Are there any known interactions with CBD oil and medications?

YES !!! CBD HAS A DIRECT EFFECT ON THE LIVER ENZYME P450 ! This enzyme breaks down most time releases medications, ESPECIALLY WARFARIN ( Coumadin) !
You can minimize the interaction by starting your CBD at the lowest level (1 drop), and increasing the dose by just one drop a day, until you get to the dose you want. It’s also important to keep at least 4 hours between when you take your medication and the CBD. The more time you put between the two the better! The good news is that the effects of the interaction between CBD and at least warfarin will lesson with time. CBD can cause a dramatic increase in the INR that could lead to hemorrhages. I experienced a cerebral hemorrhage that led to a hole having to be drilled in my skull to relieve the pressure! If the source of your CBD doesn’t warn you of this interaction, go to a place that does. More than likely those that don’t warn you is trying to sell you who knows what, but it probably doesn’t contain any CBD anyway!

"Yes. CBD inhibits the cytochrome P450 enzyme, which is involved in metabolizing many drugs. ... By inhibiting cytochrome P450, CBD can either reduce or increase the effects of other drugs." "it may be advisable for a physician to monitor a patient's blood levels of other medications while taking CBD." Source: projectcbd