What causes pain in the left side of neck?

Neck arthritis: There are several joints and intervertebral discs in the neck. These can wear out over time leading to pain. Degeneration of the joints or discs can cause neck pain, headaches, and shoulder pain. You can also get neck pain from a muscle strain. In some cases pain in the left side of the neck could be related to your heart so be sure to see you physician.

Anti-inflammatory: Neck pain usually comes from a degenerative joint or disc in the neck. Sometimes it's from a muscle strain or sprain. If pain lasts greater than 2 weeks or if you experience chest and/or arm pain see your physician.