Keywords: case report; delayed-type hypersensitivity; drug patch testing; St. John's wort EN case report delayed-type hypersensitivity drug patch testing St. John's wort 381 383 3 09/08/22 20221001 NES 221001 St. John's wort ( I Hypericum perforatum i ) is a wild flowering plant and its extracts have been used for centuries to treat mental health problems including low mood, depression and anxiety.1 Side effects and drug interactions are commonly seen, as it is well-known to induce the liver enzyme CYP3A4.2 True allergic or hypersensitivity reactions to St. John's wort, are less well-described and rarely reported.3,4 Here, we report a novel case of delayed-type hypersensitivity to St. John's wort extract tablets, confirmed by patch testing. DISCUSSION Here, we describe a novel case of St. John's wort extracts tablet-induced delayed-type hypersensitivity confirmed by patch testing. Delayed-type hypersensitivity reaction to St. John's wort extract confirmed by patch testing. [Extracted from the article]