Oxytocin side effects: what 2,981 FDA adverse event reports show
Drug class
Oxytocic
Brand names
Pitocin
Who reports
2,981 reports · 88% serious · 150 with death outcome · 87% female
Used for
IMPORTANT NOTICE Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, Pitocin is not indicated for elective induction of labor.
What it is
DESCRIPTION Pitocin (oxytocin injection, USP) is a sterile, clear, colorless aqueous solution of synthetic oxytocin, for intravenous infusion or intramuscular injection. Pitocin is a nonapeptide found in pituitary extracts from mammals.
Boxed warning
IMPORTANT NOTICE Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, Pitocin is not indicated for elective induction of labor.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 55 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Premature delivery | 160 | 71.0 61.0–82.7ROR 75.0 · χ² 10,874 / p <1e-300 | 69.8 EB05 61.1 · IC025 +5.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 45.5 | no trial data cached |
| Caesarean section | 105 | 63.3 52.4–76.5ROR 65.6 · χ² 6,326 / p <1e-300 | 62.1 EB05 52.8 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious PRR 40.1 | no trial data cached |
| Premature baby | 206 | 48.3 42.3–55.1ROR 51.8 · χ² 9,443 / p <1e-300 | 47.8 EB05 42.5 · IC025 +5.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 31.3 · ♀ 52% (drug 87%) | no trial data cached |
| Exposure during pregnancy | 361 | 41.1 37.3–45.2ROR 46.6 · χ² 14,027 / p <1e-300 | 40.7 EB05 37.3 · IC025 +5.1 3/3 methods agree | Reporting / coding artifact | serious PRR 36.4 | no trial data cached |
| Foetal exposure during pregnancy | 443 | 38.5 35.4–42.0ROR 45.1 · χ² 16,138 / p <1e-300 | 38.3 EB05 35.4 · IC025 +5.0 3/3 methods agree | Reporting / coding artifact | serious PRR 25.1 · ♀ 43% (drug 87%) | no trial data cached |
| Maternal exposure during pregnancy | 432 | 34.6 31.7–37.8ROR 40.3 · χ² 14,054 / p <1e-300 | 34.4 EB05 31.8 · IC025 +4.9 3/3 methods agree | Reporting / coding artifact | serious PRR 25.2 · 90% clinician | no trial data cached |
| Drug exposure during pregnancy | 143 | 29.3 24.9–34.4ROR 30.7 · χ² 3,866 / p <1e-300 | 29.0 EB05 25.3 · IC025 +4.5 3/3 methods agree | Reporting / coding artifact | serious PRR 19.5 | no trial data cached |
| Hypothermia | 24 | 16.7 11.2–24.9ROR 16.8 · χ² 337 / p 1e-75 | 16.3 EB05 11.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 11.0 · 100% clinician | no trial data cached |
| Disseminated intravascular coagulation | 32 | 16.0 11.3–22.5ROR 16.1 · χ² 433 / p 1e-96 | 15.7 EB05 11.5 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious PRR 10.4 · 91% clinician | no trial data cached |
| Hypotonia | 16 | 11.2 6.9–18.3ROR 11.3 · χ² 139 / p 2e-32 | 10.0 EB05 6.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 8.4 | no trial data cached |
| Hypoxia (low oxygen) | 54 | 10.8 8.3–14.1ROR 11.0 · χ² 473 / p 4e-105 | 10.5 EB05 8.2 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 · 92% clinician | no trial data cached |
| Anaphylactic reaction (severe allergic reaction) | 66 | 8.5 6.7–10.7ROR 8.6 · χ² 427 / p 3e-95 | 8.1 EB05 6.6 · IC025 +2.6 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 5.6 | no trial data cached |
| Cyanosis (blue skin from low oxygen) | 18 | 8.0 5.1–12.7ROR 8.1 · χ² 104 / p 1e-24 | 7.0 EB05 4.5 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 5.5 | no trial data cached |
| Pregnancy | 22 | 7.7 5.0–11.6ROR 7.7 · χ² 121 / p 2e-28 | 6.8 EB05 4.7 · IC025 +2.0 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 7.0 · 90% clinician | no trial data cached |
| Pulmonary oedema | 47 | 7.4 5.6–9.8ROR 7.5 · χ² 253 / p 3e-57 | 7.0 EB05 5.4 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 · 93% clinician | no trial data cached |
| Status epilepticus | 11 | 6.8 3.8–12.3ROR 6.9 · χ² 49 / p 1e-12 | 5.5 EB05 3.2 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 | no trial data cached |
| Hypotension (low blood pressure) | 191 | 6.7 5.9–7.7ROR 7.1 · χ² 931 / p 1e-204 | 6.6 EB05 5.9 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 · 92% clinician | no trial data cached |
