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Aspirin side effects: what 533,828 FDA adverse event reports show

Aspirin · Cardiaspirin Protect · 1,169 reaction terms · 1,989,715 drug–reaction co-reports · data 2026-09-14
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Drug class

Nonsteroidal Anti-inflammatory Drug, Platelet Aggregation Inhibitor

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Cardiaspirin Protect

openFDA label

Who reports

533,828 reports · 71% serious · 48,985 with death outcome · 49% female

openFDA FAERS counts, all years, deduplication not applied

Used for

ftemporarily relief of minor aches and pains or as recommended by your doctor. Because of its delayed release action, this product will not provide fast relief of headache or symptoms needing immediate relief.

FDA label, Indications and Usage

What it is

Acetylsalicylic acid is a member of the class of benzoic acids that is salicylic acid in which the hydrogen that is attached to the phenolic hydroxy group has been replaced by an acetoxy group.

PubChem CID 2244 (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 1Lab value / disease marker 1Not in label — unassessed 38
What the badges mean

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. 1,129 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show:
ReactionReportsPRR 95% CI · ROR · χ²/pEBGM EB05 · IC025Label screenSerious-only & strataTrial cross-check
Chronic kidney disease-mineral and bone disorder34918.5
16.2–21.0ROR 18.5 · χ² 3,859 / p <1e-300
12.7 EB05 11.6 · IC025 +3.5
3/3 methods agree
Not in label — unassessedserious n=349 · ♀ 0% (drug 49%)not reported in cached trials
Nephrogenic anaemia1,44217.2
16.1–18.3ROR 17.2 · χ² 15,070 / p <1e-300
12.1 EB05 11.6 · IC025 +3.5
3/3 methods agree
Not in label — unassessedserious n=1,441not reported in cached trials
Hyperparathyroidism secondary76016.5
15.1–18.0ROR 16.5 · χ² 7,684 / p <1e-300
11.8 EB05 11.1 · IC025 +3.4
3/3 methods agree
Not in label — unassessedserious n=759NCT01776424: 1/9,134 (0.0%) on Aspirin (serious AE)
Vascular stent thrombosis59015.7
14.3–17.3ROR 15.7 · χ² 5,727 / p <1e-300
11.4 EB05 10.6 · IC025 +3.4
3/3 methods agree
Not in label — unassessedserious n=589 · ♀ 0% (drug 49%) · 100% cliniciannot reported in cached trials
Diverticulum intestinal haemorrhagic48910.6
9.6–11.7ROR 10.6 · χ² 3,299 / p <1e-300
8.4 EB05 7.8 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious n=488NCT01776424: 1/9,134 (0.0%) on Aspirin (serious AE)
Coronary artery stenosis1,06910.3
9.6–11.0ROR 10.3 · χ² 7,054 / p <1e-300
8.3 EB05 7.9 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious n=1,062not reported in cached trials
Angina unstable1,37210.1
9.6–10.8ROR 10.2 · χ² 8,911 / p <1e-300
8.2 EB05 7.8 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious n=1,365not reported in cached trials
Haemorrhagic anaemia9129.9
9.2–10.6ROR 9.9 · χ² 5,751 / p <1e-300
8.0 EB05 7.6 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious n=912not reported in cached trials
Carotid artery stenosis6949.5
8.7–10.3ROR 9.5 · χ² 4,188 / p <1e-300
7.7 EB05 7.3 · IC025 +2.8
3/3 methods agree
