Iron side effects: what 66,429 FDA adverse event reports show

Iron · Real Summer · 1,179 reaction terms · 305,436 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Brand names

Real Summer

openFDA label

Who reports

66,429 reports · 65% serious · 4,707 with death outcome · 70% female

openFDA FAERS counts, all years, deduplication not applied

Used for

(s) ■ For temporary relief of pain and itching associated with insect bites.

FDA label, Indications and Usage

Boxed warning

None in the current label

How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation. Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)? That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.

Causality screen of the 40 strongest signals

Reporting / coding artifact 2Lab value / disease marker 10No label text to screen 28

What the badges mean

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.
No label text to screen No validated FDA label was retrievable for this product, so the screen could not run. Disproportionality only.

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, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,139 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Granuloma skin	97	41.8 33.8–51.6ROR 41.8 · calibrated p 5e-5 ✓	36.7 EB05 30.9 · IC025 +4.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=97 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Blood parathyroid hormone decreased	104	23.6 19.3–28.8ROR 23.6 · calibrated p 1e-3 ✓	21.9 EB05 18.6 · IC025 +4.0 3/3 methods agree	Lab value / disease marker	serious n=103 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Blood iron decreased	765	21.8 20.3–23.5ROR 22.1 · calibrated p 0.001 ✓	20.5 EB05 19.3 · IC025 +4.2 3/3 methods agree	Lab value / disease marker	serious PRR 19.6	NCT03037931: 2/1,533 (0.1%) control (serious AE)
Iron deficiency	204	15.1 13.1–17.4ROR 15.2 · calibrated p 0.007 ✓	14.4 EB05 12.8 · IC025 +3.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=180	NCT03037931: 2/1,533 (0.1%) control (serious AE)
Blood pressure diastolic abnormal	116	14.9 12.3–17.9ROR 14.9 · calibrated p 0.008 ✓	14.2 EB05 12.1 · IC025 +3.4 3/3 methods agree	Lab value / disease marker	serious n=111 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Serum ferritin decreased	75	14.4 11.4–18.1ROR 14.4 · calibrated p 0.009 ✓	13.7 EB05 11.2 · IC025 +3.3 3/3 methods agree	Lab value / disease marker	serious n=68	not reported in cached trials
Therapeutic reaction time decreased	119	13.3 11.0–15.9ROR 13.3 · calibrated p 0.012 ✓	12.7 EB05 10.8 · IC025 +3.3 3/3 methods agree	Lab value / disease marker	serious n=117	not reported in cached trials
Panniculitis	97	13.2 10.8–16.2ROR 13.2 · calibrated p 0.012 ✓	12.6 EB05 10.6 · IC025 +3.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=97 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Blood pressure systolic abnormal	96	12.6 10.3–15.5ROR 12.6 · calibrated p 0.015 ✓	12.0 EB05 10.1 · IC025 +3.2 3/3 methods agree	Lab value / disease marker	serious n=87 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Rheumatoid nodule	102	12.0 9.8–14.6ROR 12.0 · calibrated p 0.018 ✓	11.4 EB05 9.6 · IC025 +3.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=101 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Hyperparathyroidism secondary	91	11.7 9.5–14.5ROR 11.7 · calibrated p 0.019 ✓	11.2 EB05 9.3 · IC025 +3.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=91	not reported in cached trials
Iron deficiency anaemia	290	10.3 9.1–11.5ROR 10.3 · calibrated p 0.030 ✓	9.9 EB05 9.0 · IC025 +3.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 9.0	NCT03037931: 2/1,533 (0.1%) control (serious AE)
Drug tolerance decreased	88	10.2 8.3–12.6ROR 10.2 · calibrated p 0.032 ✓	9.7 EB05 8.1 · IC025 +2.9 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=81 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Faecal calprotectin increased	93	9.7 7.9–11.9ROR 9.7 · calibrated p 0.038 ✓	9.2 EB05 7.7 · IC025 +2.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=88	not reported in cached trials
Sinus pain	66	9.3 7.3–11.8ROR 9.3 · calibrated p 0.045 ✓	8.7 EB05 7.0 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=63 · ♀ 100% (drug 70%)	not reported in cached trials
Nephrogenic anaemia	130	9.0 7.6–10.7ROR 9.0 · calibrated p 0.047 ✓	8.6 EB05 7.4 · IC025 +2.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=130	not reported in cached trials
Blood iron increased	52	8.9 6.8–11.8ROR 8.9 · calibrated p 0.051	8.3 EB05 6.5 · IC025 +2.6 3/3 methods agree	Lab value / disease marker	serious n=40 · 100% consumer	NCT03037931: 2/1,533 (0.1%) control (serious AE)
