Nitrofurantoin side effects: what 16,394 FDA adverse event reports show
Drug class
Nitrofuran antibacterial
Who reports
16,394 reports · 80% serious · 1,028 with death outcome · 84% female
Used for
Nitrofurantoin oral suspension is indicated in adults and pediatric patients 1 month of age and older for the treatment of urinary tract infections due to susceptible strains of Escherichia coli, Enterococcus species , Staphylococcus aureus, Klebsiella species and Enterobacter species.
What it is
Nitrofurantoin oral suspension, USP contains nitrofurantoin, a synthetic nitrofuran antibacterial agent specific for urinary tract infections.
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
What the badges mean
- 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. 1,141 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 |
|---|---|---|---|---|---|---|
| Heart sounds | 57 | 1,843.2 1,226.9–2,769.1ROR 1,849.6 · χ² 41,890 / p <1e-300 | 598.0 EB05 478.7 · IC025 +6.2 3/3 methods agree | Not in label — unassessed | serious n=57 | not reported in cached trials |
| Urine leukocyte esterase | 13 | 356.4 192.6–659.5ROR 356.7 · χ² 3,320 / p <1e-300 | 197.7 EB05 123.0 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Prolonged expiration | 57 | 352.4 262.8–472.5ROR 353.6 · χ² 15,337 / p <1e-300 | 252.3 EB05 202.0 · IC025 +5.9 3/3 methods agree | Not in label — unassessed | serious n=57 | not reported in cached trials |
| Steroid dependence | 121 | 212.5 175.4–257.5ROR 214.1 · χ² 21,621 / p <1e-300 | 177.0 EB05 152.1 · IC025 +6.4 3/3 methods agree | Not in label — unassessed | serious n=121 · ♀ 17% (drug 84%) · 92% clinician | not reported in cached trials |
| Catarrh | 124 | 207.4 171.6–250.6ROR 209.0 · χ² 21,697 / p <1e-300 | 173.5 EB05 149.4 · IC025 +6.4 3/3 methods agree | Not in label — unassessed | serious n=124 · ♀ 18% (drug 84%) · 93% clinician | not reported in cached trials |
| Burns second degree | 126 | 99.3 82.8–118.9ROR 100.0 · χ² 11,271 / p <1e-300 | 90.9 EB05 78.3 · IC025 +5.8 3/3 methods agree | Not in label — unassessed | serious n=126 · ♀ 18% (drug 84%) · 92% clinician | not reported in cached trials |
| Sensitisation | 41 | 72.3 52.8–99.0ROR 72.5 · χ² 2,660 / p <1e-300 | 66.4 EB05 51.0 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=41 | not reported in cached trials |
| Oesophageal spasm | 93 | 68.0 55.2–83.7ROR 68.3 · χ² 5,758 / p <1e-300 | 63.7 EB05 53.6 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=93 | not reported in cached trials |
| Cystitis bacterial | 16 | 63.1 38.2–104.2ROR 63.1 · χ² 872 / p 5e-192 | 56.3 EB05 36.7 · IC025 +3.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=16 | not reported in cached trials |
| Hypopnoea | 129 | 49.5 41.6–59.0ROR 49.9 · χ² 5,854 / p <1e-300 | 47.4 EB05 40.9 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious n=128 · ♀ 22% (drug 84%) | not reported in cached trials |
| Autoimmune myositis | 16 | 46.3 28.1–76.2ROR 46.3 · χ² 641 / p 1e-141 | 42.6 EB05 27.8 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Rectal polyp | 33 | 43.7 30.9–61.8ROR 43.8 · χ² 1,289 / p 1e-282 | 41.3 EB05 30.8 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=33 | not reported in cached trials |
| Alcohol poisoning | 86 | 42.8 34.6–53.1ROR 43.0 · χ² 3,357 / p <1e-300 | 41.1 EB05 34.3 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=85 · ♀ 0% (drug 84%) · 95% clinician | not reported in cached trials |
| Chronic kidney disease-mineral and bone disorder | 27 | 32.9 22.5–48.2ROR 33.0 · χ² 783 / p 1e-172 | 31.5 EB05 22.7 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=27 | not reported in cached trials |
| Pigmentary maculopathy | 12 | 32.2 18.2–57.1ROR 32.2 · χ² 324 / p 1e-72 | 30.1 EB05 18.3 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=12 | not reported in cached trials |
| Coating in mouth | 13 | 32.0 18.4–55.4ROR 32.0 · χ² 351 / p 2e-78 | 30.0 EB05 18.6 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Oesophageal pain | 95 | 31.5 25.7–38.6ROR 31.7 · χ² 2,711 / p <1e-300 | 30.6 EB05 25.8 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=95 | not reported in cached trials |
| Nephrogenic anaemia | 109 | 30.5 25.2–36.9ROR 30.7 · χ² 3,010 / p <1e-300 | 29.7 EB05 25.3 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=109 | not reported in cached trials |
