Uterotonic Pregnancy: Based on wide experience, its chemical structure and pharmacological properties, oxytocin is not expected to present a risk of foetal abnormalities when used as indicated; no standard reproductive performance studies are available. Oxytocin may be found in small quantities in breast milk but is not expected to cause harmful effects in the newborn as it is rapidly inactivated in the alimentary tract. Fertility: not applicable because of the targeted indications.

Oxytocin

Brand names: Syntocinon

Oxytocin is a synthetic form of the posterior pituitary hormone used in obstetrics to induce or augment labour and to prevent or treat postpartum haemorrhage.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Induction or enhancement of labour: initial infusion rate 1 to 4 milliunits/minute (2 to 8 drops/minute). Increase gradually at intervals not shorter than 20 minutes, in increments of not more than 1-2 milliunits/minute, until a contraction pattern similar to that of normal labour is established. Recommended dilution for drip infusion: 5 IU oxytocin added to 500 ml of a physiological electrolyte solution (such as sodium chloride 0.9%); 5% dextrose may be used as the diluent for patients in whom infusion of sodium chloride must be avoided.

Route: Intravenous infusion only — IV drip infusion or, preferably, by variable-speed infusion pump. Must NEVER be given by IV bolus injection (may cause acute short-lasting hypotension with flushing and reflex tachycardia).

Frequency: Continuous infusion, rate titrated to uterine activity. Once an adequate level of uterine activity is attained (aiming for 3 to 4 contractions every 10 minutes) the infusion rate can often be reduced. Discontinue immediately if uterine hyperactivity and/or foetal distress occurs.

Max: Recommended maximum rate 20 milliunits/minute (40 drops/minute) for induction/enhancement of labour. In pregnancy near term this can often be achieved with an infusion of less than 10 milliunits/minute (20 drops/minute). If, in women at or near term, regular contractions are not established after a total amount of 5 IU, the attempt to induce labour should be ceased; it may be repeated the following day starting again from a rate of 1 to 4 milliunits/minute.

Other indications (all as IV infusion, 5 IU diluted in physiological electrolyte solution and given over 5 minutes): incomplete, inevitable or missed abortion — 5 IU, if necessary followed by IV infusion at 20 to 40 milliunits/minute; caesarean section — 5 IU immediately after delivery; prevention of postpartum uterine haemorrhage — usual dose 5 IU after delivery of the placenta; treatment of postpartum uterine haemorrhage — 5 IU, followed in severe cases by IV infusion of a solution containing 5 to 20 IU of oxytocin in 500 ml of an electrolyte-containing diluent, run at the rate necessary to control uterine atony. Oxytocin should not be started for 6 hours following administration of vaginal prostaglandins. Where higher rates are needed (e.g. foetal death in utero, induction at an earlier stage of pregnancy) a more concentrated solution, e.g. 10 IU in 500 ml, is advisable. With motor-driven pumps delivering smaller volumes, the concentration must be calculated according to the pump specifications. Turn the bottle/bag upside down several times before use to ensure even mixing. Frequency, strength and duration of contractions and the foetal heart rate must be carefully monitored throughout the infusion. In women given oxytocin for induction or enhancement of labour, the infusion should be continued at an increased rate during the third stage of labour and for the next few hours thereafter. Special populations: no studies have been performed in renally impaired, hepatically impaired, paediatric or elderly (65 years and over) patients. NOTE ON SOURCE: the fetched §4.4 and §4.8 extracts were truncated at the source-fetch limit, and §4.5 (interactions) was not retrieved in this bundle — the lists below are therefore partial.

Dose adjustments

Renal

No studies have been performed in renally impaired patients (nor in hepatically impaired patients) — no dose adjustment is stated.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Hypertonic uterine contractions, mechanical obstruction to delivery, foetal distress
Any condition in which spontaneous labour is inadvisable and/or vaginal delivery is contraindicated: significant cephalopelvic disproportion; foetal malpresentation; placenta praevia and vasa praevia; placental abruption; cord presentation or prolapse
Overdistension or impaired resistance of the uterus to rupture (e.g. multiple pregnancy, polyhydramnios, grand multiparity), or a uterine scar resulting from major surgery including classical caesarean section
Should not be used for prolonged periods in oxytocin-resistant uterine inertia, severe pre-eclamptic toxaemia or severe cardiovascular disorders
Must not be administered within 6 hours after vaginal prostaglandins have been given

Side effects

Uterine overstimulation from excessive doses — uterine spasm, hypertonicity, tetanic contractions, soft tissue damage or rupture of the uterus; foetal distress, asphyxia and death
Acute short-lasting hypotension with flushing and reflex tachycardia after rapid IV bolus injection of doses amounting to several IU; may cause myocardial ischaemia in patients with pre-existing cardiovascular disease
QTc prolongation after rapid IV bolus injection of doses amounting to several IU
Water intoxication with maternal and neonatal hyponatraemia after high doses with large amounts of electrolyte-free fluid over a prolonged period (headache, anorexia, nausea, vomiting, abdominal pain; lethargy, drowsiness, unconsciousness, grand-mal type seizures; low blood electrolyte concentration)
Fluid overload leading to a haemodynamic form of acute pulmonary oedema without hyponatraemia
Increased risk of postpartum disseminated intravascular coagulation (DIC) in rare circumstances

Interactions

Vaginal prostaglandins — oxytocin must not be administered within 6 hours after they have been given (§4.3 / §4.2)
Drugs known to prolong the QTc interval — give oxytocin with caution, as with patients with known long QT syndrome or related symptoms (§4.4)
Full §4.5 interaction section was not retrieved in this source bundle

Clinical monograph

How it works

It binds uterine oxytocin receptors to increase the frequency and force of myometrial contractions, with receptor sensitivity rising towards term.

Prescribing in practice

Excessive dosing or infusion rate can cause uterine hyperstimulation with fetal distress or uterine rupture, so labour induction/augmentation must be titrated against contractions and continuous fetal monitoring.
Prolonged high-dose infusion with large volumes of electrolyte-free fluid can cause water intoxication and hyponatraemia owing to its antidiuretic effect.
Rapid intravenous bolus can cause hypotension, tachycardia, and arrhythmia, so it is given by slow injection or controlled infusion.

Monitoring

Monitor uterine activity and continuous fetal heart rate during labour, together with maternal blood pressure, pulse, and fluid balance.

Counselling the patient

Explain to the woman that this medicine strengthens contractions to help labour or to reduce bleeding after delivery.
The infusion is closely controlled and the baby's heart rate is monitored throughout.
Tell the team if contractions feel excessively strong or unrelenting.

Evidence & guidelines

A cornerstone of NICE-endorsed labour management and active management of the third stage of labour to reduce postpartum haemorrhage.

Reference: RCOG Induction of Labour Guideline; WHO PPH Prevention Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Pathways