Not in label — unassessedserious n=690NCT01776424: 2/9,107 (0.0%) on Aspirin; 2/9,109 (0.0%) control (serious AE)
Lower gastrointestinal haemorrhage1,4579.4
8.8–9.9ROR 9.4 · χ² 8,720 / p <1e-300
7.7 EB05 7.4 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious PRR 6.2NCT01776424: 1/9,107 (0.0%) on Aspirin; 2/9,109 (0.0%) control (serious AE)
Thrombosis in device6469.3
8.5–10.1ROR 9.3 · χ² 3,831 / p <1e-300
7.6 EB05 7.1 · IC025 +2.8
3/3 methods agree
Not in label — unassessedserious n=642 · 100% cliniciannot reported in cached trials
Coronary artery disease5,9179.2
9.0–9.5ROR 9.3 · χ² 34,915 / p <1e-300
7.6 EB05 7.4 · IC025 +2.9
3/3 methods agree
Not in label — unassessedserious PRR 6.2NCT01776424: 1/9,134 (0.0%) on Aspirin; 1/9,109 (0.0%) control (serious AE)
Ischaemic cardiomyopathy5989.2
8.4–10.0ROR 9.2 · χ² 3,497 / p <1e-300
7.5 EB05 7.0 · IC025 +2.8
3/3 methods agree
Not in label — unassessedserious n=599 · ♀ 0% (drug 49%)not reported in cached trials
Rebound acid hypersecretion5819.0
8.2–9.8ROR 9.0 · χ² 3,315 / p <1e-300
7.4 EB05 6.9 · IC025 +2.7
3/3 methods agree
Not in label — unassessedserious n=581not reported in cached trials
Aortic valve stenosis3388.9
7.9–10.1ROR 8.9 · χ² 1,918 / p <1e-300
7.4 EB05 6.7 · IC025 +2.7
3/3 methods agree
Not in label — unassessedserious n=338 · ♀ 100% (drug 49%) · 100% cliniciannot reported in cached trials
Upper gastrointestinal haemorrhage3,1538.8
8.5–9.2ROR 8.9 · χ² 17,704 / p <1e-300
7.3 EB05 7.1 · IC025 +2.8
3/3 methods agree
Not in label — unassessedserious PRR 5.9NCT01776424: 1/9,107 (0.0%) on Aspirin; 2/9,109 (0.0%) control (serious AE)
Coronary arterial stent insertion9058.3
7.8–9.0ROR 8.4 · χ² 4,788 / p <1e-300
7.0 EB05 6.6 · IC025 +2.7
3/3 methods agree
Not in label — unassessedserious n=898not reported in cached trials
Diastolic dysfunction5508.3
7.5–9.1ROR 8.3 · χ² 2,874 / p <1e-300
6.9 EB05 6.4 · IC025 +2.6
3/3 methods agree
Not in label — unassessedserious n=544 · 100% cliniciannot reported in cached trials
Coronary artery occlusion2,3868.0
7.7–8.4ROR 8.1 · χ² 12,102 / p <1e-300
6.8 EB05 6.6 · IC025 +2.7
3/3 methods agree
Not in label — unassessedserious PRR 5.5not reported in cached trials
Essential hypertension4437.9
7.1–8.8ROR 7.9 · χ² 2,205 / p <1e-300
6.7 EB05 6.2 · IC025 +2.6
3/3 methods agree
Not in label — unassessedserious n=413not reported in cached trials
Coronary artery thrombosis3437.8
7.0–8.8ROR 7.8 · χ² 1,683 / p <1e-300
6.6 EB05 6.0 · IC025 +2.5
3/3 methods agree
Not in label — unassessedserious n=341 · ♀ 0% (drug 49%) · 100% cliniciannot reported in cached trials
Retroperitoneal haemorrhage4127.7
6.9–8.5ROR 7.7 · χ² 1,980 / p <1e-300
6.5 EB05 6.0 · IC025 +2.5
3/3 methods agree
Not in label — unassessedserious n=410 · 100% cliniciannot reported in cached trials
Gastrointestinal haemorrhage13,5827.4
7.3–7.5ROR 7.5 · χ² 62,935 / p <1e-300
6.3 EB05 6.2 · IC025 +2.6
3/3 methods agree
Not in label — unassessedserious PRR 5.1NCT01776424: 1/9,107 (0.0%) on Aspirin; 2/9,109 (0.0%) control (serious AE)
Labelled drug-drug interaction medication error1,4317.3
6.9–7.7ROR 7.3 · χ² 6,535 / p <1e-300
6.3 EB05 6.0 · IC025 +2.6
3/3 methods agree
Reporting / coding artifactserious PRR 5.9not reported in cached trials
Acute myocardial infarction4,7477.3
