Drug · FAERS side-effect profile with label screen
Vitamin C side effects: what 91,280 FDA adverse event reports show
Brand names
Vitamin C Serum
openFDA label
Who reports
91,280 reports · 59% serious · 7,889 with death outcome · 69% female
openFDA FAERS counts, all years, deduplication not applied
Used for
SECTION INDICATIONS & USAGE SECTION INDICATIONS & USAGE SECTION
FDA label, Indications and Usage
What it is
L-ascorbic acid is the L-enantiomer of ascorbic acid and conjugate acid of L-ascorbate. It has a role as a geroprotector, a coenzyme, a cofactor, a flour treatment agent, a plant metabolite, a food antioxidant, a food colour retention agent and a skin lightening agent.
PubChem CID 54670067 (ChEBI)
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 3Lab value / disease marker 7No label text to screen 30
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). 1,160 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Sleep disorder therapy | 92 | 225.5 168.9–301.1ROR 225.7 · calibrated p 3e-10 ✓ | 110.7 EB05 93.0 · IC025 +5.8 3/3 methods agree vs other Vitamin Cs: PRR 4.7 (3.5–6.2) | Reporting / coding artifact | serious n=92 · ♀ 0% (drug 69%) · 100% clinician | not reported in cached trials |
| C-reactive protein | 390 | 173.8 152.3–198.3ROR 174.6 · calibrated p 1e-9 ✓ | 98.1 EB05 90.2 · IC025 +6.3 3/3 methods agree vs other Vitamin Cs: PRR 19.7 (15.7–24.8) | Lab value / disease marker | serious n=390 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Deep vein thrombosis postoperative | 807 | 161.2 147.3–176.4ROR 162.6 · calibrated p 2e-9 ✓ | 94.2 EB05 88.9 · IC025 +6.4 3/3 methods agree vs other Vitamin Cs: PRR 15.0 (13.0–17.3) | No label text to screen label has no adverse-reaction text | serious n=807 · ♀ 100% (drug 69%) · 92% clinician | not reported in cached trials |
| Lupus vulgaris | 482 | 156.9 139.7–176.2ROR 157.7 · calibrated p 3e-9 ✓ | 92.6 EB05 85.9 · IC025 +6.3 3/3 methods agree vs other Vitamin Cs: PRR 16.5 (13.6–20.0) | No label text to screen label has no adverse-reaction text | serious n=482 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Anti-cyclic citrullinated peptide antibody | 263 | 149.8 128.2–175.0ROR 150.2 · calibrated p 5e-9 ✓ | 89.8 EB05 81.1 · IC025 +6.1 3/3 methods agree vs other Vitamin Cs: PRR 22.2 (16.6–29.7) | Lab value / disease marker | serious n=263 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Appendicolith | 146 | 143.8 116.8–176.9ROR 144.0 · calibrated p 9e-9 ✓ | 87.2 EB05 76.0 · IC025 +5.8 3/3 methods agree vs other Vitamin Cs: PRR 3.3 (2.6–4.0) | No label text to screen label has no adverse-reaction text | serious n=146 · ♀ 0% (drug 69%) · 100% clinician | not reported in cached trials |
| Rheumatic fever | 1,519 | 122.7 115.3–130.5ROR 124.7 · calibrated p 2e-8 ✓ | 79.7 EB05 76.4 · IC025 +6.2 3/3 methods agree vs other Vitamin Cs: PRR 20.9 (18.6–23.5) | No label text to screen label has no adverse-reaction text | serious n=1,519 · ♀ 100% (drug 69%) · 95% clinician | not reported in cached trials |
| Swollen joint count increased | 1,073 | 120.6 112.0–129.9ROR 122.1 · calibrated p 2e-8 ✓ | 78.8 EB05 75.0 · IC025 +6.2 3/3 methods agree vs other Vitamin Cs: PRR 19.4 (16.9–22.2) | Lab value / disease marker | serious n=1,073 · ♀ 100% (drug 69%) · 96% clinician | not reported in cached trials |
