Mifepristone side effects: what 4,695 FDA adverse event reports show
Drug class
Progestin Antagonist
Who reports
4,695 reports · 61% serious · 346 with death outcome · 84% female
Used for
Mifepristone Tablets, 200 mg is indicated, in a regimen with misoprostol, for the medical termination of intrauterine pregnancy through 70 days gestation. Mifepristone Tablets, 200 mg is a progestin antagonist indicated, in a regimen with misoprostol, for the medical termination of intrauterine pregnancy through 70 days gestation. ( 1 )
What it is
Mifepristone tablets each contain 200 mg of mifepristone, a synthetic steroid with antiprogestational effects. The tablets are light yellow coloured, round, biconvex, debossed with “CC12” on one side, plain on other side and free from physical defects and are intended for oral administration only.
Boxed warning
SERIOUS AND SOMETIMES FATAL INFECTIONS OR BLEEDING Serious and sometimes fatal infections and bleeding occur very rarely following spontaneous, surgical, and medical abortions, including following Mifepristone Tablets, 200 mg use. No causal relationship between the use of Mifepristone Tablets, 200 mg and misoprostol and these events has been established.
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.
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- 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.
- 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. 192 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 |
|---|---|---|---|---|---|---|
| Blood potassium decreased | 453 | 68.3 62.5–74.6ROR 75.4 · χ² 29,537 / p <1e-300 | 67.0 EB05 62.0 · IC025 +5.8 3/3 methods agree | Lab value / disease marker | serious PRR 61.7 · 80% consumer | no trial data cached |
| Blood thyroid stimulating hormone increased | 67 | 32.6 25.7–41.4ROR 33.1 · χ² 2,009 / p <1e-300 | 32.1 EB05 26.2 · IC025 +4.3 3/3 methods agree | Lab value / disease marker | serious n=31 · 70% consumer | no trial data cached |
| Pregnancy | 118 | 26.2 21.9–31.3ROR 26.8 · χ² 2,820 / p <1e-300 | 26.0 EB05 22.3 · IC025 +4.3 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 3.9 · 100% clinician | no trial data cached |
| Abortion induced | 54 | 25.7 19.7–33.6ROR 26.0 · χ² 1,252 / p 2e-274 | 25.4 EB05 20.2 · IC025 +3.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 21.8 · 98% clinician | no trial data cached |
| Blood glucose decreased | 274 | 25.5 22.7–28.6ROR 27.0 · χ² 6,410 / p <1e-300 | 25.3 EB05 22.9 · IC025 +4.4 3/3 methods agree | Lab value / disease marker | serious PRR 34.7 · 89% consumer | no trial data cached |
| Blood glucose fluctuation | 62 | 25.3 19.8–32.4ROR 25.6 · χ² 1,417 / p <1e-300 | 25.0 EB05 20.2 · IC025 +4.0 3/3 methods agree | Lab value / disease marker | serious n=48 · 83% consumer | no trial data cached |
| Blood potassium increased | 90 | 24.9 20.3–30.6ROR 25.4 · χ² 2,031 / p <1e-300 | 24.7 EB05 20.7 · IC025 +4.1 3/3 methods agree | Lab value / disease marker | serious PRR 22.5 · 82% consumer | no trial data cached |
| Vaginal haemorrhage | 228 | 24.0 21.2–27.3ROR 25.2 · χ² 4,994 / p <1e-300 | 23.9 EB05 21.4 · IC025 +4.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 31.8 | no trial data cached |
| Amenorrhoea (missed periods) | 72 | 19.3 15.4–24.3ROR 19.6 · χ² 1,229 / p 1e-269 | 19.2 EB05 15.7 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious PRR 20.7 · 82% consumer | no trial data cached |
