Oxytocin

Oxytocin is a nine-amino-acid peptide made in the hypothalamus and released from the posterior pituitary. Synthetic oxytocin (Pitocin, Syntocinon) is an approved medicine used to induce or speed up labour and to control bleeding after birth. Nasal sprays sold online for mood, trust or bonding are a separate, largely unregulated market.

1. 1

   Binds oxytocin receptors on uterine smooth muscle, causing coordinated contractions that increase in strength and frequency with dose.

2. 2

   Acts on myoepithelial cells around breast ducts to trigger milk ejection during feeding.

3. 3

   In the brain, oxytocin acts on reward and social-salience circuits — the basis for 'bonding' claims, which are far better established in animals than in people.

4. 4

   It also has mild antidiuretic activity, which is why high doses with large fluid volumes can dilute sodium in the blood.

• Reliable, dose-dependent uterine contractions
• Reduced bleeding after birth when used as part of active management of the third stage
• Small, inconsistent effects on social behaviour in autism trials, with the largest studies showing no clear benefit
• Intranasal studies in healthy volunteers show modest shifts in trust and attention to social cues

1. 01World Health Organization — Recommendations for the prevention and treatment of postpartum haemorrhage
2. 02European Medicines Agency — Syntocinon product information
3. 03Intranasal oxytocin and social behaviour trials — PubMed literature search

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.