NutriStack
Bromelain and Warfarin, a caution.
Bromelain, a proteolytic enzyme from pineapple stem, inhibits platelet aggregation and has been shown to reduce thrombin-, ADP-, and collagen-induced platelet activation in vitro. It also has direct fibrinolytic activity. Combined with warfarin, these effects can additively raise bleeding risk.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Pair type
- Caution
- Evidence (highest tier)
- Emerging
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Emerging evidence
Caution
What is happening. Bromelain, a proteolytic enzyme from pineapple stem, inhibits platelet aggregation and has been shown to reduce thrombin-, ADP-, and collagen-induced platelet activation in vitro. It also has direct fibrinolytic activity. Combined with warfarin, these effects can additively raise bleeding risk.
Mechanism. Bromelain proteases inhibit thrombin- and ADP-induced platelet aggregation, reduce platelet adhesion to endothelium, and have intrinsic fibrinolytic activity. These pharmacodynamic effects add to warfarin's reduction of clotting factor synthesis without necessarily altering the INR.
Recommendation. Avoid bromelain supplements while on warfarin. If you take it for sinus or post-surgical use, tell your anticoagulation clinic, watch for bruising or bleeding, and ask for an INR check within 1-2 weeks.
Sources (2)
- Metzig C, Grabowska E, Eckert K, Rehse K, Maurer HR. Bromelain proteases reduce human platelet aggregation in vitro, adhesion to bovine endothelial cells and thrombus formation in rat vessels in vivo. In Vivo. 1999;13(1):7-12. PMID 10218125
- Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm. 2000;57(13):1221-7. PMID 10902065
Stack Score
How this pair moves the number.
Effect on the composite score
If both Bromelain and Warfarin are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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