Book excerpt: "Astragalus root. Ginseng. Lavender. Milk thistle. Watercress. These are just a few of the thousands of herbal and natural substances that are believed to have medicinal or healing properties. Do homeopathic therapies and herbal supplements really work as claimed? While it is commonly believed that all herbs are healthy and useful, some herbs have the potential to harm, especially when used in conjunction with certain medications.