Scoliosis is a medical condition in which the human or animal spine has a sideways curve. The curve is usually S-shaped or C-shaped. In some, the curve is stable. In others, though, it increases over time. Mild scoliosis does not often cause problems. Severe cases, however, can interfere with breathing and can cause pain.

The cause of most cases is unknown. However, it is believed to involve a combination of genetic and environmental factors. Risk factors include having affected family members.