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Ask Dr. Gourmet

Can I take horse chestnut while on Coumadin (warfarin)?

There seems to be growing evidence that horse chestnut is good for veins, with EBSCO adding that benefits may include "sealing leaking capillaries, improving the elastic strength of veins, preventing the release of enzymes (known as glycosaminoglycan hydrolases) that break down collagen and open holes in capillary walls, decreasing inflammation, and blocking other various physiological events that lead to vein damage." Several studies have tested it for chronic venous insufficiency and varicose veins.

I have mild to moderate post-thrombotic syndrome and don't want it to get any worse. However, I'm on Coumadin for life (or until they come out with better alternatives). Is it possible to take horse chestnut while on Coumadin? Like many drugs, there are warnings the combo could increase bleeding risks.

Dr. Gourmet Says...

horse chestnut

There has been some evidence for horse chestnut being beneficial for vein conditions such as venous insufficiency. Below is an abstract from 2002.

That said, I would want any of my patients using Coumadin (warfarin) to be very careful when adding supplements to their regimen. There's no regulation of the herb and supplement industry and no reporting standards for how these products might interact with pharmaceuticals, so extra caution is called for, not just with Coumadin but with any medication.

Efficacy, routine effectiveness, and safety of horsechestnut seed extract in the treatment of chronic venous insufficiency. A meta-analysis of randomized controlled trials and large observational studies. Int Angiol. 2002 Dec;21(4):305-15.
Siebert U, Brach M, Sroczynski G, Berla K.; Institute of Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians-University of Munich, Germany.


Safe and effective oral therapies for chronic venous insufficiency (CVI) would provide an important alternative to mechanical compression treatment. Several narrative reviews and one systematic review have summarized the efficacy of horse chestnut seed extract (HCSE), but to our knowledge no systematic review has included data from both randomized controlled trials (RCTs) and large-scale observational studies regarding outcomes as well as adverse events.

Using a systematic literature search, we identified 13 RCTs of CVI (1,051 patients) and 3 observational studies (10,725 patients) that met our inclusion criteria. Examined outcomes were leg volume, ankle and calf circumference, edema, pain, sensation of tension, swelling, leg fatigue/heaviness, calf cramps, and itching. Random and fixed effect models were used to pool outcomes and adverse events separately for RCTs and observational studies.

Overall, the RCTs indicated that HCSE improved symptoms in patients with CVI. Compared to placebo, HCSE reduced leg volume by 46.4 ml (95% CI, 11.3-81.4 ml) and increased the likelihood of improvement in leg pain 4.1-fold (95% CI, 0.98-16.8). Similarly, improvement probabilities were increased 1.5-fold (95% CI, 1.2-1.9) for edema and 1.7-fold (95% CI, 0.01-3.0) for itching. There was insufficient evidence to demonstrate HCSE's effect on leg fatigue/heaviness or calf cramps. Observational studies showed significant effectiveness regarding pain, edema, and leg fatigue/heaviness. No severe adverse events were reported, and HCSE did not significantly increase mild adverse events.

Based on meta-analyses of RCTs and observational studies, HCSE appears to be an effective and safe treatment for CVI. Further RCTs and carefully conducted large-scale observational studies are required to evaluate the long-term effectiveness and safety of HCSE in routine settings.

Thanks for writing,

Timothy S. Harlan, MD, FACP, CCMS
Dr. Gourmet