The short answer
A small, older study found a reversible serum-folate binding change during several days of high-dose aspirin in one healthy participant. It does not establish that people taking typical 81 mg or 100 mg preventive aspirin need routine folic acid, blood testing, or a dosing interval. Keep folic acid that was prescribed for a separate reason unless the prescriber advises a change.
What this answer covers
The direct study used 650 mg aspirin by mouth every 4 hours for three days, not preventive low-dose aspirin and not folic-acid co-use.
- Supplement or preparation
- Folic acid
- Medication ingredient
- aspirin
What the study actually measured
The study followed one healthy woman through the same 11-day protocol twice. She took 650 mg of aspirin by mouth every four hours during the middle three days. Her total and protein-bound serum folate fell and later returned toward baseline. This was a measurement of endogenous folate during a short, high-dose exposure, not a trial of folic-acid supplements.
Why this does not create a universal folic-acid rule
The participant did not receive folic acid as a co-treatment, and the study did not test whether a supplement prevents a clinically important outcome. Urinary folate rose slightly but the abstract calls that change not significant. One repeated protocol cannot show that every aspirin user needs more folic acid or needs a different schedule.
Low-dose prevention is a different exposure
The study aspirin regimen was 650 mg every four hours, far above 81 mg or 100 mg daily preventive use. The retrieved evidence does not show that the measured binding change transfers to those lower regimens. It also does not diagnose folate deficiency or establish how long an effect would persist during ordinary aspirin use.
Practical next step
Do not start, stop, or move folic acid solely to create a gap from aspirin based on this study. If folic acid was prescribed for pregnancy planning, documented deficiency, or another reason, preserve that plan and ask the clinician who manages it before changing it. A personal testing decision should reflect the reason for concern, not an assumed aspirin rule.
Evidence and practical considerations
Timing & monitoring
Evidence is insufficient to establish a routine altered folic-acid requirement or a dosing interval with aspirin.
- Exact scope
- Folic acid; no direct co-use regimen was studied. with Aspirin; direct evidence is limited to 650 mg every 4 hours for three days.
- Medication form and route
- oral aspirin in the small high-dose protocol
- Timing or duration
- Three aspirin-exposure days within an 11-day repeated protocol.
What remains uncertain
- One participant, no folic-acid co-use study, no deficiency outcome, and no 81 mg or 100 mg aspirin evidence.
Factors that may matter: a separately prescribed folic-acid indication; aspirin dose and duration; dietary intake.
Read the supporting source summaries
Source 1: human pharmacology study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One healthy woman who completed an 11-day protocol twice.
Total and bound serum folate fell briskly, significantly, and reversibly; urinary folate rose slightly but not significantly. In vitro aspirin displaced bound serum folate.
How this applies: Direct aspirin-folate measurement only. It does not establish folic-acid dosing, separation, or an effect at 81 mg or 100 mg aspirin.
n=1, high short-term aspirin exposure, no folic-acid co-use arm, no clinical deficiency endpoint, and no preventive-dose comparison.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Private exact-pair package prepared from the root-adjudicated source extraction; no clinical approval recorded. | |
| Research summary published |
Article revision: 93059d5fa31bfba5
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.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.