What are the possible reasons for hardening of stool and how to get rid of the same?

Lack of fluids etc: Multiple causes, lack of fluid intake is very frequent in summer, make sure keep enough fiber (fruits and whole grains), lack of activity and some medications are causes of constipation. Irritable bowel syndrome in some persons can express as constipation but this is a chronic condition and needs to be diagnosed after an evaluation by a physician.