The Client Is Being Treated with Ketoconazole

The client is being treated with ketoconazole. He tells the nurse that he frequently self-medicates with echinacea. The highest priority instruction that the nurse should give the client is that the combination of the two medications:

A) should enhance the action of the ketoconazole.
B) should diminish the action of the ketoconazole.
C) may result in hepatotoxicity developing.
D) may result in nephrotoxicity developing.