Back pain is a common complaint amongst adults. For individuals in their 20s and 30s, back pain can often be attributed to general daily life issues, such as sitting at a desk too long or overdoing it while exercising. For those in their 40s and older, the start of degenerative diseases and age-related injuries are typically more to blame.

Back pain may also be isolated to one side of the body. If the cause of back pain can be pinned down to a specific activity, it is usually nothing to worry about. If, however, pain appears gradually, appears suddenly with no explanation or persists, you may have a more serious condition that needs medical attention.

Below are potential causes of back pain on one side:

Tissue Injuries

Back pain on one side is most commonly the result of injury to the spinal structure, occurring in the muscles, ligaments, joint or discs. Back muscles run up and down the left and right side of the spine, without crossing the midline. It would therefore make sense that muscle back pain is only on one side of the body.

Muscle strains are the most frequent cause of lower back pain on one side of the body. This includes lower right back pain and lower left back pain. Pain experienced in the upper back, including upper left and upper right back, is usually the result of joint dysfunction or muscular irritation. The large upper back muscles attached to the shoulder blades and back of the rib cage are especially at risk of tightness and strain. Individuals who have pain from joint dysfunction are likely to have either had a sudden injury, or be experiencing natural degeneration from aging. Muscular irritation is more commonly due to overuse of the back muscles, a lack of strength or poor posture.

Degenerative Conditions

Age-related degenerative diseases may cause back pain, including back pain on one side of the body. These include wear and tear of the joints from arthritis, bone spurs – where worn-away cartilage triggers the incorrect compensational growth of new bone – or a narrowing of the spinal column known as spinal stenosis. Symptoms may include lower left or lower right back pain, as well as upper left or upper right back pain. Pain may also cause weakness or radiate down the leg.

Internal Organ Issues

While it may not be the first thought when looking for the source of injury, back pain on one side of the body may be the result of issues with various internal organs. In these instances, back pain may be felt a little deeper in the body, and will typically present with other symptoms.

The kidneys are positioned towards the lower back and therefore may cause lower right or lower left back pain if infected. Pain from kidney stones infection typically radiates down from the flank towards the groin, and exists alongside other symptoms, such as painful urination or nausea. Issues with the gallbladder or biliary tree may cause pain in the middle back, with some individuals reporting back pain on one side, particularly the right.

Appendicitis may occur when a blockage or infection disturbs the appendix, resulting in inflammation. This often presents as an intense pain in the right side of the abdomen that can travel to create lower right back pain.

Back pain may also be the result of ulcerative colitis: chronic inflammation of the large intestine that is likely to also generate digestive issues, abdominal cramping and fatigue.

In women, pelvic pain caused by endometriosis, fibroids or both cancerous and benign ovarian tumors can radiate, causing lower right or lower left back pain. This pain will present with other issues, such as pelvic pain, abnormal menstruation and frequent urination. Lower back pain to one side, along with accompanying symptoms, may also be caused by pelvic inflammatory disease, an infection typically occurring when sexually transmitted diseases spread to the ovaries, uterus or fallopian tubes. If you’re experiencing back pain on one side of the body that does not improve with rest or medication, it’s better to treat it with caution. Consult with a doctor if pain is affecting your day-to-day life.