| Swollen joint count | 83 | 117.0 89.8–152.5ROR 117.1 · calibrated p 6e-8 ✓ | 76.1 EB05 63.3 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 12.6 (8.3–19.1) | No label text to screen label has no adverse-reaction text | serious n=83 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Facet joint syndrome | 1,046 | 114.2 106.0–123.0ROR 115.5 · calibrated p 4e-8 ✓ | 76.0 EB05 72.2 · IC025 +6.1 3/3 methods agree vs other Vitamin Cs: PRR 17.1 (15.0–19.5) | No label text to screen label has no adverse-reaction text | serious n=1,045 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Grip strength | 70 | 99.3 75.0–131.5ROR 99.4 · calibrated p 2e-7 ✓ | 68.0 EB05 55.7 · IC025 +5.1 3/3 methods agree vs other Vitamin Cs: PRR 6.3 (4.4–9.0) | No label text to screen label has no adverse-reaction text | serious n=70 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Hypocholesterolaemia | 92 | 97.9 76.6–125.0ROR 98.0 · calibrated p 2e-7 ✓ | 67.6 EB05 56.8 · IC025 +5.3 3/3 methods agree vs other Vitamin Cs: only this drug | No label text to screen label has no adverse-reaction text | serious n=92 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Analgesic therapy | 88 | 92.3 72.0–118.3ROR 92.4 · calibrated p 3e-7 ✓ | 64.9 EB05 54.3 · IC025 +5.2 3/3 methods agree vs other Vitamin Cs: PRR 4.3 (3.2–5.7) | Reporting / coding artifact | serious n=88 · ♀ 0% (drug 69%) · 100% clinician | not reported in cached trials |
| Ejection fraction | 166 | 91.1 76.1–109.1ROR 91.3 · calibrated p 3e-7 ✓ | 64.7 EB05 56.9 · IC025 +5.5 3/3 methods agree vs other Vitamin Cs: PRR 23.6 (16.2–34.5) | No label text to screen label has no adverse-reaction text | serious n=166 · ♀ 100% (drug 69%) | not reported in cached trials |
| X-ray abnormal | 487 | 86.1 77.6–95.6ROR 86.6 · calibrated p 3e-7 ✓ | 62.5 EB05 57.9 · IC025 +5.7 3/3 methods agree vs other Vitamin Cs: PRR 14.7 (12.2–17.6) | Lab value / disease marker | serious n=486 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Sensitisation | 207 | 85.0 72.5–99.8ROR 85.2 · calibrated p 4e-7 ✓ | 61.7 EB05 55.0 · IC025 +5.5 3/3 methods agree vs other Vitamin Cs: PRR 21.4 (15.5–29.7) | No label text to screen label has no adverse-reaction text | serious n=207 · ♀ 100% (drug 69%) | not reported in cached trials |
| Subcutaneous drug absorption impaired | 147 | 84.8 70.1–102.5ROR 84.9 · calibrated p 5e-7 ✓ | 61.4 EB05 53.5 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 15.9 (11.3–22.5) | No label text to screen label has no adverse-reaction text | serious n=147 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Drug therapy | 77 | 72.7 56.2–93.9ROR 72.7 · calibrated p 2e-6 ✓ | 54.5 EB05 45.0 · IC025 +5.0 3/3 methods agree vs other Vitamin Cs: PRR 3.9 (2.9–5.3) | Reporting / coding artifact | serious n=77 · ♀ 0% (drug 69%) · 100% clinician | not reported in cached trials |
| Peripheral venous disease | 955 | 72.1 67.1–77.5ROR 72.9 · calibrated p 1e-6 ✓ | 54.8 EB05 52.0 · IC025 +5.6 3/3 methods agree vs other Vitamin Cs: PRR 20.6 (17.8–23.9) | No label text to screen label has no adverse-reaction text | serious n=953 · ♀ 100% (drug 69%) · 92% clinician | not reported in cached trials |
