How does stress affect the body?

Doctors and researchers have established a strong link between the stress a person feels in their mind and its effects on their body, including the stomach and intestines. The body is naturally “wired” to respond to stress.

When you feel anxious, your brain sends signals to your body via the sympathetic nervous system. This is known as the fight-or-flight response. Your heart speeds up, you feel more alert, and your muscles tense up, ready for action.

However, this response is biologically intended to help a person flee from someone or something chasing them — not for the everyday stressors of jobs, deadlines, family commitments, money, and more.

If your stress is leading to gastrointestinal upset, including diarrhea, there are steps you can take to feel better.

Doctors have been performing research on how stress can cause diarrhea for decades. One of the most famous studies was performed by Almy and Tulin in the late 1940s. The doctors used special instruments to measure how much the colon contracted during stressful situations, such as in traffic and when performing mentally challenging tasks.

In what wouldn’t be ethical today, the doctors even told study participants they had colon cancer to measure their intestinal response (later telling them they didn’t).

What they found was what many people with stress know: Stressful situations can lead to intestinal cramping. And this can lead to diarrhea.

Fortunately, advances in research and technology have meant doctors can pinpoint with greater accuracy how the brain affects the intestines.

Researchers have found the stomach and intestines actually have what can be considered their own nervous system. Doctors call this the enteric nervous system. This nervous system responds to the stress hormones the body releases.

Stress triggers the release of hormones that signal the enteric system to slow motility, or movement, in the stomach and small intestines. Doctors call these hormones corticotropin-releasing factors (CRF).

However, these same hormones trigger more movement in the large intestine. This could be the body’s response to try and remove potentially harmful toxins in the body. But it also has the effect of making you have to go to the bathroom and could lead to diarrhea.

People can experience the physical effects of stress in different ways. Some always experience an upset stomach or abdominal cramping. Others have different symptoms. Examples of these can include:

Chronic stress can cause long-term and serious health problems, such as:

Stress and bowel conditions

Stress can especially have an impact on people with irritable bowel syndrome (IBS). Researchers have found that people with IBS have colons that are more susceptible to stress. Their intestines seem to react more quickly and in greater response to stress than a person who doesn’t have IBS.

Research estimates that 50 to 90 percent of people who receive treatment for IBS also have anxiety or depression. People with IBS can often benefit from taking medication to reduce stress and anxiety.

Stress can also have a profound effect on people with inflammatory bowel disorders (IBDs) such as Crohn’s disease and ulcerative colitis. Because these conditions can damage the intestines, it’s important to avoid flare-ups whenever possible.

Most treatments for stress-related diarrhea involve identifying and addressing underlying stressors:

  • Avoid foods that can further contribute to diarrhea and digestive irritability. Examples include dairy products, carbonated drinks, and caffeinated beverages.
  • Recognize sources and signs of stress. If you experience an episode of diarrhea, reflect on what you were doing before the episode that triggered stress.
  • Set your goals. Define what’s important in your life. Assess if there are pursuits you’re putting time toward that aren’t as important. By eliminating these things, you can likely increase your relaxation time and reduce stress.
  • Use any free time to engage in a relaxing activity. Examples include meditation, tai chi, journaling, yoga, listening to music, or reading.

A person may temporarily consider taking antispasmodic medications to reduce the likelihood diarrhea will occur. These medications treat muscle spasms. However, they won’t address the underlying stress that’s causing the diarrhea in the first place.

In addition to these treatments, many people can benefit from counseling to help them identify new ways to better manage stress. Sometimes seeing a professional can help a person identify patterns of stress in their life. A doctor can also recommend techniques on how to better respond to stress and anxiety.

Stress can be overwhelming. It’s important to ask for support if you need it. See your doctor if:

  • You’re using substances, such as alcohol or drugs, to cope with your stress.
  • You’re having thoughts of self-harm.
  • Your episodes of stress-related diarrhea feel more like the norm than the exception.
  • The at-home treatments you’re trying aren’t working.

If something feels out of the ordinary or is affecting your daily life, talk to your doctor. Solutions are available, and they can prevent this problem.