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Oxytocin

Also known as Syntocinon, Pitocin

Approved medicine

Peptide hormone that causes uterine contractions and milk let down. Approved for use in labour and after birth; nasal use for social or sexual effects is experimental with mixed trial results.

Prescription medicine. Only a prescriber can decide whether a medicine suits you and at what dose. This page is information, not a recommendation.

Background

Oxytocin is a natural nine amino acid hormone made in the hypothalamus and released from the pituitary. It was the first peptide hormone to be synthesised, by Vincent du Vigneaud in 1953, work that earned the 1955 Nobel Prize in Chemistry. Synthetic oxytocin is sold as Syntocinon in Australia and Pitocin in the US.

How it is thought to work

It binds oxytocin receptors in the uterus, causing contractions, and in the breast, triggering milk let down. In the brain it influences social behaviour and bonding, which is why nasal sprays are being researched.

What is claimed, and the evidence

Claim	Evidence	Notes
Induction or strengthening of labour when medically indicated	Approved use	Approved indication given by IV infusion in hospital.
Control of bleeding after birth	Approved use	Approved postpartum indication.
Improved social functioning in autism (nasal spray)	Human trials Mixed results	A 2021 meta-analysis of 28 studies found benefit in social functioning; individual large trials have been mixed and it is not approved for this.
Better libido, orgasm, bonding or intimacy	No published evidence	Popular claims for nasal sprays; human evidence is limited and inconsistent.
Reduced anxiety, weight loss or 'love hormone' mood effects	No published evidence	Marketed claims; not established in trials.

Side effects

Effect	How often	Notes
Nausea and vomiting	Common	Listed maternal adverse reactions on the label.
Overly strong or prolonged contractions, uterine rupture Serious	Rare	Label: excessive dosage or hypersensitivity can cause uterine hypertonicity, spasm or rupture.
Water intoxication with seizures and coma Serious	Rare	Label reports maternal deaths from water intoxication with prolonged infusion.
Heart rhythm changes and blood pressure spikes Serious	Rare	Label lists arrhythmias, premature ventricular contractions and hypertensive episodes.
Anaphylaxis Serious	Rare	Listed on the label.
Fetal harm (slow heart rate, brain damage, death) during labour use Serious	Rare	Label lists fetal and neonatal adverse reactions linked to induced contractions.
Nasal discomfort, tiredness, irritability with nasal spray	Common	Most common in a meta-analysis of intranasal trials in autism, but not clearly more frequent than placebo.

Warnings

Labour use is hospital only, with continuous monitoring; the label warns of uterine rupture and fatal water intoxication.
Nasal oxytocin for social, sexual or mood effects is not approved and long term effects are not established.
Unapproved products are not assessed by the TGA for quality, safety or efficacy and may be contaminated, non-sterile, underdosed, overdosed or contain a different substance altogether.

Regulatory status

Australia: Approved (ARTG, Syntocinon injection) for obstetric use. Schedule 4.
United States: FDA approved (Pitocin) for induction and strengthening of labour and control of postpartum bleeding.

Sources

Also in Sexual health

From the VialOwl library, reviewed 26 September 2026. For education and general information. It is not medical advice and not a recommendation to use Oxytocin.