| Adjustment disorder with depressed mood | 475 | 70.7 63.8–78.4ROR 71.1 · calibrated p 1e-6 ✓ | 54.0 EB05 50.0 · IC025 +5.5 3/3 methods agree vs other Vitamin Cs: PRR 14.0 (11.6–16.7) | No label text to screen label has no adverse-reaction text | serious n=473 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Duodenal ulcer perforation | 1,697 | 69.0 65.3–72.8ROR 70.3 · calibrated p 1e-6 ✓ | 53.0 EB05 50.9 · IC025 +5.6 3/3 methods agree vs other Vitamin Cs: PRR 17.3 (15.6–19.2) | No label text to screen label has no adverse-reaction text | serious PRR 52.0 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Retinitis | 359 | 62.8 55.9–70.6ROR 63.1 · calibrated p 3e-6 ✓ | 49.2 EB05 45.1 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 17.8 (14.1–22.3) | No label text to screen label has no adverse-reaction text | serious n=359 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Dislocation of vertebra | 474 | 62.1 56.1–68.7ROR 62.4 · calibrated p 3e-6 ✓ | 48.8 EB05 45.2 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 15.6 (12.9–18.9) | No label text to screen label has no adverse-reaction text | serious n=474 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Rheumatoid factor positive | 1,194 | 59.8 56.1–63.7ROR 60.6 · calibrated p 4e-6 ✓ | 47.5 EB05 45.2 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 18.8 (16.6–21.4) | Lab value / disease marker | serious n=1,193 · ♀ 100% (drug 69%) · 95% clinician | not reported in cached trials |
| Anti-cyclic citrullinated peptide antibody positive | 1,457 | 59.1 55.8–62.6ROR 60.1 · calibrated p 4e-6 ✓ | 47.0 EB05 45.0 · IC025 +5.4 3/3 methods agree vs other Vitamin Cs: PRR 19.7 (17.5–22.2) | Lab value / disease marker | serious PRR 46.3 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Temperature regulation disorder | 426 | 55.5 49.9–61.7ROR 55.8 · calibrated p 7e-6 ✓ | 44.7 EB05 41.2 · IC025 +5.3 3/3 methods agree vs other Vitamin Cs: PRR 18.1 (14.7–22.4) | No label text to screen label has no adverse-reaction text | serious n=423 · ♀ 100% (drug 69%) | not reported in cached trials |
| C-reactive protein abnormal | 1,160 | 50.7 47.5–54.0ROR 51.3 · calibrated p 1e-5 ✓ | 41.5 EB05 39.6 · IC025 +5.3 3/3 methods agree vs other Vitamin Cs: PRR 17.0 (15.0–19.2) | Lab value / disease marker | serious n=1,159 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Muscle injury | 1,455 | 49.4 46.7–52.2ROR 50.2 · calibrated p 1e-5 ✓ | 40.7 EB05 38.9 · IC025 +5.2 3/3 methods agree vs other Vitamin Cs: PRR 15.6 (14.0–17.4) | No label text to screen label has no adverse-reaction text | serious PRR 43.1 · ♀ 100% (drug 69%) · 92% clinician | not reported in cached trials |
| Sleep disorder due to general medical condition, insomnia type | 1,086 | 46.5 43.6–49.6ROR 47.0 · calibrated p 2e-5 ✓ | 38.7 EB05 36.8 · IC025 +5.1 3/3 methods agree vs other Vitamin Cs: PRR 17.3 (15.2–19.7) | No label text to screen label has no adverse-reaction text | serious n=1,079 · ♀ 100% (drug 69%) · 92% clinician | not reported in cached trials |
