · Proceedings of the National Academy of Sciences of the United States of America · three preregistered randomised double-blind placebo-controlled trials, total N=445 (227 male, 218 female), oxytocin given post-encoding, pre-retrieval or pre-encoding
Post-encoding oxytocin, but not pre-retrieval or pre-encoding administration, improved female participants' recognition of male faces 24 h later, with no equivalent effect in males. The authors localised the effect to consolidation rather than encoding or retrieval.
- 13Human clinical2026
Intranasal Oxytocin and Physical Intimacy for Dermatological Wound Healing and Neuroendocrine Stress: A Randomized Clinical Trial
Schneider E, et al. · JAMA Psychiatry · double-blind randomised placebo-controlled trial, 80 heterosexual couples (N=160, mean age 27.6), 7 days twice-daily oxytocin or placebo with suction-blister wounds and 5-day ecological momentary assessment
Couples receiving oxytocin alongside a structured partner appreciation task showed improved wound healing (b = -0.125, P = .048), though this was not robust in sensitivity analyses. Oxytocin combined with affectionate touch or sexual activity was associated with reduced wound severity, and greater sexual activity with lower daily cortisol.
- 14Human clinical2025
Intranasal oxytocin for apathy in people with frontotemporal dementia (FOXY): a multicentre, randomised, double-blind, placebo-controlled, adaptive, crossover, phase 2a/2b superiority trial
Coleman KKL, et al. · The Lancet Neurology · adaptive crossover phase 2a/2b trial across 11 clinics in Canada and the USA, 94 participants, 72 IU intranasal oxytocin twice daily on varying schedules vs placebo
Oxytocin every third day improved the Neuropsychiatric Inventory apathy score by an estimated -1.32 points relative to placebo (95% CI -2.43 to -0.21, one-sided p = 0.010) and was well tolerated, with no adverse events attributed to treatment.
- 15Human clinical2024
The effect of intranasal oxytocin on neurocognition in people with schizophrenia: A randomized controlled trial
İmamoğlu A, Stiles BJ, Jarskog LF, Pedersen CA, Elliott T, Penn DL · Journal of Psychiatric Research · 12-week randomised controlled trial, n=67 participants with schizophrenia or schizoaffective disorder, comprehensive neuropsychological battery at baseline and 12 weeks
Intranasal oxytocin did not significantly improve cognition compared with placebo. The authors noted that timing of cognitive assessment relative to dosing was not standardised.
- 16Human clinical2024
Effects of four-week intranasal oxytocin administration on large-scale brain networks in older adults
Liu P, et al. · Neuropharmacology · randomised controlled trial of four-week intranasal oxytocin in older adults, resting-state network analysis
Four weeks of intranasal oxytocin altered large-scale brain network organisation in older adults, one of the few chronic-dosing neuroimaging datasets in an ageing sample.
- 17Human clinical2021
Intranasal Oxytocin in Children and Adolescents with Autism Spectrum Disorder
Sikich L, et al. · The New England Journal of Medicine · 24-week placebo-controlled phase 2 trial, n=290 randomised (146 oxytocin, 144 placebo), ages 3-17, target 48 IU intranasal daily
The least-squares mean change in ABC modified Social Withdrawal score was -3.7 with oxytocin and -3.5 with placebo (difference -0.2, 95% CI -1.5 to 1.0, P = 0.61). Secondary outcomes generally did not differ, making this the definitive negative trial in autism.
- 18Human clinical2007
Oxytocin improves "mind-reading" in humans
Domes G, Heinrichs M, Michel A, Berger C, Herpertz SC · Biological Psychiatry · randomised double-blind placebo-controlled crossover, healthy male volunteers, Reading the Mind in the Eyes Test
Intranasal oxytocin improved performance on the Reading the Mind in the Eyes Test relative to placebo, particularly for difficult items. This established the emotion-recognition paradigm used throughout the subsequent literature.
- 19Human clinical2005
Oxytocin increases trust in humans
Kosfeld M, Heinrichs M, Zak PJ, Fischbacher U, Fehr E · Nature · placebo-controlled trust game experiment in healthy male volunteers
Intranasal oxytocin increased investors' transfers in a trust game relative to placebo without altering behaviour in a matched risk task. This is the foundational human study of the field; subsequent large replication attempts have not consistently reproduced the effect.
- 20Review2021
Advances in the field of intranasal oxytocin research: lessons learned and future directions for clinical research
Quintana DS, et al. · Molecular Psychiatry · methodological review of intranasal oxytocin trial design
The review catalogued dose selection, delivery device, timing, sex and context as major sources of heterogeneity, and set out design recommendations that later preregistered meta-analyses adopted.
- 21Review2016
Intranasal Oxytocin: Myths and Delusions
Leng G, Ludwig M · Biological Psychiatry · critical quantitative review of intranasal delivery pharmacology
The authors argued that the quantity of oxytocin reaching central receptors after intranasal dosing is very small relative to endogenous release, and that many reported behavioural effects are underpowered and statistically fragile.
What this evidence does not establish.
The proportion of an intranasal dose that reaches central oxytocin receptors has never been directly quantified in humans, and no validated peripheral biomarker of central engagement exists. The largest randomised trial in autism was fully null, effect sizes across domains are small and highly sensitive to analytic choices, dose-response is not established from direct within-study dose comparisons, and effects appear to differ by sex and context in ways not yet predictable at the individual level. There is no approved indication for cognitive or social enhancement.
Common questions about the research.
- What is oxytocin?
Oxytocin is an endogenous nonapeptide produced in the hypothalamus, with an identified receptor in peripheral tissue and central projections to limbic and brainstem regions. In research it is best known from social-neuroscience studies using intranasal administration in healthy volunteers.
- How settled are the social-behaviour findings?
Not very. The early trust and emotion-recognition results are widely cited but have attracted sustained methodological criticism over sample size, replication, and how much intranasally applied peptide reaches the brain. Current review guidance treats the field as unresolved and calls for pre-registered, larger-sample designs.
- What did the largest randomised trial of intranasal oxytocin in autism find?
It was null. The 24-week placebo-controlled phase 2 trial randomised 290 participants aged 3 to 17 to intranasal oxytocin or placebo at a target of 48 IU daily. The least-squares mean change in the ABC modified Social Withdrawal score was -3.7 with oxytocin and -3.5 with placebo, a difference of -0.2 (95 percent CI -1.5 to 1.0, P = 0.61), and secondary outcomes generally did not separate. A 2024 preregistered meta-analysis found a small significant pooled effect on social outcomes (d = 0.22) that publication-bias assessment suggested may be inflated.
Available from our catalog
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