Modern medicine, or medicine as we know it, made rapid progress in identifying, preventing and treating illnesses. Prescription medicines and advances in medical treatment have helped people avoid disability caused by diseases, lowered overall treatment costs, and have lowered death rates for heart disease, stroke, cancer, and other deadly diseases for several decades. Meanwhile, complementary and alternative medicine (CAM) provides natural and effective protection for those who suffer from chronic illness. CAM is defined as a category of medicine that includes a variety of treatment approaches that fall outside the realm of conventional medicine, including Ayurvedic medicine, Sino-Japanese traditional medicine, herbal medicine, qigong therapy, vibration therapy, etc. There is a general scientific consensus that CAM lacks the requisite scientific validation, and their effectiveness is either unproved or disproved. Many of the claims regarding the efficacy of CAM are controversial, since research on them is frequently of low quality and methodologically flawed. However, there are some studies assessing the effect of chronic conditions of various diseases on use of CAM. CAM may also contribute to improved health care utilization and patient outcomes. Although CAM has different advantages and disadvantages from those of modern medicine, it should be effective in finding appropriate methods using the framework of evidence-based medicine (EBM). For example, studies in which a conventional treatment is supplemented with a CAM technique would be valid if compared to the same conventional treatment supplemented with a placebo. As clinical practice guidelines and life-style recommendations for multimorbid patients continue to be developed to include CAM, future research on these and other comorbidities may contribute to improved health care utilization and patient outcomes.