Chronic pain is pain that doesn't go away. Unlike acute pain, which comes on suddenly and can usually be traced directly to a cause, chronic pain lingers—and it's rarely easy to tell what's causing it.

That's the situation that millions of chronic pain sufferers are in: they have pain, but there's no easy cause to point to.

In fact, chronic pain in itself can be considered a disease or condition. Most times, pain is a symptom of another condition or problem; it's often considered a warning sign that something is wrong. If pain becomes chronic, though, it's no longer a warning sign of a problem—it is the problem.

One typically accepted definition of chronic pain is pain that's still present, even after the related injury or disease has been healed. It is pain that persists 6 months or more after the related injury or disease has been dealt with.

Another definition is pain that's present, even if there isn't a clear injury or disease causing it.

Chronic pain is hard to define precisely because it takes on so many forms. You'll learn about the types of chronic pain in this article. Determining the type of pain is a big step towards finding a treatment that helps you deal with your chronic pain.