| Glomerular filtration rate decreased | 48 | 17.8 13.4–23.5ROR 17.9 · χ² 740 / p 3e-163 | 17.6 EB05 13.7 · IC025 +3.4 3/3 methods agree | Lab value / disease marker | serious PRR 10.3 | no trial data cached |
| Vaginal discharge | 39 | 17.4 12.7–23.8ROR 17.5 · χ² 584 / p 2e-129 | 17.2 EB05 13.0 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=16 · 75% consumer | no trial data cached |
| Haemorrhage | 361 | 15.5 14.0–17.1ROR 16.7 · χ² 4,879 / p <1e-300 | 15.4 EB05 14.1 · IC025 +3.7 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 7.2 · 95% clinician | no trial data cached |
| Dizziness postural | 25 | 11.7 7.9–17.2ROR 11.7 · χ² 232 / p 9e-53 | 10.9 EB05 7.5 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious n=14 · 84% consumer | no trial data cached |
| Hypokalaemia (low potassium) | 119 | 11.6 9.7–13.9ROR 11.9 · χ² 1,142 / p 1e-250 | 11.5 EB05 9.8 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious PRR 9.5 | no trial data cached |
| Glycosylated haemoglobin increased | 65 | 11.5 9.1–14.7ROR 11.7 · χ² 615 / p 5e-136 | 11.3 EB05 9.1 · IC025 +3.0 3/3 methods agree | Lab value / disease marker | serious PRR 15.1 · 84% consumer | no trial data cached |
| Hypoglycaemia (low blood sugar) | 114 | 10.5 8.8–12.6ROR 10.7 · χ² 971 / p 1e-213 | 10.3 EB05 8.8 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 8.6 · 87% consumer | no trial data cached |
| Blood pressure increased | 346 | 10.1 9.1–11.2ROR 10.8 · χ² 2,844 / p <1e-300 | 10.0 EB05 9.2 · IC025 +3.1 3/3 methods agree | Lab value / disease marker | serious PRR 9.7 · 83% consumer | no trial data cached |
| Adrenal insufficiency | 25 | 9.3 6.3–13.8ROR 9.4 · χ² 178 / p 8e-41 | 8.5 EB05 5.9 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.1 | no trial data cached |
| Ovarian cyst | 20 | 8.9 5.7–13.8ROR 8.9 · χ² 132 / p 7e-31 | 7.8 EB05 5.2 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Oedema | 106 | 8.8 7.3–10.6ROR 8.9 · χ² 721 / p 4e-159 | 8.5 EB05 7.2 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.3 · 75% consumer | no trial data cached |
| Fluid retention | 95 | 8.4 6.8–10.2ROR 8.5 · χ² 608 / p 1e-134 | 8.1 EB05 6.8 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 8.6 · 91% consumer | no trial data cached |
| Blood pressure decreased | 121 | 8.2 6.8–9.7ROR 8.3 · χ² 754 / p 3e-166 | 8.0 EB05 6.8 · IC025 +2.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 7.1 · 88% consumer | no trial data cached |
| Hypophagia | 46 | 8.1 6.1–10.8ROR 8.2 · χ² 279 / p 5e-63 | 7.6 EB05 5.9 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 · 84% consumer | no trial data cached |
| Retching | 38 | 8.0 5.8–11.0ROR 8.0 · χ² 225 / p 3e-51 | 7.4 EB05 5.6 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 10.9 · ♀ 63% (drug 84%) · 74% consumer | no trial data cached |
| Nocturia (night-time urination) | 21 | 7.8 5.1–11.9ROR 7.8 · χ² 117 / p 2e-27 | 6.8 EB05 4.6 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.1 · 90% consumer | no trial data cached |
| Hypothyroidism | 55 | 7.7 5.9–10.0ROR 7.8 · χ² 315 / p 8e-71 | 7.3 EB05 5.8 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 · 76% consumer | no trial data cached |
| Hypertensive crisis | 19 | 7.6 4.9–11.9ROR 7.6 · χ² 102 / p 2e-24 | 6.6 EB05 4.4 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 | no trial data cached |