7.1–7.5ROR 7.4 · χ² 21,712 / p <1e-300
6.3 EB05 6.1 · IC025 +2.6
3/3 methods agree
Not in label — unassessedserious PRR 5.1NCT01776424: 1/9,134 (0.0%) on Aspirin; 1/9,107 (0.0%) control (serious AE)
Duodenal ulcer haemorrhage4437.0
6.3–7.7ROR 7.0 · χ² 1,912 / p <1e-300
6.0 EB05 5.6 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=442 · ♀ 0% (drug 49%)NCT01776424: 1/9,134 (0.0%) on Aspirin (serious AE)
Blood loss anaemia3416.9
6.2–7.8ROR 6.9 · χ² 1,453 / p <1e-300
6.0 EB05 5.4 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=337 · ♀ 0% (drug 49%)not reported in cached trials
Coronary artery bypass8606.7
6.2–7.2ROR 6.7 · χ² 3,536 / p <1e-300
5.8 EB05 5.5 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=859not reported in cached trials
Carotid artery occlusion5376.6
6.0–7.2ROR 6.6 · χ² 2,163 / p <1e-300
5.7 EB05 5.3 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=529not reported in cached trials
Gastric ulcer haemorrhage8196.6
6.1–7.1ROR 6.6 · χ² 3,298 / p <1e-300
5.7 EB05 5.4 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=814NCT01776424: 1/9,134 (0.0%) on Aspirin; 1/9,109 (0.0%) control (serious AE)
Ventricular hypertrophy3626.4
5.7–7.1ROR 6.4 · χ² 1,403 / p <1e-300
5.6 EB05 5.1 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious n=359 · ♀ 0% (drug 49%) · 100% cliniciannot reported in cached trials
Arteriosclerosis coronary artery9406.4
5.9–6.8ROR 6.4 · χ² 3,626 / p <1e-300
5.6 EB05 5.3 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious n=929not reported in cached trials
Orthopnoea4486.3
5.7–6.9ROR 6.3 · χ² 1,692 / p <1e-300
5.5 EB05 5.1 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious n=431not reported in cached trials
Mitral valve incompetence1,5876.2
5.9–6.6ROR 6.3 · χ² 6,000 / p <1e-300
5.5 EB05 5.3 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious PRR 4.5not reported in cached trials
End stage renal disease2,5576.2
5.9–6.4ROR 6.2 · χ² 9,535 / p <1e-300
5.4 EB05 5.3 · IC025 +2.4
3/3 methods agree
Not in label — unassessedserious PRR 4.4NCT01776424: 1/9,107 (0.0%) control (serious AE)
Haemorrhagic stroke1,0896.2
5.8–6.6ROR 6.2 · χ² 4,044 / p <1e-300
5.4 EB05 5.2 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious PRR 4.4NCT00000479: 24/9,966 (0.2%) on Aspirin; 21/9,971 (0.2%) control (serious AE)
Radiculopathy3646.1
5.5–6.9ROR 6.1 · χ² 1,341 / p 7e-294
5.4 EB05 4.9 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious n=360 · ♀ 100% (drug 49%) · 100% clinicianNCT01776424: 1/9,134 (0.0%) on Aspirin (serious AE)
Aortic stenosis4796.1
5.5–6.7ROR 6.1 · χ² 1,757 / p <1e-300
5.4 EB05 5.0 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious n=472NCT01776424: 1/9,107 (0.0%) control (serious AE)
Brain natriuretic peptide increased4176.0
5.4–6.6ROR 6.0 · χ² 1,493 / p <1e-300
5.3 EB05 4.9 · IC025 +2.2
3/3 methods agree
Lab value / disease markerserious n=408 · ♀ 0% (drug 49%) · 100% cliniciannot reported in cached trials
Benign prostatic hyperplasia6915.9
5.4–6.4ROR 5.9 · χ² 2,426 / p <1e-300
5.2 EB05 4.9 · IC025 +2.3
3/3 methods agree
Not in label — unassessedserious n=671 · ♀ 0% (drug 49%)NCT01776424: 1/12,903 (0.0%) on Aspirin; 1/9,109 (0.0%) control (serious AE)

