Back pain may be caused by mechanical or structural changes in the spine, inflammatory conditions, or other medical conditions.

A common cause of back pain is injury to a muscle or ligament. These strains and sprains can occur for many reasons, including improper lifting, poor posture and lack of regular exercise. Being overweight may increase the risk of back strains and sprains.

Back pain also may be caused by more-serious injuries, such as a spinal fracture or ruptured disk. Back pain also can result from arthritis and other age-related changes in the spine. Certain infections can cause back pain.

Possible causes of back pain include:

Mechanical or structural problems

1. Herniated disk
2. Muscle strains (An injury to a muscle or to tissue that connects muscles to bones, called a tendon.)
3. Osteoarthritis
4. Scoliosis
5. Spinal fractures
6. Spondylolisthesis (when spinal bones slip out of place)
7. Sprains (and strains)

Inflammatory conditions

1. Ankylosing spondylitis
2. Sacroiliitis

Other medical conditions

1. Endometriosis — when tissue that's similar to the tissue that lines the uterus grows outside the uterus.
2. Fibromyalgia
3. Kidney infection (also called pyelonephritis)
4. Kidney stones (Hard buildups of minerals and salt that form inside the kidneys.)
5. Obesity
6. Osteomyelitis
7. Osteoporosis
8. Poor posture
9. Pregnancy
10. Sciatica (Pain that travels along the path of a nerve that runs from the lower back down to each leg.)
11. Spinal cord tumor