Is pelargonium (UMCKALOABO) hepatotoxic? A 46-year old man, who treated his migraine attacks with ibuprofen for years (DOLORMIN EXTRA etc.), took the pelargonium root extract UMCKALOABO (a-t 2003; 34: 28-9) for a few days because of a flu-like infection. Few days later he complained of malaise and of shoulder and back pain. He was referred to the hospital with raised bilirubin and liver enzyme levels. In the following days, the AST rose to 1,064 U/l and the ALT to 1,716 U/l. Histology showed eosinophilic hepatocyte necrosis and slight intracellular cholestasis. After excluding a viral cause, toxic liver cell damage was suspected. A second liver biopsy was done seven weeks later as the patient was still in poor health and early periportal fibrosis was found (NETZWERK report 13.998). Another report on hepatitis (Bundesinstitut für Arzneimittel und Medizinprodukte: letters of 9th and 24th March 2006) and two NETZWERK reports of elevated liver enzymes after self-medication with UMCKALOABO (13.138, 13.705) raised the suspicion that the herbal product may be hepatotoxic. The extract of a South African geranium variety contains coumarins, which are potentially toxic to the liver (SCHMITZ, W. in SCHWABE, U., PAFFRATH, D. [eds.]: "Arzneiverordnungs-Report 1998", Springer, Berlin, Heidelberg 1999, page 80-1). Hepatitis has been described several times in treatment of varicose veins due to the coumarin-containing preparation VENALOT (no longer on the market; a-t 1994; no. 1: 15 and 1998; no. 12: 116). If the suspicion is confirmed, pelargonium, after greater celandine [Chelidonium majus] (a-t 2005; 36: 68) and kava-kava (a-t 2002; 33: 21-2, no longer on the drug market), will be another herbal preparation whose hepatotoxic potential is recognised only after years of mass use.