In most cases the onset of the scoliosis is gradual and painless. Scoliosis is usually noticeable on bending down. Sometimes a mild-to-moderate scoliosis can develop without being noticed by the child or his or her parents. This is often because the condition usually develops during adolescence when children often become more self-conscious. Parents and others are not likely to see a naked back (spine) and see the problem.

Scoliosis can cause mild pain and imbalance of the muscles. If scoliosis becomes more severe then it can become more disfiguring. This is because when the spine curves sideways, as the curve becomes more severe, the small bones (vertebrae) that make up the spine also twist round. This pulls any attached muscles, ligaments and ribs round with them. As a consequence:

If the scoliosis is in the chest (thoracic) region, the ribs and shoulder blade stick out like a bulge on one side of the back. Also, one shoulder may hang lower than the other and one shoulder blade may be higher than the other.

If the scoliosis is in the lower back (lumbar) region, it can make the pelvis thrust forward on one side and one leg may appear to be shorter than the other.
If scoliosis becomes severe and is not treated, it can cause problems later in life. For example, persistent back pain may develop and breathing problems or heart problems may develop if the deformity in the chest region is very severe. This is uncommon though.