For example, some studies have shown that kava kava, an herb that has been used to help with stress and anxiety, may cause liver damage.Vitamins can also have unwanted effects in your body.
Tell your doctor if you're taking any dietary supplements, no matter how safe you think they are. Even though there may be ads or claims that something has been used for years, they do not prove that it's safe or effective.
Supplements do not have to be approved by the federal government before being sold to the public. Therefore, it's up to consumers to decide what is best for them.
NCI and the National Center for Complementary and Integrative Health (NCCIH) are currently sponsoring or cosponsoring various clinical trials that test CAM treatments and therapies in people.
NCI provides evidence-based PDQ information for many CAM therapies in versions for both the patient and health professional.
Some CAM therapies have undergone careful evaluation and have found to be safe and effective.
However there are others that have been found to be ineffective or possibly harmful.Less is known about many CAM therapies, and research has been slower for a number of reasons: CAM therapies need to be evaluated with the same long and careful research process used to evaluate standard treatments.Standard cancer treatments have generally been studied for safety and effectiveness through an intense scientific process that includes clinical trials with large numbers of patients.CAM therapies include a wide variety of botanicals and nutritional products, such as dietary supplements, herbal supplements, and vitamins.Many of these "natural" products are considered to be safe because they are present in, or produced by, nature. In addition, some may affect how well other medicines work in your body. John's wort, which some people use for depression, may cause certain anticancer drugs not to work as well as they should.Herbal supplements may be harmful when taken by themselves, with other substances, or in large doses.