Can anxiety and stress change stool shapes, colour and ability to pass a stool?

Stress/Bowel Pattern. Stress does not necessarily change stool color, but can affect bowel movement patterns. Some patients can have what is known as irritable bowel syndrome in which stools can vary from constipation to diarrhea. This condition is often diagnosed after all other organic/pathologic conditions are excluded. Wise to see your doctor.
See MD. No direct connection between stress and changes in stool. Suggest you see your primary care provider to find out what can be causing bowel changes. Not knowing for sure may be contributing to your anxiety and stress. If your anxiety persists, it may be helpful to speak to a psychotherapist for coping strategies and guidance. Hope this helps.