Breath sounds abnormal	133	8.7 7.3–10.4ROR 8.7 · calibrated p 0.052	8.3 EB05 7.2 · IC025 +2.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=130	not reported in cached trials
Mucous stools	131	8.6 7.2–10.2ROR 8.6 · calibrated p 0.055	8.2 EB05 7.1 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=123	not reported in cached trials
Vascular device infection	119	8.5 7.1–10.2ROR 8.5 · calibrated p 0.056	8.1 EB05 7.0 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=118	not reported in cached trials
Infusion site bruising	56	8.5 6.5–11.1ROR 8.5 · calibrated p 0.059	7.9 EB05 6.3 · IC025 +2.5 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=44 · ♀ 100% (drug 70%) · 100% consumer	not reported in cached trials
Nephrogenic systemic fibrosis	80	8.4 6.8–10.5ROR 8.5 · calibrated p 0.059	8.0 EB05 6.6 · IC025 +2.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=80 · ♀ 46% (drug 70%) · 100% clinician	not reported in cached trials
Anal fissure	135	8.2 6.9–9.7ROR 8.2 · calibrated p 0.064	7.8 EB05 6.8 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=134	not reported in cached trials
Premature labour	143	8.1 6.9–9.5ROR 8.1 · calibrated p 0.066	7.8 EB05 6.7 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=140 · ♀ 100% (drug 70%)	not reported in cached trials
Defaecation urgency	173	8.0 6.9–9.3ROR 8.0 · calibrated p 0.067	7.7 EB05 6.8 · IC025 +2.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=154	not reported in cached trials
Infusion site haemorrhage	80	8.0 6.4–9.9ROR 8.0 · calibrated p 0.071	7.5 EB05 6.2 · IC025 +2.5 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=52	NCT03037931: 1/1,533 (0.1%) control (serious AE)
Rheumatoid factor positive	133	7.4 6.2–8.8ROR 7.4 · calibrated p 0.085	7.1 EB05 6.2 · IC025 +2.5 3/3 methods agree	Lab value / disease marker	serious n=133 · ♀ 100% (drug 70%) · 100% clinician	not reported in cached trials
Drug level below therapeutic	126	7.4 6.2–8.8ROR 7.4 · calibrated p 0.087	7.1 EB05 6.1 · IC025 +2.5 3/3 methods agree	Reporting / coding artifact	serious n=124 · 100% clinician	NCT03037931: 1/1,532 (0.1%) on Iron (serious AE)
Polyp	150	7.4 6.3–8.7ROR 7.4 · calibrated p 0.086	7.1 EB05 6.2 · IC025 +2.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=143	NCT03037931: 1/1,532 (0.1%) on Iron (serious AE)
Poor venous access	235	7.3 6.4–8.3ROR 7.4 · calibrated p 0.087	7.1 EB05 6.4 · IC025 +2.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=226	not reported in cached trials
Blood pressure diastolic decreased	166	7.2 6.2–8.4ROR 7.2 · calibrated p 0.092	6.9 EB05 6.1 · IC025 +2.5 3/3 methods agree	Lab value / disease marker	serious PRR 6.4	not reported in cached trials
Intestinal stenosis	94	7.2 5.9–8.8ROR 7.2 · calibrated p 0.094	6.8 EB05 5.7 · IC025 +2.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=93	not reported in cached trials
Drug level decreased	215	6.8 5.9–7.7ROR 6.8 · calibrated p 0.110	6.5 EB05 5.8 · IC025 +2.5 3/3 methods agree	Reporting / coding artifact	serious PRR 6.7	NCT03037931: 3/1,532 (0.2%) on Iron; 4/1,533 (0.3%) control (serious AE)
Frequent bowel movements	559	6.7 6.1–7.3ROR 6.7 · calibrated p 0.111	6.5 EB05 6.1 · IC025 +2.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 6.9 · serious PRR 7.7	not reported in cached trials
Colitis ulcerative	923	6.6 6.2–7.1ROR 6.7 · calibrated p 0.111	6.5 EB05 6.2 · IC025 +2.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 7.5 · serious PRR 5.9	not reported in cached trials
Uterine leiomyoma	149	6.5 5.5–7.7ROR 6.5 · calibrated p 0.122	6.3 EB05 5.5 · IC025 +2.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=127 · ♀ 100% (drug 70%)	not reported in cached trials
Blood phosphorus increased	54	6.4 4.9–8.3ROR 6.4 · calibrated p 0.135	6.0 EB05 4.7 · IC025 +2.1 3/3 methods agree	Lab value / disease marker	serious n=51 · ♀ 0% (drug 70%) · 100% clinician	not reported in cached trials
Gastrointestinal inflammation	154	6.4 5.4–7.4ROR 6.4 · calibrated p 0.131	6.1 EB05 5.4 · IC025 +2.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 5.5	not reported in cached trials
Faeces soft	143	6.3 5.4–7.5ROR 6.4 · calibrated p 0.131	6.1 EB05 5.3 · IC025 +2.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=119	not reported in cached trials
Skin necrosis	102	6.3 5.2–7.6ROR 6.3 · calibrated p 0.136	6.0 EB05 5.1 · IC025 +2.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=102 · ♀ 100% (drug 70%) · 100% clinician	NCT03037931: 1/1,533 (0.1%) control (serious AE)

