Muscle spasm associated with therapeutic use of Cang Er Zi Wan

Cang Er Zi Wan (CEZW) is a herbal medication derived from Xanthium sibiricum that is used to treat allergies and upper respiratory problems. Its toxicity has been described in grazing animals, in experimental studies, and in human overdoses. We describe a case of muscular spasm that was associated with the therapeutic use of CEZW.

A 17-year-old female was prescribed CEZW for chronic allergies. Shortly after her second dose of 10 pills BID, she developed intermittent muscular spasms. She was seen in an Emergency Department and had normal vital signs and no significant laboratory abnormalities. Her physical exam was significant only for intermittent spasm of the muscles of the face, neck, and upper extremities. No tremor, fasciculation, dystonia, akisthisia, chorea, bradykinesia, or clonus was noted. She discontinued the CEZW and the symptoms slowly decreased over 4 days. Testing of the product did not detect any other medications or drugs.

CEZW is a herbal medication that contains X. sibiricum. X. sibiricum is a widespread weed that has caused muscular spasm, seizures, and death in animals that graze on it as well as animals experimentally exposed to it. Eleven cases of accidental human ingestion of Xanthium leading to spasm, somnolence, hypoglycemia, renal, and liver toxicity have been described. We describe a unique case of isolated muscular spasms because of the therapeutic use of a CEZW product.