Like a fever, constipation can be caused by many different conditions. These may include a sudden change in your diet or level of activity, dehydration, stress, or side effects of a new medication. In some instances, constipation is due to a problem with the bowel itself, such as irritable bowel syndrome, diverticulitis, hemorrhoids and other anal disorders, or even cancer. Occasionally, health problems such as an underactive thyroid, kidney disease, long-standing diabetes, high blood calcium, or low blood potassium can slow things down. Pregnancy is another common cause of constipation.
Many drugs have a side-effect of constipation.
Of course, there are many others. Constipation not responding to simple measures or symptoms that persist over six weeks signal a need for medical evaluation. Other symptoms such as weight loss, rectal bleeding, abdominal pain, or the discovery of anemia also require a full investigation. Your doctor can help you sort out the many possible causes and plan a course of treatment. In addition to obtaining a medical history and performing a physical exam, he may request some blood tests, and a special scope evaluation of the colon.