Background: Herbal supplements are commonly used, however, their side-effect profiles are poorly understood and not subject to the same scrutiny as prescribed medications. Some herbal supplements such as St Johns' Wort are accepted to interfere with clotting pathways, however others, including Red Clover have theoretical bleeding risks based on coumarin content with very little underlying evidence.
Case description: This case reports a 65-year-old woman who suffered a spontaneous acute-on-chronic subdural hemorrhage with a significant postoperative re-hemorrhage. She had no other risk factors for coagulopathy other than a history of taking Red Clover supplements for postmenopausal symptoms. Her normal INR combined with an intraoperative thromboelastogram confirmed a coagulopathy which was more consistent with anti-platelet effects than coumarin toxicity. After tranexamic acid and platelet transfusions she had no further bleeding and made an uneventful recovery.
Conclusion: This case highlights another risk factor for intracranial hemorrhage and the importance of a thorough drug history. The mechanism of Red Clover induced coagulopathy appears to be mediated through anti-platelet actions, which is consistent with in-vitro evidence reporting its role in preventing platelet adhesion.
Keywords: Herbal supplements; red clover; subdural hematoma.