Ciprofloxacin side effects: what 91,238 FDA adverse event reports show
Drug class
Fluoroquinolone antibacterial
Who reports
91,238 reports · 83% serious · 9,259 with death outcome · 58% female
Used for
Ciprofloxacin is a fluoroquinolone antibacterial indicated in adults (18 years of age and older) with the following infections caused by designated, susceptible bacteria and in pediatric patients where indicated: • Skin and Skin Structure Infections ( Error! Hyperlink reference not valid.
What it is
Ciprofloxacin Tablets, USP are synthetic antimicrobial agents for oral administration. Ciprofloxacin hydrochloride, USP, a fluoroquinolone, is the monohydrochloride monohydrate salt of 1-cyclopropyl- 6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)- 3-quinolinecarboxylic acid.
Boxed warning
SERIOUS ADVERSE REACTIONS INCLUDING TENDINITIS, TENDON RUPTURE, PERIPHERAL NEUROPATHY, CENTRAL NERVOUS SYSTEM EFFECTS AND EXACERBATION OF MYASTHENIA GRAVIS • Fluoroquinolones, including ciprofloxacin, have been assoc.
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.
- 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. 1,171 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 |
|---|---|---|---|---|---|---|
| Musculoskeletal injury | 82 | 117.9 90.3–154.0ROR 118.0 · χ² 6,168 / p <1e-300 | 76.5 EB05 63.6 · IC025 +5.4 3/3 methods agree | Labeled (related wording) related wording | serious n=79 · 100% consumer | not reported in cached trials |
| Vaginal flatulence | 103 | 116.9 92.1–148.2ROR 117.0 · χ² 7,720 / p <1e-300 | 76.3 EB05 64.7 · IC025 +5.5 3/3 methods agree | Not in label — unassessed | serious n=103 · ♀ 100% (drug 58%) | not reported in cached trials |
| Tendon discomfort | 246 | 111.3 95.6–129.7ROR 111.6 · χ² 17,939 / p <1e-300 | 74.5 EB05 67.0 · IC025 +5.8 3/3 methods agree | Labeled (related wording) related wording | serious n=241 | not reported in cached trials |
| Tendon pain | 1,949 | 79.6 75.6–83.8ROR 81.3 · χ² 111,841 / p <1e-300 | 59.1 EB05 56.9 · IC025 +5.8 3/3 methods agree | Labeled (related wording) related wording | serious n=1,783 · 72% consumer | not reported in cached trials |
| Chronic kidney disease-mineral and bone disorder | 186 | 47.9 40.9–56.2ROR 48.0 · χ² 7,013 / p <1e-300 | 39.6 EB05 35.0 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious n=186 | not reported in cached trials |
| Tendon disorder | 1,100 | 46.5 43.6–49.6ROR 47.0 · χ² 40,566 / p <1e-300 | 38.7 EB05 36.8 · IC025 +5.2 3/3 methods agree | Labeled adverse reaction exact term | serious n=982 | not reported in cached trials |
| Hyperparathyroidism secondary | 399 | 42.9 38.6–47.7ROR 43.1 · χ² 13,687 / p <1e-300 | 36.2 EB05 33.3 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious n=399 | not reported in cached trials |
| Nephrogenic anaemia | 725 | 42.1 38.9–45.6ROR 42.4 · χ² 24,484 / p <1e-300 | 35.6 EB05 33.5 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious n=725 | not reported in cached trials |
| Dysbiosis | 115 | 38.4 31.5–46.8ROR 38.5 · χ² 3,549 / p <1e-300 | 32.8 EB05 28.1 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=115 | not reported in cached trials |
| Tendonitis | 2,198 | 37.7 36.1–39.5ROR 38.6 · χ² 67,360 / p <1e-300 | 32.5 EB05 31.3 · IC025 +4.9 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 25.5 | not reported in cached trials |
| Rebound acid hypersecretion | 431 | 37.5 33.9–41.5ROR 37.7 · χ² 13,097 / p <1e-300 | 32.2 EB05 29.8 · IC025 +4.8 3/3 methods agree | Not in label — unassessed | serious n=431 · 100% consumer | not reported in cached trials |