| Blood triglycerides increased | 30 | 7.6 5.3–10.8ROR 7.6 · χ² 164 / p 6e-38 | 6.9 EB05 5.0 · IC025 +2.2 3/3 methods agree | Lab value / disease marker | serious PRR 5.2 · 83% consumer | no trial data cached |
| Oedema peripheral (swelling of legs/feet) | 202 | 7.4 6.5–8.5ROR 7.7 · χ² 1,113 / p 2e-244 | 7.3 EB05 6.5 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.4 · 86% consumer | no trial data cached |
| Peripheral swelling | 253 | 7.4 6.5–8.3ROR 7.7 · χ² 1,395 / p <1e-300 | 7.3 EB05 6.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 · 87% consumer | no trial data cached |
| Blood glucose increased | 311 | 7.4 6.6–8.2ROR 7.8 · χ² 1,713 / p <1e-300 | 7.3 EB05 6.6 · IC025 +2.7 3/3 methods agree | Lab value / disease marker | serious PRR 12.2 · 86% consumer | no trial data cached |
| Menorrhagia (heavy periods) | 31 | 7.0 4.9–9.9ROR 7.0 · χ² 152 / p 3e-35 | 6.4 EB05 4.7 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.1 | no trial data cached |
| Pollakiuria (frequent urination) | 62 | 6.7 5.2–8.5ROR 6.7 · χ² 293 / p 7e-66 | 6.4 EB05 5.1 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 · 92% consumer | no trial data cached |
| Hypersomnia | 41 | 6.4 4.7–8.7ROR 6.5 · χ² 182 / p 1e-41 | 6.0 EB05 4.6 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 · 88% consumer | no trial data cached |
| International normalised ratio increased | 40 | 6.2 4.6–8.5ROR 6.3 · χ² 170 / p 4e-39 | 5.8 EB05 4.4 · IC025 +2.0 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.4 · 87% consumer | no trial data cached |
| Liver injury | 33 | 6.1 4.3–8.6ROR 6.1 · χ² 136 / p 1e-31 | 5.7 EB05 4.2 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 5.9 · 100% clinician | no trial data cached |
| Feeling jittery | 26 | 6.1 4.1–8.9ROR 6.1 · χ² 105 / p 5e-25 | 5.5 EB05 4.0 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious n=10 · 85% consumer | no trial data cached |
| Thirst | 23 | 5.8 3.8–8.7ROR 5.8 · χ² 86 / p 1e-20 | 5.2 EB05 3.6 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 4.4 · 86% consumer | no trial data cached |
| Blood iron decreased | 15 | 5.7 3.4–9.4ROR 5.7 · χ² 53 / p 1e-13 | 4.9 EB05 3.2 · IC025 +1.4 3/3 methods agree | Lab value / disease marker | serious PRR 4.8 | no trial data cached |
| Decreased appetite (loss of appetite) | 277 | 5.3 4.8–6.0ROR 5.6 · χ² 984 / p 3e-216 | 5.3 EB05 4.8 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 · 89% consumer | 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 |
|---|---|---|---|---|---|---|
| Nausea | 794 | 4.5 4.2–4.8ROR 5.2 · χ² 2,238 / p <1e-300 | 4.5 EB05 4.2 · IC025 +2.0 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 4.9 · 80% consumer | no trial data cached |
| Fatigue (tiredness) | 695 | 4.0 3.7–4.3ROR 4.5 · χ² 1,618 / p <1e-300 | 4.0 EB05 3.7 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 · 85% consumer | no trial data cached |
| Blood potassium decreased | 453 | 68.3 62.5–74.6ROR 75.4 · χ² 29,537 / p <1e-300 | 67.0 EB05 62.0 · IC025 +5.8 3/3 methods agree | Lab value / disease marker | serious PRR 61.7 · 80% consumer | no trial data cached |
| Vomiting | 435 | 4.1 3.8–4.5ROR 4.5 · χ² 1,058 / p 2e-232 | 4.1 EB05 3.8 · IC025 +1.9 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 3.9 · 74% consumer | no trial data cached |
| Dizziness | 401 | 3.6 3.3–4.0ROR 3.8 · χ² 768 / p 3e-169 | 3.6 EB05 3.3 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.7 · 78% consumer | no trial data cached |