Clinical concept groups

MedDRA splits one clinical problem across several terms (e.g. "neutropenia", "neutrophil count decreased", "agranulocytosis"), which dilutes term-level signals. These rows count reports with any term in a concept group (an exact union, not a sum), compared with all other drugs. Groups are hand-built and listed in the methods.

Concept	Reports	PRR 95% CI	Reading
Anaemia	4,213	4.54.4–4.6	signal
Gi bleeding	1,660	2.92.7–3.0	signal
Fall / fracture	2,708	2.32.2–2.3	signal
Serious infection	5,225	2.12.1–2.2	signal
Venous thromboembolism	1,279	1.91.8–2.0	raised
Heart failure	960	1.71.6–1.8	raised
Depression	1,499	1.71.6–1.8	raised
Opportunistic infection	700	1.61.5–1.7	raised
Arrhythmia / qt	977	1.61.5–1.7	raised
Kidney injury	2,272	1.61.5–1.6	raised
Thrombocytopenia	1,053	1.51.4–1.6	raised
Hyponatraemia	370	1.51.3–1.6	raised
Tendon disorder	168	1.41.2–1.6	raised
Interstitial lung disease	393	1.31.2–1.4	raised
Hypoglycaemia	375	1.21.1–1.4	raised
Hyperglycaemia / diabetes	1,239	1.11.1–1.2	raised

Trial evidence (ClinicalTrials.gov)

✓ Trial adverse-event data found on ClinicalTrials.gov

Largest completed trials with posted results that list Iron 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 (9 of 40 signal terms matched).

NCT03037931 — Randomized Placebo-controlled Trial of FCM as Treatment for Heart Failure With Iron Deficiency / and Sub-Study (N=3065, PHASE3; 533 AE terms posted; arms: Ferric Carboxymaltose; Placebo)

