Oxytocin

What it is

Oxytocin is a nine-amino-acid neuropeptide made in the hypothalamus and released from the posterior pituitary. Synthetic oxytocin is an approved medicine, sold under names including Pitocin and Syntocinon, given by infusion or injection in obstetrics to induce or strengthen labour and to reduce bleeding after birth. Intranasal oxytocin is investigational and appears in research on social cognition, autism, and appetite.

How it works

It binds the oxytocin receptor, a G protein-coupled receptor found on uterine smooth muscle and mammary tissue and in brain regions linked to social behaviour; in the uterus, receptor activation drives rhythmic contraction. How much intranasally given oxytocin reaches the human brain, and by which route, is still debated.

Regulatory status

1. Cosmetic ingredient
2. Research compound
3. In clinical trials
4. Approved medicine

Approved as a medicine by the FDA or the EMA for at least one indication. Approval covers the named indication and formulation only.

What published research is studying

• Labour induction and blood loss after birth (randomised trials and Cochrane reviews)
• Social functioning in children and adolescents with autism (intranasal, randomised trials)
• Body weight, food intake, and body composition in adults with obesity (intranasal)
• Trust and social cognition in healthy adults (single-dose laboratory studies)

Key findings

1. 01

   A Cochrane review of 61 trials with 12,819 women found that, compared with expectant management, oxytocin induction left fewer women undelivered vaginally at 24 hours (8.4% against 53.8%), with a small rise in epidural use.

   Alfirevic Z et al., Cochrane Database Syst Rev 2009
2. 02

   In a 24-week Phase 2 trial in 290 children and adolescents with autism, the social withdrawal score changed by -3.7 points with intranasal oxytocin and -3.5 with placebo, a difference that was not significant.

   Sikich L et al., N Engl J Med 2021
3. 03

   In a 12-week randomised trial in 87 children with autism aged 3 to 12, intranasal oxytocin showed no overall effect on caregiver-rated social responsiveness, although an age interaction suggested some effect in children aged 3 to 5.

   Guastella AJ et al., Mol Psychiatry 2023
4. 04

   In a 4-week randomised trial in 32 children with autism aged 6 to 12, intranasal oxytocin improved social responsiveness scores when pretreatment neuropeptide levels were included in the model, and children with the lowest baseline blood oxytocin improved most.

   Parker KJ et al., Proc Natl Acad Sci U S A 2017
5. 05

   In an 8-week randomised trial in 61 adults with obesity, body weight changed by 0.20 kg with intranasal oxytocin and 0.26 kg with placebo, with no difference between groups, although caloric intake at a test meal was 152 kcal lower with oxytocin.

   Plessow F et al., NEJM Evid 2024

How strong is the evidence?

Common questions