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

• Herniated disk
• Muscle strains (An injury to a muscle or to tissue that connects muscles to bones, called a tendon.)
• Osteoarthritis (the most common type of arthritis)
• Scoliosis
• Spinal fractures
• Spondylolisthesis (when spinal bones slip out of place)
• Sprains (Stretching or tearing of a tissue band called a ligament, which connects two bones together in a joint.)

Inflammatory conditions

• Ankylosing spondylitis
• Sacroiliitis

Other medical conditions

• Endometriosis — when tissue that's similar to the tissue that lines the uterus grows outside the uterus.
• Fibromyalgia
• Kidney infection (also called pyelonephritis)
• Kidney stones (Hard buildups of minerals and salt that form inside the kidneys.)
• Obesity
• Osteomyelitis (an infection in a bone)
• Osteoporosis
• Poor posture
• Pregnancy
• Sciatica (Pain that travels along the path of a nerve that runs from the lower back down to each leg.)
• Spinal cord tumor

Most back pain gets better within a few weeks without treatment. Bed rest isn't recommended. Pain medicines available without a prescription often help reduce back pain. So might applying cold or heat to the painful area.

Seek emergency medical care

Call 911 or emergency medical help or have someone drive you to the emergency room if your back pain:

• Occurs after trauma, such as a car crash, bad fall or sports injury.
• Causes new bowel or bladder control problems.
• Occurs with a fever.

Schedule a doctor's visit

Call your healthcare professional if your back pain hasn't improved after a week of home treatment or if your back pain:

• Is constant or intense, especially at night or when lying down.
• Spreads down one or both legs, especially if it extends below the knee.
• Causes weakness, numbness or tingling in one or both legs.
• Occurs with unintended weight loss.
• Occurs with swelling or change in skin color on the back.