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Research profile · Peptide

Oxytocin

Also known as Oxytocin acetate

Clinical — evidence level 4 of 4: Established clinical evidencePrescription only — UK regulatory status: Prescription-only medicine (UK)

Overview

A nonapeptide hormone. A prescription-only medicine in the UK, licensed for obstetric use only.

Category
Peptide
Highest evidence level identified
Established clinical evidence
Last scientifically reviewed
20 August 2026
Last regulatory review
20 August 2026

Mechanism under investigation

Oxytocin is a cyclic nine-residue peptide; the medicinal form is made by chemical synthesis and is identical to the hormone stored in the posterior pituitary. The UK product information states that it stimulates the smooth muscle of the uterus, more powerfully towards the end of pregnancy, during labour and immediately afterwards, when receptors in the myometrium are increased. The receptor is G-protein coupled; activation triggers release of calcium from intracellular stores and so myometrial contraction. The product information also notes weak intrinsic antidiuretic activity of the kind associated with vasopressin.

Research areas

  • Obstetric medicine
  • Social neuroscience

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

Well characterised. The receptor has been cloned and expressed, and its pharmacology described in detail, including ligand binding, G-protein coupling, cholesterol-dependent binding affinity and inhibition by progesterone. The UK product information itself cites in-vitro work showing that prolonged exposure causes desensitisation, probably through down-regulation of binding sites.

Animal evidence

Studies in living non-human animals.

Extensive. Mice lacking the oxytocin receptor show pervasive social deficits but entirely normal parturition — a striking dissociation between the obstetric and behavioural roles of the same receptor.

Human observational evidence

Studies observing people without assigning an intervention.

Present. Systematic review of maternal plasma oxytocin during physiological childbirth, and observational work on oxytocin used during labour and neonatal outcomes.

Clinical-trial evidence

Studies assigning an intervention to human participants.

Extensive and of high quality within the obstetric indications, including multiple Cochrane reviews of its use in the third stage of labour. Outside those indications the trial evidence is largely negative: the definitive trial of intranasal oxytocin in autism, in 290 children and adolescents over 24 weeks, found no significant difference from placebo on social or cognitive outcomes.

Study limitations

  • The high-quality trial evidence is confined to obstetric use. Nothing in the UK licence supports social, behavioural, metabolic or wellbeing uses.
  • The intranasal route used in almost all behavioural research is a different route and formulation from the licensed intravenous product, and how much reaches the brain after intranasal dosing remains contested.
  • The behavioural literature is dominated by small single-dose laboratory-task studies with limited replication. The one large, long, well-powered trial was null.
  • Even within obstetrics, review authors note continuing uncertainty about comparative effects against other drug classes and about optimal regimens.
  • Studies associating the oxytocin receptor gene with behavioural traits are numerous but have well-documented replication problems.

UK regulatory context

Prescription-only medicine (UK)

A medicine that may lawfully be supplied in the UK only against a prescription from an appropriate practitioner.

Source: Oxytocin 10 IU/ml Concentrate for Solution for Infusion — Summary of Product Characteristics (opens medicines.org.uk in a new tab) (electronic Medicines Compendium)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

Oxytocin is a hospital-administered prescription-only medicine given under continuous obstetric monitoring, and its recognised harms follow from that setting: over-stimulation of the uterus with consequences for the fetus, and — because of the intrinsic antidiuretic activity — water intoxication with low blood sodium. The listed undesirable effects include lethargy, drowsiness, unconsciousness and seizures in the context of water intoxication. None of this is manageable outside clinical supervision. For non-obstetric uses there is no licensed product anywhere in the UK, no established safety dataset for repeated administration, and no regulator-assessed position on benefit and risk.

References