| Headache | 384 | 2.7 2.5–3.0ROR 2.9 · χ² 435 / p 6e-97 | 2.7 EB05 2.5 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.2 · 85% consumer | no trial data cached |
| Haemorrhage | 361 | 15.5 14.0–17.1ROR 16.7 · χ² 4,879 / p <1e-300 | 15.4 EB05 14.1 · IC025 +3.7 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 7.2 · 95% clinician | no trial data cached |
| Blood pressure increased | 346 | 10.1 9.1–11.2ROR 10.8 · χ² 2,844 / p <1e-300 | 10.0 EB05 9.2 · IC025 +3.1 3/3 methods agree | Lab value / disease marker | serious PRR 9.7 · 83% consumer | no trial data cached |
| Blood glucose increased | 311 | 7.4 6.6–8.2ROR 7.8 · χ² 1,713 / p <1e-300 | 7.3 EB05 6.6 · IC025 +2.7 3/3 methods agree | Lab value / disease marker | serious PRR 12.2 · 86% consumer | no trial data cached |
| Asthenia (weakness) | 283 | 3.4 3.0–3.8ROR 3.5 · χ² 476 / p 1e-105 | 3.3 EB05 3.0 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 3.5 · 82% consumer | no trial data cached |
| Pain | 280 | 2.0 1.8–2.3ROR 2.1 · χ² 150 / p 8e-35 | 2.0 EB05 1.8 · IC025 +0.8 | Labeled — boxed warning exact term | serious PRR 1.8 | no trial data cached |
| Decreased appetite (loss of appetite) | 277 | 5.3 4.8–6.0ROR 5.6 · χ² 984 / p 3e-216 | 5.3 EB05 4.8 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 · 89% consumer | no trial data cached |
| Blood glucose decreased | 274 | 25.5 22.7–28.6ROR 27.0 · χ² 6,410 / p <1e-300 | 25.3 EB05 22.9 · IC025 +4.4 3/3 methods agree | Lab value / disease marker | serious PRR 34.7 · 89% consumer | no trial data cached |
| Peripheral swelling | 253 | 7.4 6.5–8.3ROR 7.7 · χ² 1,395 / p <1e-300 | 7.3 EB05 6.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 · 87% consumer | no trial data cached |
| Arthralgia (joint pain) | 233 | 2.5 2.2–2.8ROR 2.6 · χ² 215 / p 7e-49 | 2.5 EB05 2.2 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 2.7 · 88% consumer | 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.
- Amenorrhoea — n=72, PRR 19.3
- Vaginal discharge — n=39, PRR 17.4
- Dizziness postural — n=25, PRR 11.7
- Hypokalaemia — n=119, PRR 11.6
- Hypoglycaemia — n=114, PRR 10.5
- Ovarian cyst — n=20, PRR 8.9
- Fluid retention — n=95, PRR 8.4
- Hypophagia — n=46, PRR 8.1
- Retching — n=38, PRR 8.0
- Nocturia — n=21, PRR 7.8
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 Mifepristone?
In FDA FAERS, the most frequently co-reported reaction terms for Mifepristone are nausea, fatigue, blood potassium decreased, vomiting, dizziness, headache. 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 Mifepristone have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: SERIOUS AND SOMETIMES FATAL INFECTIONS OR BLEEDING Serious and sometimes fatal infections and bleeding occur very rarely following spontaneous, surgical, and medical abortions, including following Mifepristone Tablets, 200 mg use. No causal relationship between the use of Mifepristone Tablets, 200 mg and misoprostol and these events has been established.
Do FAERS signals prove that Mifepristone 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 839d7a7d-de19-42bd-8810-132b3c2a5daf, effective 20251112; matched on
openfda.generic_name.exact:"MIFEPRISTONE") - 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, 232 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.