Gua Sha is a traditional East Asian therapeutic technique in which a smooth-edged tool—often made of jade, horn, or ceramic—is used to scrape the skin firmly but gently, typically on the back, neck, or shoulders. The word combines 刮 (guā), meaning 'to scrape' or 'to rub', and 痧 (shā), an old term referring to a type of 'heat toxin' or stagnant pathogenic factor believed to cause symptoms like fever, headache, or fatigue in traditional Chinese medicine theory.

In practice, Gua Sha aims to promote circulation, release muscle tension, and stimulate the body’s natural healing response. It often leaves temporary, light red or purple petechiae (called 'sha') on the skin, which practitioners interpret as evidence of toxins being released. While widely used for colds, muscle pain, and stress relief, it is considered complementary rather than a substitute for modern medical treatment.