| Small fibre neuropathy | 90 | 32.2 25.8–40.2ROR 32.2 · χ² 2,354 / p <1e-300 | 28.2 EB05 23.6 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious n=89 · ♀ 0% (drug 58%) · 100% consumer | not reported in cached trials |
| Nasal oedema | 200 | 28.8 24.8–33.3ROR 28.8 · χ² 4,730 / p <1e-300 | 25.6 EB05 22.7 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=200 · ♀ 100% (drug 58%) · 100% clinician | not reported in cached trials |
| Pouchitis | 89 | 26.4 21.2–32.8ROR 26.4 · χ² 1,923 / p <1e-300 | 23.6 EB05 19.8 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=86 · ♀ 0% (drug 58%) | not reported in cached trials |
| Tendon rupture (torn tendon) | 1,254 | 25.8 24.4–27.4ROR 26.2 · χ² 26,851 / p <1e-300 | 23.3 EB05 22.2 · IC025 +4.4 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 16.7 | not reported in cached trials |
| Joint noise | 193 | 25.3 21.8–29.4ROR 25.4 · χ² 4,032 / p <1e-300 | 22.8 EB05 20.2 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=181 · 79% consumer | not reported in cached trials |
| Female genital tract fistula | 170 | 25.1 21.4–29.4ROR 25.1 · χ² 3,519 / p <1e-300 | 22.6 EB05 19.9 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=170 · ♀ 100% (drug 58%) | not reported in cached trials |
| Joint crepitation | 196 | 24.7 21.3–28.6ROR 24.8 · χ² 4,000 / p <1e-300 | 22.3 EB05 19.8 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=178 | not reported in cached trials |
| Tendon injury | 329 | 22.1 19.8–24.8ROR 22.2 · χ² 6,024 / p <1e-300 | 20.2 EB05 18.4 · IC025 +4.1 3/3 methods agree | Labeled (related wording) related wording | serious n=308 · 72% consumer | not reported in cached trials |
| Connective tissue disorder | 117 | 20.5 17.0–24.8ROR 20.5 · χ² 1,973 / p <1e-300 | 18.8 EB05 16.1 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=113 | not reported in cached trials |
| Chronic fatigue syndrome | 111 | 19.9 16.4–24.1ROR 19.9 · χ² 1,813 / p <1e-300 | 18.3 EB05 15.6 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=109 · 100% consumer | not reported in cached trials |
| Epicondylitis | 114 | 18.7 15.5–22.7ROR 18.8 · χ² 1,751 / p <1e-300 | 17.3 EB05 14.8 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=112 · 100% consumer | not reported in cached trials |
| End stage renal disease | 1,382 | 18.6 17.6–19.6ROR 18.8 · χ² 21,240 / p <1e-300 | 17.2 EB05 16.5 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious PRR 11.9 | not reported in cached trials |
| Fistula discharge | 89 | 17.3 13.9–21.4ROR 17.3 · χ² 1,252 / p 2e-274 | 16.0 EB05 13.4 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=85 | not reported in cached trials |
| Pseudomembranous colitis | 139 | 15.1 12.7–17.9ROR 15.1 · χ² 1,704 / p <1e-300 | 14.2 EB05 12.3 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious n=139 · 100% clinician | not reported in cached trials |
| Rectal abscess | 99 | 14.3 11.7–17.5ROR 14.3 · χ² 1,140 / p 3e-250 | 13.4 EB05 11.3 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=99 · ♀ 0% (drug 58%) | not reported in cached trials |
| Radiculopathy | 155 | 14.3 12.2–16.8ROR 14.3 · χ² 1,790 / p <1e-300 | 13.5 EB05 11.7 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=153 · ♀ 100% (drug 58%) | not reported in cached trials |
| Clostridium test positive | 127 | 14.2 11.8–16.9ROR 14.2 · χ² 1,449 / p <1e-300 | 13.3 EB05 11.4 · IC025 +3.4 3/3 methods agree | Lab value / disease marker | serious n=127 · 100% clinician | not reported in cached trials |
| Muscle rupture | 224 | 14.0 12.3–16.1ROR 14.1 · χ² 2,542 / p <1e-300 | 13.2 EB05 11.8 · IC025 +3.5 3/3 methods agree | Labeled (related wording) related wording | serious n=217 · ♀ 38% (drug 58%) | not reported in cached trials |
