Severe drug induced acute hepatitis associated with use of St John's wort (Hypericum perforatum) during treatment with pegylated interferon α.

A 61-year-old woman with chronic hepatitis C received peginterferon α 180 μg/week, and obtained undetectable qualitative hepatitis C virus (HCV) RNA (lower limit of detection 50 IU/ml) after 8 weeks of treatment. Shortly thereafter aminotransferase values greatly increased (>20 × upper limit of normal) and did not decline after treatment suspension. The patient admitted taking St John's wort (Hypericum perforatum) for depressed mood, recommended by a friend, during the preceding 6 weeks. Liver function tests continued to worsen and international normalised ratio (INR) prolongation developed; the patient was hospitalised. Test for antinuclear antibody was positive (1:320) and treatment with methylprednisolone was started; bilirubin and aminotransferase levels slowly declined, though a new flare occurred when steroids were tapered. After 6 months of prednisone treatment, the liver function tests returned to baseline levels. The combination of peginterferon α and St John's wort resulted in a severe acute hepatitis in this patient. Patients should be advised of this potential toxic effect of this herbal remedy.