| Bronchiectasis | 150 | 29.4 25.1–34.6ROR 29.7 · χ² 4,002 / p <1e-300 | 28.7 EB05 25.1 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=150 · ♀ 31% (drug 84%) | not reported in cached trials |
| Obstructive sleep apnoea syndrome | 31 | 29.0 20.3–41.4ROR 29.1 · χ² 793 / p 1e-174 | 28.0 EB05 20.6 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=31 | not reported in cached trials |
| Change of bowel habit | 43 | 27.4 20.3–37.1ROR 27.5 · χ² 1,045 / p 1e-229 | 26.6 EB05 20.5 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=43 | not reported in cached trials |
| Hyperparathyroidism secondary | 53 | 27.3 20.8–35.9ROR 27.4 · χ² 1,290 / p 8e-283 | 26.5 EB05 21.1 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=53 | not reported in cached trials |
| Autoimmune hepatitis | 141 | 26.6 22.5–31.4ROR 26.8 · χ² 3,376 / p <1e-300 | 26.0 EB05 22.6 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious PRR 17.9 · 94% clinician | not reported in cached trials |
| Cardiac murmur | 177 | 26.5 22.9–30.8ROR 26.8 · χ² 4,238 / p <1e-300 | 26.0 EB05 22.9 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious PRR 20.2 · ♀ 43% (drug 84%) | not reported in cached trials |
| Dry age-related macular degeneration | 21 | 24.7 16.0–38.0ROR 24.7 · χ² 446 / p 3e-99 | 23.8 EB05 16.4 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=21 | not reported in cached trials |
| Rebound acid hypersecretion | 54 | 22.9 17.5–30.0ROR 23.0 · χ² 1,090 / p 3e-239 | 22.4 EB05 17.8 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=54 | not reported in cached trials |
| Alveolitis allergic | 18 | 22.4 14.0–35.6ROR 22.4 · χ² 340 / p 3e-76 | 21.5 EB05 14.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=18 | not reported in cached trials |
| Cleft palate | 33 | 22.2 15.7–31.3ROR 22.2 · χ² 635 / p 2e-140 | 21.6 EB05 16.0 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=33 | not reported in cached trials |
| Depressive symptom | 59 | 21.8 16.9–28.2ROR 21.9 · χ² 1,132 / p 2e-248 | 21.3 EB05 17.1 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=59 | not reported in cached trials |
| Rhinitis | 135 | 21.8 18.4–25.8ROR 21.9 · χ² 2,610 / p <1e-300 | 21.4 EB05 18.5 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=133 · ♀ 25% (drug 84%) | not reported in cached trials |
| Parosmia | 126 | 21.7 18.2–25.9ROR 21.9 · χ² 2,431 / p <1e-300 | 21.3 EB05 18.4 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=124 · ♀ 19% (drug 84%) · 90% clinician | not reported in cached trials |
| Gingival pain | 132 | 21.5 18.1–25.6ROR 21.7 · χ² 2,523 / p <1e-300 | 21.1 EB05 18.3 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=128 · ♀ 24% (drug 84%) · 91% clinician | not reported in cached trials |
| Lymphoedema | 110 | 20.7 17.2–25.0ROR 20.8 · χ² 2,010 / p <1e-300 | 20.3 EB05 17.3 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=108 | not reported in cached trials |
| Pulmonary toxicity | 106 | 19.6 16.2–23.7ROR 19.7 · χ² 1,824 / p <1e-300 | 19.3 EB05 16.4 · IC025 +3.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 13.8 · 100% clinician | not reported in cached trials |
| Opisthotonus | 12 | 19.4 11.0–34.3ROR 19.4 · χ² 189 / p 3e-43 | 18.2 EB05 10.5 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=12 | not reported in cached trials |
| Culture urine positive | 21 | 19.3 12.5–29.7ROR 19.3 · χ² 341 / p 2e-76 | 18.6 EB05 12.7 · IC025 +3.0 3/3 methods agree | Lab value / disease marker | serious n=21 | not reported in cached trials |
| Extensor plantar response | 13 | 18.2 10.5–31.4ROR 18.2 · χ² 191 / p 9e-44 | 17.1 EB05 9.9 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Systemic inflammatory response syndrome | 53 | 18.1 13.8–23.7ROR 18.1 · χ² 826 / p 7e-182 | 17.7 EB05 14.0 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=53 · 100% clinician | not reported in cached trials |
| Rales | 80 | 17.9 14.3–22.2ROR 17.9 · χ² 1,239 / p 1e-271 | 17.5 EB05 14.5 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=80 | not reported in cached trials |
| Nail infection | 19 | 17.2 10.9–27.0ROR 17.2 · χ² 270 / p 6e-61 | 16.5 EB05 10.8 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=19 | 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 Nitrofurantoin 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).