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
Fatigue (tiredness)	6,078	2.5 2.4–2.5ROR 2.6 · calibrated p 0.760	2.5 EB05 2.4 · IC025 +1.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.3 · serious PRR 2.8	not reported in cached trials
Off label use (used outside approved label)	5,297	1.9 1.9–2.0ROR 2.0 · calibrated p 0.951	1.9 EB05 1.9 · IC025 +0.9	Reporting / coding artifact	age-adj. PRR 1.9 · serious PRR 2.6	not reported in cached trials
Diarrhoea (diarrhea)	4,938	2.4 2.4–2.5ROR 2.5 · calibrated p 0.793	2.4 EB05 2.4 · IC025 +1.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.2 · serious PRR 2.6	NCT03037931: 1/1,532 (0.1%) on Iron (serious AE)
Nausea	4,734	1.9 1.8–2.0ROR 2.0 · calibrated p 0.926	1.9 EB05 1.8 · IC025 +0.9	No label text to screen label has no adverse-reaction text	age-adj. PRR 1.8 · serious PRR 2.2	NCT03037931: 1/1,532 (0.1%) on Iron; 5/1,533 (0.3%) control (serious AE)
Drug ineffective (drug did not work)	4,321	1.0 1.0–1.1ROR 1.0 · calibrated p 0.331	1.0 EB05 1.0 · IC025 +0.0	Reporting / coding artifact	age-adj. PRR 1.3 · serious PRR 1.7	not reported in cached trials
Headache	3,928	2.0 1.9–2.0ROR 2.0 · calibrated p 0.970	2.0 EB05 1.9 · IC025 +0.9	No label text to screen label has no adverse-reaction text	age-adj. PRR 1.9 · serious PRR 2.3	not reported in cached trials
Pain	3,635	1.9 1.8–1.9ROR 1.9 · calibrated p 0.899	1.9 EB05 1.8 · IC025 +0.8	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.1 · serious PRR 1.9	NCT03037931: 1/1,532 (0.1%) on Iron; 1/1,533 (0.1%) control (serious AE)
Dyspnoea (shortness of breath)	3,586	2.0 1.9–2.1ROR 2.1 · calibrated p 0.979	2.0 EB05 1.9 · IC025 +0.9	No label text to screen label has no adverse-reaction text	age-adj. PRR 1.8 · serious PRR 2.0	NCT03037931: 1/1,533 (0.1%) control (serious AE)
Dizziness	3,188	2.0 2.0–2.1ROR 2.1 · calibrated p 0.986	2.0 EB05 2.0 · IC025 +1.0	No label text to screen label has no adverse-reaction text	age-adj. PRR 1.9 · serious PRR 2.2	NCT03037931: 4/1,532 (0.3%) on Iron; 3/1,533 (0.2%) control (serious AE)
Arthralgia (joint pain)	3,149	2.4 2.3–2.5ROR 2.5 · calibrated p 0.822	2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.2 · serious PRR 2.9	NCT03037931: 5/1,532 (0.3%) on Iron (serious AE)
Asthenia (weakness)	2,929	2.5 2.4–2.6ROR 2.5 · calibrated p 0.798	2.5 EB05 2.4 · IC025 +1.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.1 · serious PRR 2.5	NCT03037931: 4/1,532 (0.3%) on Iron; 4/1,533 (0.3%) control (serious AE)
Vomiting	2,792	1.9 1.8–2.0ROR 1.9 · calibrated p 0.901	1.9 EB05 1.8 · IC025 +0.8	No label text to screen label has no adverse-reaction text	age-adj. PRR 1.8 · serious PRR 1.9	NCT03037931: 4/1,533 (0.3%) control (serious AE)
Anaemia (low red blood cells)	2,660	4.4 4.3–4.6ROR 4.6 · calibrated p 0.284	4.4 EB05 4.3 · IC025 +2.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 3.7 · serious PRR 3.7	NCT03037931: 7/1,532 (0.5%) on Iron; 15/1,533 (1.0%) control (serious AE)
Weight decreased (weight loss)	2,536	2.9 2.8–3.0ROR 3.0 · calibrated p 0.640	2.9 EB05 2.8 · IC025 +1.5 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.6 · serious PRR 3.2	not reported in cached trials
Fall	2,514	2.4 2.3–2.5ROR 2.5 · calibrated p 0.834	2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	age-adj. PRR 2.1 · serious PRR 2.2	NCT03037931: 5/1,532 (0.3%) on Iron; 4/1,533 (0.3%) control (serious AE)

Unlabeled candidate signals

Every screened signal with n ≥ 20 was either labeled, an indication term, or an artifact pattern — no unlabeled candidate stood out in the top signals.

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 Iron?

In FDA FAERS, the most frequently co-reported reaction terms for Iron are fatigue, diarrhoea, 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 Iron have an FDA boxed warning?

No. The FDA label retrieved for Iron has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Iron 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 63021d49-8720-4e4e-a08f-a5d2f6acfaa5, effective 20241209; matched on openfda.generic_name.exact:"IRON")
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, field patient.drug.openfda.generic_name.exact, 1,179 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 IRON, results-bearing studies sorted by enrollment)

Page generated 2026-10-14. 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.