Interaction between warfarin and the herbal product quilinggao.

OBJECTIVE

To describe a patient with loss of anticoagulation control and bleeding after consumption of the combination herbal product quilinggao.

METHODS

A 61-year-old man who was stable on warfarin therapy regularly consumed a jelly-like herbal product called quilinggao ("essence of tortoise shell"). Five days after the daily consumption of a second brand of quilinggao, he developed easy gum bleeding, epistaxis, and skin bruising with an international normalized ratio (INR) >6.0. Warfarin therapy was temporarily withdrawn until the INR decreased to 1.9. On the day of hospital discharge, he took a third brand of quilinggao against medical advice. Three days later, his INR was 5.2. Warfarin therapy was again temporarily withheld and the patient counseled about an apparent herb-warfarin interaction. He could not remember the name of the third brand of quilinggao.

CONCLUSIONS

Quilinggao is a very popular Chinese herbal product. There are many different brands, and the composition of herbal products varies between manufacturers. Chuanbeimu (Fritillaria cirrhosa) in the first brand and beimu (Fritillaria spp.), chishao (Paeoniae rubra, Chinese peony), jinyinhua (Lonicera japonica), and jishi (Poncirus trifoliata) in the second brand of quilinggao have antiplatelet and/or antithrombotic effects. Loss of anticoagulation control occurred after consumption of the second and third brands of quilinggao, possibly due to the presence of a greater number of interacting herbs. An objective causality assessment revealed that the observed reaction was highly probable to be related to the ingestion of the second and third brands of quilinggao.

CONCLUSIONS

Quilinggao contains herbal ingredients that can interact with warfarin. Patients on warfarin therapy should be discouraged from taking herbal medicines, especially preparations that are already known to have antiplatelet and antithrombotic effects.