- NCT04187144 — Comparative Study to Evaluate Efficacy and Safety of Gepotidacin to Nitrofurantoin in Treatment of Uncomplicat (N=1606, PHASE3; 21 AE terms posted; arms: Gepotidacin; Nitrofurantoin)
- NCT04020341 — A Study to Evaluate Efficacy and Safety of Gepotidacin in the Treatment of Uncomplicated Urinary Tract Infecti (N=1531, PHASE3; 17 AE terms posted; arms: Gepotidacin; Nitrofurantoin)
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 |
|---|---|---|---|---|---|---|
| Urinary tract infection (bladder infection) | 1,365 | 10.3 9.8–10.9ROR 11.2 · χ² 11,508 / p <1e-300 | 10.3 EB05 9.8 · IC025 +3.3 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 7.9 | NCT04187144: 15/798 (1.9%) on Nitrofurantoin |
| Fatigue (tiredness) | 1,267 | 2.1 2.0–2.2ROR 2.2 · χ² 743 / p 5e-164 | 2.1 EB05 2.0 · IC025 +1.0 | Labeled (related wording) related wording | serious PRR 2.3 | NCT04187144: 8/798 (1.0%) on Nitrofurantoin |
| Nausea | 1,219 | 2.0 1.9–2.1ROR 2.1 · χ² 610 / p 5e-135 | 2.0 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.2 | NCT04187144: 35/798 (4.4%) on Nitrofurantoin |
| Headache | 1,136 | 2.3 2.2–2.5ROR 2.4 · χ² 879 / p 2e-193 | 2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.9 | NCT04187144: 22/798 (2.8%) on Nitrofurantoin |
| Pain | 988 | 2.1 1.9–2.2ROR 2.1 · χ² 550 / p 7e-122 | 2.1 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.1 | NCT04187144: 1/804 (0.1%) on Nitrofurantoin (serious AE) |
| Dyspnoea (shortness of breath) | 987 | 2.2 2.1–2.4ROR 2.3 · χ² 689 / p 4e-152 | 2.2 EB05 2.1 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.0 | not reported in cached trials |
| Diarrhoea (diarrhea) | 900 | 1.8 1.7–1.9ROR 1.8 · χ² 323 / p 2e-72 | 1.8 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 1.8 | NCT04187144: 24/798 (3.0%) on Nitrofurantoin |
| Rash | 875 | 2.6 2.4–2.8ROR 2.7 · χ² 864 / p 3e-190 | 2.6 EB05 2.4 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.3 | not reported in cached trials |
| Malaise (feeling unwell) | 860 | 2.5 2.3–2.7ROR 2.6 · χ² 791 / p 2e-174 | 2.5 EB05 2.4 · IC025 +1.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.7 | not reported in cached trials |
| Vomiting | 840 | 2.3 2.1–2.5ROR 2.4 · χ² 625 / p 4e-138 | 2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 | NCT04187144: 7/798 (0.9%) on Nitrofurantoin |
| Pyrexia (fever) | 819 | 3.0 2.8–3.2ROR 3.1 · χ² 1,128 / p 1e-247 | 3.0 EB05 2.9 · IC025 +1.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.5 | not reported in cached trials |
| Dizziness | 805 | 2.1 1.9–2.2ROR 2.1 · χ² 454 / p 5e-101 | 2.1 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.2 | NCT04187144: 11/798 (1.4%) on Nitrofurantoin |
| Drug ineffective (drug did not work) | 781 | 0.8 0.7–0.8ROR 0.7 · χ² 64 / p 7e-16 | 0.8 EB05 0.7 · IC025 -0.5 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.2 | not reported in cached trials |
| Off label use (used outside approved label) | 730 | 1.1 1.0–1.2ROR 1.1 · χ² 4 / p 0.023 | 1.1 EB05 1.0 · IC025 -0.0 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.2 | not reported in cached trials |
| Fall | 599 | 2.3 2.1–2.5ROR 2.4 · χ² 448 / p 8e-100 | 2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | 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.
- Heart sounds — n=57, PRR 1,843.2
- Prolonged expiration — n=57, PRR 352.4
- Steroid dependence — n=121, PRR 212.5
- Catarrh — n=124, PRR 207.4
- Burns second degree — n=126, PRR 99.3
- Sensitisation — n=41, PRR 72.3
- Oesophageal spasm — n=93, PRR 68.0
- Hypopnoea — n=129, PRR 49.5
- Rectal polyp — n=33, PRR 43.7
- Alcohol poisoning — n=86, PRR 42.8
✓ A hand-written Bradford Hill causality assessment exists for this drug: Nitrofurantoin ↔ Pulmonary fibrosis / interstitial lung disease.
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 Nitrofurantoin?
In FDA FAERS, the most frequently co-reported reaction terms for Nitrofurantoin are urinary tract infection, fatigue, nausea, headache, pain, dyspnoea. 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 Nitrofurantoin have an FDA boxed warning?
No. The FDA label retrieved for Nitrofurantoin has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Nitrofurantoin 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 11e700aa-66f9-4939-8a6b-a23240ae1a0b, effective 20240516; matched on
openfda.generic_name.exact:"NITROFURANTOIN") - 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, 1,181 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
NITROFURANTOIN, 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.