| Helicobacter infection | 1,717 | 46.4 44.1–48.9ROR 47.3 · calibrated p 2e-5 ✓ | 38.6 EB05 37.1 · IC025 +5.2 3/3 methods agree vs other Vitamin Cs: PRR 18.2 (16.4–20.2) | No label text to screen label has no adverse-reaction text | serious PRR 39.8 · ♀ 100% (drug 69%) · 92% clinician | not reported in cached trials |
| Coombs positive haemolytic anaemia | 74 | 43.5 33.9–55.7ROR 43.5 · calibrated p 4e-5 ✓ | 36.3 EB05 29.9 · IC025 +4.5 3/3 methods agree vs other Vitamin Cs: only this drug | No label text to screen label has no adverse-reaction text | serious n=74 · ♀ 0% (drug 69%) · 100% clinician | not reported in cached trials |
| Folliculitis | 1,625 | 42.8 40.6–45.1ROR 43.5 · calibrated p 3e-5 ✓ | 36.1 EB05 34.6 · IC025 +5.1 3/3 methods agree vs other Vitamin Cs: PRR 15.2 (13.7–16.8) | No label text to screen label has no adverse-reaction text | serious PRR 41.4 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Pemphigus | 1,934 | 42.2 40.2–44.3ROR 43.1 · calibrated p 3e-5 ✓ | 35.7 EB05 34.4 · IC025 +5.1 3/3 methods agree vs other Vitamin Cs: PRR 20.1 (18.1–22.3) | No label text to screen label has no adverse-reaction text | serious PRR 35.1 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Overlap syndrome | 96 | 37.0 29.8–45.9ROR 37.0 · calibrated p 1e-4 ✓ | 31.8 EB05 26.8 · IC025 +4.4 3/3 methods agree vs other Vitamin Cs: only this drug | No label text to screen label has no adverse-reaction text | serious n=96 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Hand deformity | 1,795 | 36.4 34.7–38.3ROR 37.1 · calibrated p 8e-5 ✓ | 31.5 EB05 30.3 · IC025 +4.9 3/3 methods agree vs other Vitamin Cs: PRR 19.1 (17.2–21.3) | No label text to screen label has no adverse-reaction text | serious PRR 33.5 · ♀ 100% (drug 69%) · 93% clinician | not reported in cached trials |
| Polycystic ovaries | 211 | 35.5 30.7–41.1ROR 35.6 · calibrated p 1e-4 ✓ | 30.7 EB05 27.4 · IC025 +4.6 3/3 methods agree vs other Vitamin Cs: PRR 20.9 (15.2–28.7) | No label text to screen label has no adverse-reaction text | serious n=208 · ♀ 100% (drug 69%) | not reported in cached trials |
| Lip dry | 1,182 | 34.8 32.7–37.0ROR 35.2 · calibrated p 1e-4 ✓ | 30.3 EB05 28.8 · IC025 +4.8 3/3 methods agree vs other Vitamin Cs: PRR 21.8 (19.0–25.0) | No label text to screen label has no adverse-reaction text | serious n=1,151 · ♀ 98% (drug 69%) · 90% clinician | not reported in cached trials |
| Porphyria acute | 166 | 31.3 26.6–36.8ROR 31.3 · calibrated p 2e-4 ✓ | 27.5 EB05 24.2 · IC025 +4.4 3/3 methods agree vs other Vitamin Cs: PRR 13.5 (10.0–18.3) | No label text to screen label has no adverse-reaction text | serious n=166 · ♀ 100% (drug 69%) · 100% clinician | not reported in cached trials |
| Bursitis | 1,446 | 31.2 29.5–32.9ROR 31.7 · calibrated p 2e-4 ✓ | 27.5 EB05 26.3 · IC025 +4.7 3/3 methods agree vs other Vitamin Cs: PRR 12.6 (11.4–13.9) | No label text to screen label has no adverse-reaction text | serious PRR 31.3 · ♀ 98% (drug 69%) | not reported in cached trials |
| Breast cancer stage iii | 728 | 29.2 27.0–31.5ROR 29.4 · calibrated p 3e-4 ✓ | 26.0 EB05 24.4 · IC025 +4.6 3/3 methods agree vs other Vitamin Cs: PRR 17.9 (15.3–21.0) | No label text to screen label has no adverse-reaction text | serious n=728 · ♀ 100% (drug 69%) · 94% clinician | not reported in cached trials |
