Pain and IBD

The perception of pain occurs in your central nervous system (CNS). The CNS consists of your brain and spinal cord. Your CNS perceives pain as a result of signals sent to it from the ‘injured’ area.  

The severity of the pain you experience is a combination of signals from the affected area and what you think the pain means for you (perception). The meaning of pain is influenced by how well you think you can manage the pain, your emotional reaction to the pain, and even cultural factors. The social setting where you live, your family’s reaction to your pain, and your past experiences can also influence how you feel pain. 

There are many nerves in your gastrointestinal (GI) tract, and some of them can contribute to the sensation of pain. Individual nerve cells, called neurons, send pain signals to the spinal cord. The spinal cord then sends the signals to the brain.

But first, there needs to be something that stimulates your neurons to send these signals. During a flare of inflammation in IBD, certain chemicals, called inflammatory mediators, are released. These cause tissue damage. They also stimulate pain signals to be sent.

Inflammation and the release of inflammatory mediators also act on the neurons in your gut. They change sensitivities to pain so that what would normally not be painful becomes very painful. This process is called peripheral sensitization (as opposed to central sensitization, which is where changes are made in the neurons in your spinal cord). Peripheral sensitization can cause normal sensations of your bowels to become painful.

Despite being in endoscopic or clinical remission (no evidence of active disease), you may continue to experience pain. This is sometimes due to changes in your nervous system. When there is inflammation and pain, your pain-sensing neurons and spinal cord neurons may go through long-term changes. The hyperactivity in these pain pathways can continue even when the initial inflammation has gone away.

Other types of non-inflammatory pain can arise in people with IBD. These include abdominal wall pain (which can sometimes arise after surgery), pelvic pain, and arthralgias (non-inflammatory joint pain). 

Depression and anxiety can lead to changes in the walls of your GI tract. The cells in the lining of your GI tract control what gets into the inside of your intestines. This process is called gut barrier function. Anxiety and depression can cause these cells to function poorly. This can expose the wall of the gut to bacteria. The bacteria, in turn, trigger mild inflammation, leading to pain.

Your ability to cope with pain can affect your perception of pain. If you have a lot of anxiety or sensitivity about your IBD, it can make your pain worse. 

Find out more about anxiety and depression in our section on Psychological Risk Factors for Pain.

Stress is known to change the microbiota (bacteria, fungi, and viruses in your gut), and this can lead to pain. Stress can affect motility, which is the movement of food through your intestine. It can also affect pain pathways in ways that might persist after the inflammation is gone. Stress tends to increase the risk of illness in patients who have a low level of activity.