(Adam Gault/Getty Images)

By Dr. Justin Larkin, ABC News Medical Unit

More than 25 percent of people in the U.S. experience chronic pain, whether it's from a bad back, cancer surgery or a condition such as fibromyalgia.

Related: A Close Up Look At Acupuncture For Pain

The concept of chronic pain is hard to define and highly subjective. That's why experts say it's so hard to treat. The most common explanation is that any pain lasting longer than three months after a normal healing process can be classified as chronic.

With chronic pain affecting so many Americans, we made it the topic of this week's medical tweet chat moderated by ABC News chief health and medical correspondent, Dr. Richard Besser. Patients and practitioners shared their thoughts on this important medical issue.

In case you missed it, here's the full transcript. Or, scroll through the top twelve tweets below. If you've got something to add, leave it in the comments section below.

T1: #Chronicpain is considered pain that lasts longer than 12 weeks #abcdrbchat

- NewYork-Presbyterian (@nyphospital) April 22, 2014

T6: Neuropathic pain affects 8% of world population - a challenging unmet medical need. #abcdrbchat pic.twitter.com/8gJLGLDGlp

- Neuropathy Associati (@NeuropathyAssoc) April 22, 2014

@abcdrbchat T4 Fibromyalgia affects up to 4% of the population… widespread body pain, fatigue, sleep disturbance… #abcdrbchat

- Dr. Paul Christo (@DrPaulChristo) April 22, 2014

T6: Neuropathic pain originates in nerve tissue. Often described as "tingling" or "burning". #abcdrbchat

- Robert Sawicki (@DrSawicki) April 22, 2014

T8 Misuse is a huge problem. We need regulations to ensure that these drugs only get into the hand of people who need them #abcDrBchat

- Kristen Santiago (@Kristen_CChange) April 22, 2014

T9. One stigma is chronic pain patients using handicapped parking spots and getting dirty looks. We hear that a lot. #abcDrBchat

- CreakyJoints.org (@CreakyJoints) April 22, 2014

T10 More research into the transition from acute to chronic pain is needed #abcdrbchat

- UPMC/PittHealth News (@UPMCnews) April 22, 2014

T10: We need a more objective assessment of pain, therapies that don't lead to abuse or addiction #abcdrbchat

- NewYork-Presbyterian (@nyphospital) April 22, 2014

T2: A whole person approach is important in pain management. How much of pain is physical? #HPM #abcDrBchat

- Cory Ingram (@cjingram) April 22, 2014