| Myoclonus | 11 | 6.5 3.6–11.7ROR 6.5 · χ² 46 / p 7e-12 | 5.2 EB05 3.1 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 | no trial data cached |
| Sinus tachycardia | 13 | 6.5 3.8–11.1ROR 6.5 · χ² 55 / p 7e-14 | 5.4 EB05 3.3 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Bronchospasm (airway tightening) | 13 | 6.4 3.7–11.0ROR 6.4 · χ² 54 / p 1e-13 | 5.3 EB05 3.3 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 4.6 | no trial data cached |
| Respiratory distress | 25 | 6.4 4.3–9.4ROR 6.4 · χ² 108 / p 1e-25 | 5.8 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 · ♀ 62% (drug 87%) | no trial data cached |
| Metabolic acidosis | 28 | 6.2 4.3–9.0ROR 6.3 · χ² 118 / p 1e-27 | 5.7 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 4.1 | no trial data cached |
| Tachycardia (fast heart rate) | 77 | 6.1 4.9–7.6ROR 6.2 · χ² 324 / p 9e-73 | 5.9 EB05 4.9 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.3 · 94% clinician | no trial data cached |
| Pulmonary hypertension | 18 | 6.1 3.8–9.6ROR 6.1 · χ² 71 / p 2e-17 | 5.3 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Paraesthesia oral | 12 | 5.9 3.3–10.3ROR 5.9 · χ² 44 / p 2e-11 | 4.9 EB05 3.0 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Anaphylactic shock | 21 | 5.8 3.8–8.8ROR 5.8 · χ² 78 / p 5e-19 | 5.2 EB05 3.6 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Respiratory depression | 10 | 5.7 3.1–10.7ROR 5.8 · χ² 35 / p 2e-9 | 4.6 EB05 2.7 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Generalised tonic-clonic seizure | 13 | 5.6 3.2–9.6ROR 5.6 · χ² 45 / p 1e-11 | 4.7 EB05 3.0 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 3.7 | no trial data cached |
| Ejection fraction decreased | 12 | 5.4 3.1–9.5ROR 5.4 · χ² 39 / p 2e-10 | 4.6 EB05 2.8 · IC025 +1.2 3/3 methods agree | Lab value / disease marker | serious PRR 3.9 | no trial data cached |
| Circulatory collapse | 13 | 5.3 3.1–9.2ROR 5.4 · χ² 42 / p 5e-11 | 4.6 EB05 2.8 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 3.2 | no trial data cached |
| Vaginal haemorrhage | 32 | 5.3 3.7–7.5ROR 5.3 · χ² 107 / p 2e-25 | 4.9 EB05 3.7 · IC025 +1.7 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 7.3 · 90% clinician | no trial data cached |
| Tachypnoea | 10 | 5.2 2.8–9.6ROR 5.2 · χ² 30 / p 2e-8 | 4.3 EB05 2.5 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 3.5 | no trial data cached |
| Contraindicated product administered | 22 | 5.1 3.4–7.8ROR 5.2 · χ² 69 / p 5e-17 | 4.7 EB05 3.3 · IC025 +1.5 3/3 methods agree | Reporting / coding artifact | serious PRR 4.2 | no trial data cached |
| Oxygen saturation decreased | 37 | 4.7 3.4–6.4ROR 4.7 · χ² 103 / p 2e-24 | 4.4 EB05 3.4 · IC025 +1.6 3/3 methods agree | Lab value / disease marker | serious PRR 3.3 · 91% clinician | no trial data cached |
| Proteinuria | 12 | 4.5 2.5–7.9ROR 4.5 · χ² 29 / p 4e-8 | 3.9 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 3.3 | no trial data cached |
| Hyponatraemia (low sodium) | 35 | 4.4 3.2–6.1ROR 4.4 · χ² 88 / p 3e-21 | 4.2 EB05 3.1 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 · 100% clinician | no trial data cached |
| Acute respiratory distress syndrome | 10 | 4.0 2.1–7.4ROR 4.0 · χ² 19 / p 5e-6 | 3.4 EB05 2.0 · IC025 +0.7 3/3 methods agree | Not in label — unassessed | serious PRR 2.6 | no trial data cached |
| Bradycardia (slow heart rate) | 30 | 4.0 2.8–5.7ROR 4.0 · χ² 64 / p 7e-16 | 3.8 EB05 2.8 · IC025 +1.3 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 2.5 · 97% clinician | no trial data cached |
| Aphasia (loss of speech) | 17 | 3.9 2.5–6.3ROR 4.0 · χ² 35 / p 2e-9 | 3.6 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Haemoglobin decreased | 56 | 3.8 3.0–5.0ROR 3.9 · χ² 115 / p 5e-27 | 3.7 EB05 3.0 · IC025 +1.5 3/3 methods agree | Lab value / disease marker | serious PRR 2.8 | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Foetal exposure during pregnancy | 443 | 38.5 35.4–42.0ROR 45.1 · χ² 16,138 / p <1e-300 | 38.3 EB05 35.4 · IC025 +5.0 3/3 methods agree | Reporting / coding artifact | serious PRR 25.1 · ♀ 43% (drug 87%) | no trial data cached |
