The answer is – depending. Herbal medicine can interact with drug therapy. However, many of the supplements that are nutritionally based can be used. There are some exceptions however to this like Vitamin K can interfere with blood thinning medications. It is imperative that you consult with a practitioner who has this knowledge. Many times there can be an enhancement using supplements and drugs; sometimes there is danger in using them together. A safer modality is homeopathy. It is a very safe medicine, however, drugs can render these remedies useless in some circumstances.
Working with a knowledgeable practitioner is key to using herbal medicines, vitamin and mineral therapy, and pharmaceutical treatments safely.