Upper back pain, often experienced between the shoulder blades and the base of the neck, is a common complaint. This discomfort can range from a dull ache to a sharp, burning sensation. When this pain manifests primarily on one side, it suggests specific underlying causes that affect that particular area.
Common Musculoskeletal Causes
One of the most frequent reasons for one-sided upper back pain involves the muscles and ligaments in the area. Muscle strain can occur from sudden movements, lifting heavy objects incorrectly, or engaging in unaccustomed physical activity. For example, a sudden twist or an awkward reach primarily using one side of the body can overstretch or tear muscle fibers, leading to localized pain. This type of injury often results in soreness and tenderness when the affected muscles are touched or moved.
Poor posture contributes significantly to unilateral upper back pain, especially with prolonged sitting or standing. Slouching or consistently leaning to one side can place uneven stress on the muscles and ligaments supporting the spine. Over time, this imbalanced loading can cause certain muscles on one side to become overused and tight, while opposing muscles weaken, creating a painful imbalance. Activities like prolonged computer use with an uneven setup or carrying a heavy backpack consistently on one shoulder can exacerbate this.
Repetitive movements, common in various occupations or hobbies, can also lead to one-sided pain. Actions like consistently reaching, pulling, or twisting in a specific direction can repeatedly stress the same muscle groups and connective tissues. This constant strain can cause inflammation and micro-tears in the muscles or ligaments on the dominant side of the movement. A ligament sprain, which involves stretching or tearing the strong bands of tissue that connect bones, can result from sudden forces applied to one side of the upper back.
Nerve Involvement and Spinal Issues
Pain localized to one side of the upper back can originate from issues within the spine and the nerves that exit it. A pinched nerve occurs when a nerve root exiting the spinal cord becomes compressed or irritated. This compression might stem from a herniated or bulging disc, bone spurs, or inflammation, leading to pain that can radiate along the nerve’s pathway to one side of the back or even into the arm. The pain often presents as a sharp, shooting sensation, sometimes accompanied by numbness or tingling.
Herniated or bulging discs in the thoracic spine can cause significant one-sided pain. A disc might bulge or rupture to one side, impinging upon a nearby nerve root. This direct pressure on the nerve can produce localized pain on that side of the back, and it can also cause muscle weakness in the affected area. The specific location and intensity of the pain often depend on which nerve root is affected.
Facet joint dysfunction can also contribute to unilateral upper back pain. Facet joints are small joints located between the vertebrae that allow for spinal movement. If one of these joints becomes inflamed, arthritic, or misaligned, it can cause localized pain on the affected side of the spine. The pain worsens with movement or extension of the back and can refer pain to the surrounding muscles, creating a deep, aching sensation.
Referred Pain and Other Conditions
Sometimes, pain felt in one side of the upper back originates from a problem elsewhere in the body, a phenomenon known as referred pain. Internal organs can project pain to the back due to shared nerve pathways. For instance, issues with the lungs, such as pleurisy or pneumonia, can cause pain that is felt in the upper back, often on the side corresponding to the affected lung. Gallstones or other gallbladder problems might refer pain to the right upper back or shoulder blade.
Kidney issues, such as kidney stones or infections, can also manifest as pain in the lower part of the upper back, on the affected side. These conditions demonstrate how visceral problems can present as musculoskeletal pain. Therefore, a thorough medical evaluation is important to rule out these possibilities when other causes are not apparent.
Stress and anxiety can lead to significant muscle tension, particularly in the upper back and shoulders. Chronic stress can cause muscles to remain in a contracted state, leading to stiffness and pain. This tension can be asymmetrical, resulting in more pronounced discomfort on one side of the back.
When to Seek Medical Attention
While many instances of one-sided upper back pain resolve with rest and self-care, certain symptoms warrant immediate medical evaluation. It is advisable to consult a healthcare professional if the pain is severe, persistent, or does not improve within a few weeks of self-management. Pain that significantly interferes with daily activities or sleep also indicates a need for medical attention.
Certain “red flag” symptoms suggest a more serious underlying condition and require urgent medical assessment. These include pain accompanied by unexplained weight loss, fever, or chills, which could indicate an infection or systemic illness. The presence of new numbness, tingling, or weakness in the arms or legs, or changes in bowel or bladder function, suggests potential nerve compression or spinal cord involvement. Pain that is constant and worsens at night, or pain that is not relieved by rest, should also prompt a visit to a doctor.