Cudrania tricuspidata is a deciduous tree belonging to the Moraceae plant, which has been widely used as a folk remedy or health supplements in the Asian countries including Korea. As far as we know, side effects from taking the extract of C. tricuspidata has not yet been reported. We reviewed the electronic medical records of 2 patients who had adverse drug reactions to C. tricuspidata. The first case was a 30-year-old woman without a specific medical history. She was admitted with a 2-week history of jaundice and dyspepsia after taking extract of C. tricuspidata for 3 days. Initial laboratory findings were as follows: aspartate aminotransferase, 364 IU/L; alanine aminotransferase, 574 IU/L; total bilirubin, 36.3 mg/dL; and direct bilirubin, 18.3 mg/dL. She was conservatively treated for liver and renal failure while awaiting liver transplantation. However, she was expired due to combined pneumonia and progressed hepatic and renal failure. The second case was a 42-year-old woman who has chronic urticaria without other medical history. She was admitted with a 3-month history of whole body rash with small pustular vesicle after taking extract of C. tricuspidata. She was treated with intravenous steroids and antihistamines. Skin lesions were improved after 1 week. Here, we report 2 cases of adverse drug reaction to C. tricuspidata. It should be considered that C. tricuspidata ingestion could cause severe adverse drug reactions such as liver failure and acute generalized exanthematous pustulosis.