| Chronic kidney disease | 4,400 | 13.9 13.5–14.4ROR 14.6 · χ² 49,966 / p <1e-300 | 13.2 EB05 12.9 · IC025 +3.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 9.3 | not reported in cached trials |
| Proctitis | 158 | 13.7 11.6–16.0ROR 13.7 · χ² 1,737 / p <1e-300 | 12.9 EB05 11.3 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=158 · ♀ 78% (drug 58%) | not reported in cached trials |
| Plantar fasciitis | 184 | 13.2 11.4–15.4ROR 13.3 · χ² 1,955 / p <1e-300 | 12.5 EB05 11.0 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=176 · 72% consumer | not reported in cached trials |
| Clostridium difficile colitis | 566 | 12.9 11.8–14.0ROR 13.0 · χ² 5,864 / p <1e-300 | 12.2 EB05 11.4 · IC025 +3.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 8.6 · 90% clinician | not reported in cached trials |
| Weight bearing difficulty | 144 | 12.9 10.9–15.2ROR 12.9 · χ² 1,483 / p <1e-300 | 12.2 EB05 10.6 · IC025 +3.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=137 | not reported in cached trials |
| Tubulointerstitial nephritis | 960 | 12.4 11.6–13.2ROR 12.5 · χ² 9,508 / p <1e-300 | 11.8 EB05 11.2 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious PRR 8.2 | not reported in cached trials |
| Depersonalisation/derealisation disorder | 82 | 12.3 9.8–15.3ROR 12.3 · χ² 796 / p 2e-175 | 11.5 EB05 9.5 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=82 · 100% consumer | not reported in cached trials |
| Prostatitis | 154 | 12.2 10.4–14.4ROR 12.3 · χ² 1,497 / p <1e-300 | 11.6 EB05 10.1 · IC025 +3.2 3/3 methods agree | Likely indication confounding term in indications | serious n=138 · ♀ 0% (drug 58%) | not reported in cached trials |
| Pathogen resistance | 454 | 12.0 10.9–13.2ROR 12.1 · χ² 4,346 / p <1e-300 | 11.4 EB05 10.6 · IC025 +3.3 3/3 methods agree | Reporting / coding artifact | serious PRR 8.3 · 100% clinician | not reported in cached trials |
| Loss of employment | 152 | 12.0 10.2–14.1ROR 12.0 · χ² 1,447 / p <1e-300 | 11.4 EB05 9.9 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=149 · ♀ 100% (drug 58%) | not reported in cached trials |
| Anal fistula | 263 | 11.9 10.5–13.4ROR 11.9 · χ² 2,478 / p <1e-300 | 11.3 EB05 10.2 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=260 | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Ciprofloxacin as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).
- NCT03354598 — Oral Sulopenem-etzadroxil/Probenecid Versus Ciprofloxacin for Uncomplicated Urinary Tract Infection in Adult W (N=1671, PHASE3; 12 AE terms posted; arms: Sulopenem-etzadroxil/Probenecid; Ciprofloxacin)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
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 |
|---|---|---|---|---|---|---|
| Drug hypersensitivity | 5,772 | 7.0 6.8–7.2ROR 7.4 · χ² 29,115 / p <1e-300 | 6.8 EB05 6.7 · IC025 +2.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.6 · ♀ 82% (drug 58%) | not reported in cached trials |
| Pain | 5,706 | 2.1 2.1–2.2ROR 2.2 · χ² 3,544 / p <1e-300 | 2.1 EB05 2.1 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.1 | NCT03354598: 1/833 (0.1%) on Ciprofloxacin (serious AE) |
| Fatigue (tiredness) | 5,612 | 1.7 1.6–1.7ROR 1.7 · χ² 1,536 / p <1e-300 | 1.7 EB05 1.6 · IC025 +0.7 | Labeled — boxed warning synonym match | serious PRR 1.9 | not reported in cached trials |
| Nausea | 5,419 | 1.6 1.5–1.6ROR 1.6 · χ² 1,199 / p 6e-263 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.8 | not reported in cached trials |
| Diarrhoea (diarrhea) | 5,412 | 1.9 1.9–2.0ROR 2.0 · χ² 2,527 / p <1e-300 | 1.9 EB05 1.9 · IC025 +0.9 | Likely indication confounding term in indications; also in warnings | serious PRR 2.0 | NCT03354598: 1/827 (0.1%) on Ciprofloxacin (serious AE) |
