The short answer
Do not add willow bark to diflunisal without medical advice. This is a relevant NSAID co-use precaution, although the exact added bleeding risk has not been measured.
What this answer covers
Oral medicinal willow bark preparations with prescription oral diflunisal. Salix species, salicin content and combination ingredients may vary.
- Supplement or preparation
- Willow Bark
- Medication ingredient
- diflunisal
The monograph advises medical review
The final European willow bark monograph advises against combining defined willow products with salicylates or other NSAIDs without medical advice. Diflunisal is an NSAID, so this precaution is relevant even though the exact combination’s bleeding rate has not been measured.
Willow and diflunisal are not aspirin
Willow bark contains salicin-related compounds, while diflunisal has its own pharmacology and is not metabolized to salicylic acid. Its platelet effect is reversible and dose-dependent. Evidence about aspirin cannot establish the same quantitative effect for either product or their combination.
Avoid adding a second pain product without a plan
Show your prescriber the willow species, extract, salicin content and other ingredients before adding it for pain. The monograph also cautions against use in active peptic ulcer or NSAID hypersensitivity. Ask for a pain-management plan suited to your history rather than treating botanical products as interchangeable.
Recognize the medicine’s own warning signs
Diflunisal can cause serious stomach or intestinal bleeding even without a supplement. Seek urgent care for vomiting blood or black, tarry stools, and report persistent stomach pain or unusual bleeding. A few hours of separation has not been shown to prevent a combined bleeding effect. Tell your prescriber about other pain relievers, aspirin and anticoagulants.
Evidence and practical considerations
Side effects & toxicity
A measured increase in bleeding specifically from willow bark with diflunisal has not been established.
- Exact scope
- Oral medicinal willow bark preparations with prescription oral diflunisal. Salix species, salicin content and combination ingredients may vary. with Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
- Medication form and route
- Oral
What remains uncertain
- No exact-pair trial identified; monograph advice is precautionary and preparation-specific.
Factors that may matter: Exact preparation and dose; Fasting versus fed dosing; Bleeding and ulcer history; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Prescription oral diflunisal users and healthy-volunteer pharmacology studies.
Diflunisal has dose-dependent reversible platelet effects. At 500 mg twice daily effects were slight; 250 mg twice daily had no measurable effect in a short study. Serious GI bleeding and ulcers remain labeled risks. Antacids may lower levels, especially with continuous use.
How this applies: Exact current drug label. Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
Not proof of each supplement combination. Short healthy-volunteer fecal blood-loss findings do not establish long-term GI safety. Aspirin has different platelet pharmacology. No universal antacid separation interval.
Source 2: Final regulatory herbal monograph
ema.europa.eu · Source check Sep 10, 2026
Population: Users of defined medicinal willow bark preparations.
Concomitant use with salicylates or other NSAIDs is not recommended without medical advice; active peptic ulcer and NSAID hypersensitivity are contraindications.
How this applies: Direct regulatory NSAID co-use precaution, not measured pair incidence.
No exact diflunisal bleeding trial. Coumarin warning is not evidence that diflunisal is a coumarin. Unspecified willow products may differ.
Source 3: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology record.
Diflunisal, IN.
How this applies: Exact identity.
No clinical evidence.
Research assessment: · Open full citations ↗
Side effects & toxicity
Willow bark should not be combined with diflunisal without medical advice.
- Exact scope
- Oral medicinal willow bark preparations with prescription oral diflunisal. Salix species, salicin content and combination ingredients may vary. with Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
- Medication form and route
- Oral
What remains uncertain
- Final monograph explicitly cautions against unsupervised NSAID co-use; this does not quantify bleeding or make willow equivalent to aspirin.
Factors that may matter: Exact preparation and dose; Fasting versus fed dosing; Bleeding and ulcer history; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Prescription oral diflunisal users and healthy-volunteer pharmacology studies.
Diflunisal has dose-dependent reversible platelet effects. At 500 mg twice daily effects were slight; 250 mg twice daily had no measurable effect in a short study. Serious GI bleeding and ulcers remain labeled risks. Antacids may lower levels, especially with continuous use.
How this applies: Exact current drug label. Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
Not proof of each supplement combination. Short healthy-volunteer fecal blood-loss findings do not establish long-term GI safety. Aspirin has different platelet pharmacology. No universal antacid separation interval.
Source 2: Final regulatory herbal monograph
ema.europa.eu · Source check Sep 10, 2026
Population: Users of defined medicinal willow bark preparations.
Concomitant use with salicylates or other NSAIDs is not recommended without medical advice; active peptic ulcer and NSAID hypersensitivity are contraindications.
How this applies: Direct regulatory NSAID co-use precaution, not measured pair incidence.
No exact diflunisal bleeding trial. Coumarin warning is not evidence that diflunisal is a coumarin. Unspecified willow products may differ.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Research summary published |
Article revision: aaebff51632c92d9
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.