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 |
|---|---|---|---|
| Liver injury | 4,055 | 3.13.0–3.2 | signal |
| Tendon disorder | 459 | 2.82.5–3.1 | signal |
| Serious infection | 8,518 | 2.52.5–2.6 | signal |
| Interstitial lung disease | 1,016 | 2.42.3–2.6 | signal |
| Fall / fracture | 4,027 | 2.42.4–2.5 | signal |
| Depression | 2,927 | 2.42.3–2.5 | signal |
| Hyperglycaemia / diabetes | 3,190 | 2.12.1–2.2 | signal |
| Anaemia | 2,592 | 2.01.9–2.1 | raised |
| Thrombocytopenia | 1,764 | 1.81.8–1.9 | raised |
| Opportunistic infection | 1,085 | 1.81.7–1.9 | raised |
| Hyponatraemia | 608 | 1.71.6–1.9 | raised |
| Gi bleeding | 1,263 | 1.61.5–1.7 | raised |
| Venous thromboembolism | 1,404 | 1.51.4–1.6 | raised |
| Arrhythmia / qt | 1,202 | 1.41.3–1.5 | raised |
| Pancreatitis | 438 | 1.21.1–1.4 | raised |
| Kidney injury | 2,181 | 1.11.1–1.1 | raised |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Vitamin C 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).
- NCT01351805 — Vitamin D and Fish Oil for Autoimmune Disease, Inflammation and Knee Pain (N=25871, NA; 24 AE terms posted; arms: Active Vitamin D/ Active Omega-3 Fatty A; Active Vitamin D/ Active Omega-3 Placebo; Active Omega-3 Fatty Acids, Placebo Vita; Omega-3 Fatty Acids Placebo/ Placebo Vit)
- NCT00135707 — Combined Antioxidant and Preeclampsia Prediction Studies (CAPPS) (N=10154, PHASE3; 20 AE terms posted; arms: Vitamins; 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) | 11,061 | 3.3 3.2–3.4ROR 3.6 · calibrated p 0.456 | 3.3 EB05 3.2 · IC025 +1.7 3/3 methods agree vs other Vitamin Cs: PRR 9.8 (9.5–10.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 3.0 · serious PRR 4.0 | not reported in cached trials |
| Headache | 7,939 | 2.9 2.9–3.0ROR 3.1 · calibrated p 0.589 | 2.9 EB05 2.9 · IC025 +1.5 3/3 methods agree vs other Vitamin Cs: PRR 9.3 (9.0–9.7) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.8 · serious PRR 4.0 | not reported in cached trials |
| Pain | 7,737 | 2.9 2.8–3.0ROR 3.1 · calibrated p 0.598 | 2.9 EB05 2.8 · IC025 +1.5 3/3 methods agree vs other Vitamin Cs: PRR 8.8 (8.5–9.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 3.2 · serious PRR 3.5 | NCT01351805: 2422/6,474 (37.4%) on Vitamin C; 2421/6,464 (37.5%) control |
| Nausea | 7,687 | 2.2 2.2–2.3ROR 2.4 · calibrated p 0.873 | 2.2 EB05 2.2 · IC025 +1.1 3/3 methods agree vs other Vitamin Cs: PRR 7.9 (7.6–8.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.1 · serious PRR 2.8 | NCT01351805: 1779/6,474 (27.5%) on Vitamin C; 1771/6,464 (27.4%) control |
| Diarrhoea (diarrhea) | 7,521 | 2.7 2.6–2.8ROR 2.9 · calibrated p 0.674 | 2.7 EB05 2.6 · IC025 +1.4 3/3 methods agree vs other Vitamin Cs: PRR 8.4 (8.1–8.7) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.4 · serious PRR 3.0 | NCT01351805: 2850/6,474 (44.0%) on Vitamin C; 2730/6,464 (42.2%) control |
| Off label use (used outside approved label) | 7,403 | 2.0 1.9–2.0ROR 2.1 · calibrated p 0.972 | 2.0 EB05 1.9 · IC025 +0.9 vs other Vitamin Cs: PRR 12.1 (11.6–12.6) | Reporting / coding artifact | age-adj. PRR 2.0 · serious PRR 2.7 | not reported in cached trials |
