If you are taking herbal remedies as a part of your daily routine, it may be in your best interest to stop taking them two weeks before an invasive body modification procedure (it's probably not an issue for things like piercings, but do let your piercer know) to avoid herbal interactions—some herbs will interact with body modification procedures if taken in significant quantity.
Most common are herbs that act as blood thinning agents such as garlic, ginger, gingko bilboa, feverfew, alfalfa, clove, dong quai, danshen, ginseng, and so on, but a small number, including agrimony, goldenseal, mistletoe, and yarrow can act as coagulants.
In addition, some herbs such as kava kava, St. John's Wort, and valerian can interact (and intensify or prolong) the effects of narcotic analgesics. Herbs like capsicum may increase the absorption of some sedatives. Finally, substances such as ephedra, caffeine, and common street drugs may greatly increase the perception of pain during a procedure and are strongly recommended against.