Neck pain on the left side usually results from a benign cause, like muscle strain from sleeping in an awkward position. Sometimes, a more serious cause may be a tumor or rheumatoid arthritis.

many conditions that are not specific to your left-hand side (like ovarian cyst ruptures) can be felt on that half of your body. Pain in your left side does not mean you have any of the following ...

or bowel or bladder dysfunction, go to the emergency room," Chiodo says. 9. Tumor While rare, spinal cancer or a spinal tumor can cause back pain on the left or right side of the back. Other ...