In the news currently is an article about the potential harm of taking aspirin to prevent a heart attack or stroke. An analysis of more than 100,000 patients, published in Archives of Internal Medicine, concluded the risk of internal bleeding was too high to take routinely in healthy people. The UK-led study said only people with a history of heart problems or stroke should take the tablets.

Aspirin prevents blood clots from forming by preventing platelets from sticking together and therefore can be of use in people who have had heart attacks or strokes.

However, there are safer ways of reducing the tendency of the blood to clot in the form of a wide variety of herbs, which act via a wide range of mechanisms. Although there is no evidence of commonly used herbs causing internal bleeding, it is important to avoid their use in those individuals on medications such as aspirin, warfarin, heparin or any others that affect blood clotting. They should also be avoided if clotting or platelet levels are sub-optimal.

Gingko biloba is a herb commonly associated with improving cognitive function in aging and part of its action is as an anti-platelet-activating factor (anti-PAF) agent (see Dubey et al., 2004). PAF is produced by a wide variety of cells and causes platelet aggregation (as well as other biological effects such as bronchoconstriction and inflammation). A study on use in elderly patients showed no significant increase in bleeding time (Halil et al., 2005). In addition, Gingko may also have fibrinolytic properties, aiding breakdown of clots once formed (Naderi et al., 2005).

Although most research is available for Gingko, there are many other herbs that have an effect on blood clotting, some of which have a limited amount of pre-clinical scientific evidence associated with them. Angelica sinensis has been shown to have an anti-platelet effect (Lo et al., 1995; Naderi et al., 2005; Yang et al., 2002; Zhang et al., 2009), Salvia miltorrhizia was shown in a randomised placebo-controlled trial (Sun et al., 2009) to increase absorption of intracranial haematoma and reduced indicators of clotting (plasma fibrinogen and D-dimer). However this study involved intravenous administration of the extract. Other herbs used for their anticoagulant effect are ginger (Zingiber officinalis), chilli (Capsicum annuum), hawthorn (Crataegus spp.), garlic (Alllium sativum), bladderwrack (Fucus vesiculosus) and fish oils may also be beneficial.

Other supplements may suppport vitamin K (which is necessary in clotting) including high doses of vitamin E (vitamin K antagonist), alfalfa (high vitamin K content) and co-enzyme Q10 (vitamin K-like activity) (Mousa, 2010)

Caution: The information here is offered for its educational value only and should not be used to diagnose, treat, or prevent disease; please contact your health care practitioner.


Dubey AK, Shankar PR, Upadhyaya D, Deshpande VY. (2004)  ‘Ginkgo biloba–an appraisal’.  Kathmandu Univ Med J (KUMJ). 2(3):225-9

Halil M, Cankurtaran M, Yavuz BB, Ozkayar N, Ulger Z, Dede DS, Shorbagi A, Buyukasik Y, Haznedaroglu IC, Arogul S. (2005) No alteration in the PFA-100 in vitro bleeding time induced by the Ginkgo biloba special extract, EGb 761, in elderly patients with mild cognitive impairment. Blood Coagul Fibrinolysis. 16(5):349-53.

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Naderi GA, Asgary S, Jafarian A, Askari N, Behagh A, Aghdam RH. (2005) Fibrinolytic effects of Ginkgo biloba extract. Exp Clin Cardiol. 10(2):85-7.

Sun M, Zhang JJ, Shan JZ, Zhang H, Jin CY, Xu S, Wang YL.2009 Clinical observation of Danhong Injection (herbal TCM product from Radix Salviae miltiorrhizae and Flos Carthami tinctorii) in the treatment of traumatic intracranial hematoma.Phytomedicine. Aug;16(8):683-9.

Yang T, Jia M, Mei Q, Shang P.2002 Effects of Angelica polysaccharide on blood coagulationand platelet aggregation].Zhong Yao Cai. May;25(5):344-5. Chinese.

Zhang L, Du JR, Wang J, Yu DK, Chen YS, He Y, Wang CY.2009 Z-ligustilide extracted from Radix Angelica Sinensis decreased platelet aggregation induced by ADP ex vivo and arterio-venous shunt thrombosis in vivo in rats.Yakugaku Zasshi. Jul;129(7):855-9.