Medical marijuana contains powerful anti-inflammatory compounds as well as natural analgesics, providing a one-two punch that makes medicinal marijuana an excellent part of an arthritis treatment plan. Medical marijuana can relieve joint pain while at the same time reducing the inflammation that precipitated that pain. Rheumatoid arthritis, osteoarthritis, and even juvenile arthritis may be treated with the help of cannabinoids naturally occurring in marijuana.

27 million Americans have osteoarthritis, the most common form of arthritis. This condition, also known as degenerative joint disease, causes breakdown of joint cartilage resulting in pain and inflammation where bare joints rub together. A further 1.3 million Americans are living with rheumatoid arthritis, an autoimmune condition that causes severe pain. In addition, 300,000 children in America have juvenile arthritis. While most doctors do not recommend use of medical marijuana for young children, adults and older teens can treat their arthritis with medicinal marijuana.

In a 2005 study, THC and cannabidiol were found to produce notable improvements in pain, quality of sleep, and to reduce disease activity in patients with rheumatoid arthritis. Both these compounds are among the cannabinoids naturally occurring in medical marijuana. In 2000, researchers found that cannabidiol "effectively blocked progression of arthritis" in animal trials.