The short answer
In ASPREE, daily 100 mg aspirin was associated with more incident anemia and lower ferritin than placebo in older adults. This supports considering anemia and iron-status assessment when clinically appropriate. It does not prove the cause of anemia, show that everyone should take iron, or establish an iron-aspirin spacing rule.
What this answer covers
Evidence concerns 100 mg/day aspirin versus placebo in older adults. Iron pills, iron salts, and timing were not tested.
- Supplement or preparation
- Iron
- Medication ingredient
- aspirin
What ASPREE found
ASPREE randomized 19,114 older adults to aspirin 100 mg daily or placebo. Incident anemia was more frequent with aspirin, with a hazard ratio of 1.20 and a 95% confidence interval of 1.12 to 1.29. In the year-three ferritin subset, values below 45 micrograms/L occurred in 13% of aspirin recipients and 9.8% of placebo recipients.
What the result does and does not explain
The study does not determine why an individual develops anemia. It did not adjudicate every cause, and anemia can have many causes besides iron loss. It also did not test an iron supplement, an iron salt, or a dose schedule. The result supports assessment when appropriate, rather than self-diagnosis or automatic replacement.
Bleeding symptoms need prompt attention
The current 81 mg aspirin label warns that aspirin can cause severe stomach bleeding. It specifically names feeling faint, vomiting blood, bloody or black stools, and persistent stomach pain. Those symptoms warrant urgent medical evaluation.
Timing and monitoring
No reviewed study tested whether iron changes aspirin absorption, benefit, or bleeding at a particular interval. No evidence-based separation interval or routine iron-pill plan was identified. A clinician can decide whether a complete blood count, ferritin, dietary assessment, or another cause evaluation is appropriate before recommending replacement.
Evidence and practical considerations
Physiologic interactions
For an older person taking 100 mg/day aspirin, anemia or iron-status assessment may be considered when clinically appropriate; routine iron supplementation and aspirin-iron spacing are not established.
- Exact scope
- Iron status and iron supplements; no iron product was tested. with Oral aspirin 100 mg/day in ASPREE; label context is 81 mg enteric-coated aspirin.
- Medication form and route
- oral aspirin
- Timing or duration
- ASPREE trial follow-up; ferritin subset assessed at year 3.
What remains uncertain
- No cause adjudication, no iron-treatment trial, and no timing evidence.
Factors that may matter: older age; symptoms or signs of gastrointestinal bleeding; other potential causes of anemia.
Read the supporting source summaries
Source 1: randomized trial secondary analysis
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 19,114 older ASPREE participants; ferritin subset 7,139 at year 3.
Incident anemia hazard ratio 1.20 (95% CI 1.12-1.29). At year 3, ferritin below 45 micrograms/L was 13% with aspirin and 9.8% with placebo.
How this applies: Direct low-dose aspirin evidence for anemia and ferritin outcomes, not a directive to take iron.
No cause-of-anemia adjudication, no iron-supplement or timing trial, and population limited to older adults.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Users of this labeled 81 mg enteric-coated aspirin product.
Warns of severe stomach bleeding and names faintness, vomiting blood, bloody or black stools, and persistent stomach pain as warning signs.
How this applies: Medication safety context for a person evaluated for anemia or possible bleeding.
Product-label warning; it does not establish an iron replacement regimen or explain a particular person's anemia.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Private package prepared without clinical approval or release. | |
| Research summary published |
Article revision: 4b3fda3274eacb96
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
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