| Maternal exposure during pregnancy | 432 | 34.6 31.7–37.8ROR 40.3 · χ² 14,054 / p <1e-300 | 34.4 EB05 31.8 · IC025 +4.9 3/3 methods agree | Reporting / coding artifact | serious PRR 25.2 · 90% clinician | no trial data cached |
| Exposure during pregnancy | 361 | 41.1 37.3–45.2ROR 46.6 · χ² 14,027 / p <1e-300 | 40.7 EB05 37.3 · IC025 +5.1 3/3 methods agree | Reporting / coding artifact | serious PRR 36.4 | no trial data cached |
| Premature baby | 206 | 48.3 42.3–55.1ROR 51.8 · χ² 9,443 / p <1e-300 | 47.8 EB05 42.5 · IC025 +5.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 31.3 · ♀ 52% (drug 87%) | no trial data cached |
| Hypotension (low blood pressure) | 191 | 6.7 5.9–7.7ROR 7.1 · χ² 931 / p 1e-204 | 6.6 EB05 5.9 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 · 92% clinician | no trial data cached |
| Premature delivery | 160 | 71.0 61.0–82.7ROR 75.0 · χ² 10,874 / p <1e-300 | 69.8 EB05 61.1 · IC025 +5.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 45.5 | no trial data cached |
| Drug exposure during pregnancy | 143 | 29.3 24.9–34.4ROR 30.7 · χ² 3,866 / p <1e-300 | 29.0 EB05 25.3 · IC025 +4.5 3/3 methods agree | Reporting / coding artifact | serious PRR 19.5 | no trial data cached |
| Caesarean section | 105 | 63.3 52.4–76.5ROR 65.6 · χ² 6,326 / p <1e-300 | 62.1 EB05 52.8 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious PRR 40.1 | no trial data cached |
| Tachycardia (fast heart rate) | 77 | 6.1 4.9–7.6ROR 6.2 · χ² 324 / p 9e-73 | 5.9 EB05 4.9 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.3 · 94% clinician | no trial data cached |
| Anaphylactic reaction (severe allergic reaction) | 66 | 8.5 6.7–10.7ROR 8.6 · χ² 427 / p 3e-95 | 8.1 EB05 6.6 · IC025 +2.6 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 5.6 | no trial data cached |
| Haemoglobin decreased | 56 | 3.8 3.0–5.0ROR 3.9 · χ² 115 / p 5e-27 | 3.7 EB05 3.0 · IC025 +1.5 3/3 methods agree | Lab value / disease marker | serious PRR 2.8 | no trial data cached |
| Hypoxia (low oxygen) | 54 | 10.8 8.3–14.1ROR 11.0 · χ² 473 / p 4e-105 | 10.5 EB05 8.2 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 · 92% clinician | no trial data cached |
| Pulmonary oedema | 47 | 7.4 5.6–9.8ROR 7.5 · χ² 253 / p 3e-57 | 7.0 EB05 5.4 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 · 93% clinician | no trial data cached |
| Haemorrhage | 45 | 3.0 2.3–4.0ROR 3.1 · χ² 59 / p 7e-15 | 3.0 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 2.2 | no trial data cached |
| Cardiac arrest (heart stopping) | 43 | 3.7 2.7–4.9ROR 3.7 · χ² 80 / p 2e-19 | 3.5 EB05 2.7 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 2.4 · 92% clinician | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Caesarean section — n=105, PRR 63.3
- Hypothermia — n=24, PRR 16.7
- Disseminated intravascular coagulation — n=32, PRR 16.0
- Hypoxia — n=54, PRR 10.8
- Pulmonary oedema — n=47, PRR 7.4
- Hypotension — n=191, PRR 6.7
- Respiratory distress — n=25, PRR 6.4
- Metabolic acidosis — n=28, PRR 6.2
- Tachycardia — n=77, PRR 6.1
- Anaphylactic shock — n=21, PRR 5.8
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Oxytocin?
In FDA FAERS, the most frequently co-reported reaction terms for Oxytocin are premature baby, hypotension, premature delivery, caesarean section, tachycardia, anaphylactic reaction. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Oxytocin have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: IMPORTANT NOTICE Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, Pitocin is not indicated for elective induction of labor.
Do FAERS signals prove that Oxytocin causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 6d4b2c25-2e5d-49b5-93bc-2ae8a20916d1, effective 20260506; matched on
openfda.generic_name.exact:"OXYTOCIN") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 95 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.