Trial evidence (ClinicalTrials.gov)

✓ Trial adverse-event data found on ClinicalTrials.gov

Largest completed trials with posted results that list Aspirin 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 (15 of 40 signal terms matched).

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.

ReactionReportsPRR 95% CI · ROR · χ²/pEBGM EB05 · IC025Label screenSerious-only & strataTrial cross-check
Fatigue (tiredness)33,1771.7
1.7–1.7ROR 1.8 · χ² 9,644 / p <1e-300
1.7 EB05 1.7 · IC025 +0.7Not in label — unassessedserious PRR 1.6not reported in cached trials
Dyspnoea (shortness of breath)28,1242.0
2.0–2.0ROR 2.1 · χ² 13,763 / p <1e-300
2.0 EB05 1.9 · IC025 +0.9Not in label — unassessedserious PRR 1.8NCT01776424: 4/9,107 (0.0%) on Aspirin; 5/9,109 (0.1%) control (serious AE)
Diarrhoea (diarrhea)27,5211.7
1.7–1.7ROR 1.7 · χ² 8,006 / p <1e-300
1.7 EB05 1.7 · IC025 +0.7Not in label — unassessedserious PRR 1.5NCT01776424: 1/12,903 (0.0%) on Aspirin; 5/9,109 (0.1%) control (serious AE)
Nausea27,4611.4
1.4–1.4ROR 1.4 · χ² 2,872 / p <1e-300
1.4 EB05 1.4 · IC025 +0.4Labeled adverse reaction
exact term
serious PRR 1.4NCT01776424: 1/12,903 (0.0%) on Aspirin (serious AE)
Dizziness23,1521.9
1.8–1.9ROR 1.9 · χ² 9,079 / p <1e-300
1.8 EB05 1.8 · IC025 +0.8Not in label — unassessedserious PRR 1.8NCT01776424: 1/12,903 (0.0%) on Aspirin; 2/9,109 (0.0%) control (serious AE)
Drug ineffective (drug did not work)22,5020.7
0.7–0.7ROR 0.7 · χ² 3,984 / p <1e-300
0.7 EB05 0.7 · IC025 -0.6
PRR-only: not supported by EBGM or IC
Reporting / coding artifactserious PRR 0.9not reported in cached trials
Headache20,3191.3
1.3–1.3ROR 1.3 · χ² 1,263 / p 5e-277
1.3 EB05 1.3 · IC025 +0.3Likely indication confounding
term in indications
serious PRR 1.4NCT01776424: 3/9,134 (0.0%) on Aspirin; 3/9,109 (0.0%) control (serious AE)
Off label use (used outside approved label)19,6880.9
0.9–0.9ROR 0.9 · χ² 285 / p 4e-64
0.9 EB05 0.9 · IC025 -0.2
PRR-only: not supported by EBGM or IC
Reporting / coding artifactserious PRR 0.9not reported in cached trials
Asthenia (weakness)19,4972.1
2.1–2.1ROR 2.1 · χ² 10,723 / p <1e-300
2.0 EB05 2.0 · IC025 +1.0
3/3 methods agree
Not in label — unassessedserious PRR 1.8NCT01776424: 1/12,903 (0.0%) on Aspirin; 3/9,109 (0.0%) control (serious AE)
Fall19,2212.3
2.3–2.4ROR 2.4 · χ² 14,226 / p <1e-300
2.3 EB05 2.2 · IC025 +1.2
3/3 methods agree
Not in label — unassessedserious PRR 2.0NCT01776424: 2/9,107 (0.0%) control (serious AE)
Pain18,6581.2
1.2–1.2ROR 1.2 · χ² 599 / p 1e-132
1.2 EB05 1.2 · IC025 +0.2Likely indication confounding
term in indications; also in warnings
serious PRR 1.1NCT01776424: 1/12,903 (0.0%) on Aspirin; 4/9,109 (0.0%) control (serious AE)
Pneumonia (lung infection)16,4942.1
2.0–2.1ROR 2.1 · χ² 8,631 / p <1e-300
2.0 EB05 2.0 · IC025 +1.0Not in label — unassessedserious PRR 1.6NCT01776424: 17/12,903 (0.1%) on Aspirin; 21/9,109 (0.2%) control (serious AE)
Vomiting16,4021.4
1.4–1.4ROR 1.4 · χ² 1,745 / p <1e-300
1.4 EB05 1.4 · IC025 +0.4Labeled adverse reaction
exact term
serious PRR 1.4NCT01776424: 2/9,107 (0.0%) on Aspirin; 1/9,109 (0.0%) control (serious AE)
Death15,4070.7
0.7–0.7ROR 0.7 · χ² 2,085 / p <1e-300
0.7 EB05 0.7 · IC025 -0.5
PRR-only: not supported by EBGM or IC
Outcome field, not a reactionserious PRR 0.6NCT01776424: 5/12,903 (0.0%) on Aspirin; 3/9,109 (0.0%) control (serious AE)
Myocardial infarction (heart attack)15,1633.6
3.6–3.7ROR 3.7 · χ² 26,363 / p <1e-300
3.4 EB05 3.3 · IC025 +1.7
3/3 methods agree
Not in label — unassessedserious PRR 2.7NCT01776424: 1/9,134 (0.0%) on Aspirin; 1/9,107 (0.0%) control (serious AE)

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.

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 Aspirin?

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

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

Do FAERS signals prove that Aspirin 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

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.