Oxytocin is an endogenous cyclic nonapeptide hormone (Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 with a disulfide bridge between Cys1 and Cys6, MW ~1007.2 g/mol) produced in the hypothalamus and released from the posterior pituitary. Synthetic oxytocin (Pitocin) is one of the most widely used medications in obstetrics, FDA-approved for labor induction and augmentation, and for control of postpartum hemorrhage. It acts on oxytocin receptors in the uterine myometrium to stimulate rhythmic contractions and on mammary myoepithelial cells to facilitate milk ejection.
Category: Reproductive / Hormonal. Evidence rating: A (strong human clinical data).
Clinical status: FDA-approved (Pitocin for labor induction, augmentation of labor, and postpartum hemorrhage)
Oxytocin binds to the oxytocin receptor (OXTR), a Gq/11-coupled GPCR expressed in uterine myometrium, mammary tissue, and the central nervous system. Receptor activation triggers phospholipase C-mediated hydrolysis of PIP2 to IP3 and DAG, causing intracellular calcium release from the sarcoplasmic…
Research base: 0 registered clinical trials and 12 indexed publications reference Oxytocin.
Safety considerations: Uterine hyperstimulation/tachysystole: can cause excessive contractions leading to fetal distress; requires continuous fetal monitoring; Water intoxication and hyponatremia: oxytocin has antidiuretic properties at high doses; risk increases with prolonged infusion and hypotonic IV fluids; Uterine rupture: rare but life-threatening, especially in patients with prior uterine surgery.
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-07-05.
Related peptides: Kisspeptin, Gonadorelin, Vasopressin.
Compare: Oxytocin vs Kisspeptin, Oxytocin vs Gonadorelin, Oxytocin vs Vasopressin.
Pitocin is the brand name for synthetic oxytocin given intravenously in hospitals. It is primarily used to induce labor when medically necessary (e.g., post-dates pregnancy, preeclampsia), to augment slow labor, and to prevent or treat postpartum hemorrhage by promoting uterine contraction after delivery.
Despite initial promising small studies, the largest randomized trial (SOAR, NEJM 2021, n=290) found no benefit of 24 weeks of intranasal oxytocin over placebo for social functioning in children and adolescents with autism. The evidence does not support routine use for social enhancement.
Intranasal oxytocin has been used off-label to facilitate the milk let-down reflex, but Cochrane reviews found insufficient evidence to recommend routine use. It may be considered in select cases of documented let-down difficulties under medical supervision.
The main risks include uterine hyperstimulation (excessive contractions that can compromise fetal oxygen supply), water intoxication with prolonged high-dose infusion, and rarely uterine rupture. Continuous fetal heart rate monitoring is required during oxytocin administration.