Hemorrhoids, also called piles, are swollen, inflamed veins inside the anus or under the skin around the anus. These are very common in both men and women. The American College of Gastroenterology estimates that about half of all individuals have hemorrhoids by age 50. Hemorrhoids also are common in pregnant women.

Hemorrhoids usually are not dangerous or life-threatening. They can develop from any increase in pressure in the veins in the lower rectum. Common sources of pressure include:

  • Constipation and straining
  • Diarrhea
  • Sitting (especially on the toilet) or standing for a long time (such as at a job)
  • Obesity
  • Diet, especially those high in red meats and low in fiber
  • Pregnancy and childbirth

Hereditary factors also may be involved in the risk for developing hemorrhoids, such as in people predisposed to having weakened blood vessels. During pregnancy, hemorrhoids can develop due to the pressure of the fetus in the abdomen, as well as hormonal changes, which cause hemorrhoidal vessels to enlarge. The process of childbirth also puts severe stress on these vessels.