Can milk thistle be taken with Western Medicine? As milk thistle has a significant effect on the liver, some drugs linked to the action of the P450 enzyme system, such as amitriptyline(Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex) Diclofenac(Voltaren), Fluvastatin (Lescol), Glipizide (Glucotrol), Ibuprofen (Advil),Irbesartan (Avapro), Losartan (Cozaar), Phenytoin (Dilantin), PiroxicamFeldene, Nolvadex, Tolinase, Demadex, Coumadin, etc. are not suitable to be consumed with milk thistle