| Drug ineffective (drug did not work) | 7,341 | 1.3 1.3–1.3ROR 1.3 · calibrated p 0.512 | 1.3 EB05 1.3 · IC025 +0.3 vs other Vitamin Cs: PRR 8.6 (8.3–8.9) | Reporting / coding artifact | age-adj. PRR 1.6 · serious PRR 2.3 | not reported in cached trials |
| Dyspnoea (shortness of breath) | 5,956 | 2.4 2.4–2.5ROR 2.5 · calibrated p 0.799 | 2.4 EB05 2.4 · IC025 +1.2 3/3 methods agree vs other Vitamin Cs: PRR 7.8 (7.5–8.2) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.2 · serious PRR 2.6 | not reported in cached trials |
| Arthralgia (joint pain) | 5,674 | 3.2 3.1–3.3ROR 3.3 · calibrated p 0.532 | 3.1 EB05 3.1 · IC025 +1.6 3/3 methods agree vs other Vitamin Cs: PRR 8.7 (8.4–9.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 3.0 · serious PRR 4.2 | not reported in cached trials |
| Dizziness | 5,632 | 2.6 2.5–2.7ROR 2.7 · calibrated p 0.724 | 2.6 EB05 2.5 · IC025 +1.3 3/3 methods agree vs other Vitamin Cs: PRR 8.1 (7.8–8.5) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.4 · serious PRR 3.1 | not reported in cached trials |
| Rash | 5,340 | 2.9 2.8–2.9ROR 3.0 · calibrated p 0.638 | 2.8 EB05 2.8 · IC025 +1.5 3/3 methods agree vs other Vitamin Cs: PRR 10.0 (9.5–10.5) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.9 · serious PRR 4.5 | NCT01351805: 1728/6,474 (26.7%) on Vitamin C; 1639/6,464 (25.4%) control |
| Asthenia (weakness) | 5,140 | 3.2 3.1–3.3ROR 3.3 · calibrated p 0.537 | 3.1 EB05 3.1 · IC025 +1.6 3/3 methods agree vs other Vitamin Cs: PRR 7.8 (7.5–8.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.7 · serious PRR 3.4 | not reported in cached trials |
| Vomiting | 4,828 | 2.4 2.3–2.4ROR 2.5 · calibrated p 0.832 | 2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree vs other Vitamin Cs: PRR 7.9 (7.5–8.2) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.3 · serious PRR 2.9 | not reported in cached trials |
| Pruritus (itching) | 4,348 | 2.7 2.6–2.7ROR 2.7 · calibrated p 0.716 | 2.6 EB05 2.6 · IC025 +1.4 3/3 methods agree vs other Vitamin Cs: PRR 8.7 (8.3–9.1) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.5 · serious PRR 4.0 | not reported in cached trials |
| Malaise (feeling unwell) | 4,077 | 2.1 2.1–2.2ROR 2.2 · calibrated p 0.955 | 2.1 EB05 2.1 · IC025 +1.0 3/3 methods agree vs other Vitamin Cs: PRR 9.5 (9.0–10.0) | No label text to screen label has no adverse-reaction text | age-adj. PRR 2.1 · serious PRR 2.7 | not reported in cached trials |
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 Vitamin C?
In FDA FAERS, the most frequently co-reported reaction terms for Vitamin C are fatigue, headache, pain, nausea, diarrhoea, 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 Vitamin C have an FDA boxed warning?
No. The FDA label retrieved for Vitamin C has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Vitamin C 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 496e7d41-2176-7b0c-e063-6394a90a98f1, effective 20260128; matched on
openfda.generic_name.exact:"VITAMIN C") - PubChem CID 54670067 description (ChEBI)
- 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, 1,200 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
VITAMIN C, 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.