Overview
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In plain language
Oxytocin is a natural hormone of 9 amino acids. It makes the uterus contract during labor and releases milk during breastfeeding.
As a medicine (Pitocin and generics), it is used in hospitals to start or strengthen labor and to prevent heavy bleeding after birth. It is sometimes called the "love hormone" because it affects social behavior and bonding, but nasal sprays for those uses are still experimental.
For students
Oxytocin (CYIQNCPLG-NH2, about 1,007 Da) is made in the hypothalamus and released from the posterior pituitary. It has a six-residue ring formed by a Cys1–Cys6 disulfide bond and a three-residue tail. Vincent du Vigneaud determined its structure and synthesized it in 1953, the first peptide hormone made in a lab, earning the 1955 Nobel Prize in Chemistry.
It differs from vasopressin at only two positions (3 and 8). It acts on the oxytocin receptor, a GPCR whose numbers in the uterus rise sharply near term.
For researchers and instructors
Clinical use. Labor induction and augmentation; prevention and treatment of postpartum hemorrhage. Carbetocin, a heat-stable analogue, is used in many countries.
Safety. Uterine hyperstimulation and fetal distress; water intoxication and hyponatremia with high doses because of weak vasopressin-like activity.
Behavioral research. Intranasal oxytocin studies in autism, social cognition and psychiatric conditions have produced inconsistent results; how much reaches the brain is debated.
Status. FDA-approved for obstetric use.
Molecular identity
- Amino acids
- 9
- Molecular weight
- ~1,007.2 Da
- Formula
- C₄₃H₆₆N₁₂O₁₂S₂
- Sequence
- CYIQNCPLG-NH₂ (Cys1–Cys6 disulfide)
Sequence map
Hydropathy
Kyte–Doolittle score per residue. Positive values are water-repelling.
Origin and history
In 1906 the British scientist Henry Dale found that pituitary extracts make the uterus contract. The hormone responsible was named oxytocin, Greek for “quick birth.” In 1928 Oliver Kamm’s team at Parke-Davis separated it from vasopressin.
In 1953 Vincent du Vigneaud at Cornell sequenced and synthesized oxytocin, the first peptide hormone ever made in a lab, and won the 1955 Nobel Prize in Chemistry. Synthetic oxytocin (Pitocin) is still used to start labor. In the 1990s studies in prairie voles by Sue Carter, Thomas Insel and others linked it to pair bonding, earning it the nickname “love hormone.”
Key people
- Henry DaleDiscovered its effect (1906)
- Vincent du VigneaudNobel Prize in Chemistry 1955
- Sue CarterLinked oxytocin to social bonding
Timeline
- 1906
Uterus-contracting effect discovered
- 1928
Separated from vasopressin
- 1953
Sequenced and synthesized
- 1955
Nobel Prize to du Vigneaud
- 1990s
Social bonding research
See every peptide on one history timeline.
Human evidence
Approved to start or strengthen labor and to control bleeding after birth. Nasal oxytocin has been studied for social and psychiatric conditions, with mixed results.
Registration and enrollment are not proof of benefit; check study results directly.
Explore original publications and distinguish preclinical findings from controlled human evidence.
Safety and regulatory status
See every compound on the regulatory tracker.
FDA-approved for obstetric use (Pitocin and generics). Nasal use is investigational in the U.S.
This profile is educational and does not provide treatment, dosing or sourcing guidance.
Sources
- PubMed literature search: Oxytocin
- PubChem compound search: Oxytocin
- DailyMed (FDA label search): Oxytocin
- Nobel Prize in Chemistry 1955
- ClinicalTrials.gov search: Oxytocin
Hernandez Gener, E. (2026, November 7). Oxytocin: molecular data, research history and evidence. VALREXA Biosciences. https://valrexa.com/peptides/oxytocin.html
APA style · Last reviewed November 7, 2026 · Our editorial standardsLast reviewed November 7, 2026. Trial and regulatory status can change; confirm in the linked registries. This profile is educational and is not medical advice, a treatment recommendation, or dosing or sourcing guidance. Report an error · Corrections policy