It depends. With most western drugs, there will most often be no negative reaction if they are taken one to two hours apart. However, there are some medications that either impact absorption of herbs OR whose absorption is affected by herbs. As such, it is best to inform your Chinese Medicine practitioner of all medications, vitamins, supplements, and herbs that you are taking to avoid adverse interactions. We can work with your doctor to determine appropriate dosages and we can provide pharmaceutical information to him/her.