| Arthralgia (joint pain) | 5,308 | 3.0 2.9–3.0ROR 3.1 · χ² 6,980 / p <1e-300 | 2.9 EB05 2.9 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.3 | not reported in cached trials |
| Drug ineffective (drug did not work) | 4,768 | 0.8 0.8–0.9ROR 0.8 · χ² 173 / p 1e-39 | 0.8 EB05 0.8 · IC025 -0.3 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.4 | not reported in cached trials |
| Acute kidney injury (sudden kidney damage) | 4,592 | 7.1 6.9–7.3ROR 7.4 · χ² 23,564 / p <1e-300 | 6.9 EB05 6.8 · IC025 +2.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.8 | not reported in cached trials |
| Chronic kidney disease | 4,400 | 13.9 13.5–14.4ROR 14.6 · χ² 49,966 / p <1e-300 | 13.2 EB05 12.9 · IC025 +3.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 9.3 | not reported in cached trials |
| Dyspnoea (shortness of breath) | 4,221 | 1.7 1.7–1.8ROR 1.8 · χ² 1,298 / p 1e-284 | 1.7 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 1.5 | not reported in cached trials |
| Off label use (used outside approved label) | 4,183 | 1.1 1.1–1.1ROR 1.1 · χ² 46 / p 7e-12 | 1.1 EB05 1.1 · IC025 +0.1 | Reporting / coding artifact | serious PRR 1.3 | not reported in cached trials |
| Pyrexia (fever) | 3,933 | 2.6 2.5–2.7ROR 2.7 · χ² 3,990 / p <1e-300 | 2.6 EB05 2.5 · IC025 +1.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.2 | not reported in cached trials |
| Anxiety | 3,856 | 3.1 3.0–3.2ROR 3.2 · χ² 5,606 / p <1e-300 | 3.1 EB05 3.0 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.9 | not reported in cached trials |
| Vomiting | 3,849 | 1.9 1.8–2.0ROR 1.9 · χ² 1,647 / p <1e-300 | 1.9 EB05 1.8 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 1.8 | not reported in cached trials |
| Headache | 3,737 | 1.4 1.3–1.4ROR 1.4 · χ² 389 / p 6e-87 | 1.4 EB05 1.3 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.7 | not reported in cached trials |
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.
- Vaginal flatulence — n=103, PRR 116.9
- Chronic kidney disease-mineral and bone disorder — n=186, PRR 47.9
- Hyperparathyroidism secondary — n=399, PRR 42.9
- Nephrogenic anaemia — n=725, PRR 42.1
- Dysbiosis — n=115, PRR 38.4
- Rebound acid hypersecretion — n=431, PRR 37.5
- Small fibre neuropathy — n=90, PRR 32.2
- Nasal oedema — n=200, PRR 28.8
- Pouchitis — n=89, PRR 26.4
- Joint noise — n=193, PRR 25.3
✓ A hand-written Bradford Hill causality assessment exists for this drug: Ciprofloxacin (fluoroquinolones) ↔ Tendon rupture / tendinitis.
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 Ciprofloxacin?
In FDA FAERS, the most frequently co-reported reaction terms for Ciprofloxacin are drug hypersensitivity, pain, fatigue, nausea, diarrhoea, arthralgia. 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 Ciprofloxacin have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: SERIOUS ADVERSE REACTIONS INCLUDING TENDINITIS, TENDON RUPTURE, PERIPHERAL NEUROPATHY, CENTRAL NERVOUS SYSTEM EFFECTS AND EXACERBATION OF MYASTHENIA GRAVIS • Fluoroquinolones, including ciprofloxacin, have been assoc.
Do FAERS signals prove that Ciprofloxacin 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 18414c5a-8153-44f7-b27a-90c290af0a23, effective 20260327; matched on
openfda.generic_name.exact:"CIPROFLOXACIN" AND openfda.product_type:"HUMAN PRESCRIPTION DRUG") - 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, 1,211 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 - ClinicalTrials.gov API v2 (query
CIPROFLOXACIN, results-bearing studies sorted by enrollment)
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.