SAMe is a molecule that is formed naturally in the body. It can also be made in the laboratory. SAMe is involved in the formation, activation, or breakdown of other chemicals in the body, including hormones, proteins, phospholipids, and certain drugs.

SAMe has been available as a dietary supplement in the US since 1999, but it has been used as a prescription drug in Italy since 1979, in Spain since 1985, and in Germany since 1989.

SAMe is used by mouth for depression, anxiety, heart disease, fibromyalgia, abdominal pain, osteoarthritis, bursitis, tendonitis, chronic lower back pain, dementia, Alzheimer's disease, slowing the aging process, chronic fatigue syndrome (CFS), improving mental performance, liver disease, and Parkinson's disease. It is also used for attention deficit-hyperactivity disorder (ADHD), multiple sclerosis, spinal cord injury, seizures, migraine headache, lead poisoning, to break down a chemical in the body called bilirubin, or to help with disorders related to the buildup of a chemical called porphyrin or its precursors.