When first developed, synthetic hormones were well received because they provided some of the benefits of hormone replacement: controlling the symptoms of menopause and fighting osteoporosis and heart disease. However, long term results have shown that synthetic hormones sometimes elicit a negative metabolic response. Some women can’t tolerate synthetic hormones-often suffering side effects such as boating, bleeding or mood swings. In some patients, synthetic estrogens and progestins contributed to the development of breast and uterine cancer. Synthetic hormones are not a perfect match in the body. Synthetic hormones produce abnormal metabolites that can cause side effects and increase the risk of cancer. A natural hormone is a perfect fit in the body-it is a biologically identical hormone replacement.