Hemorrhoids are common colon problems that affect both men and women equally. They can be internal (inside the anus) or external (under the skin around the anus), and occur when the veins around the anus or lower rectum become swollen and inflamed. Hemorrhoids are often caused by straining during a bowel movement. Other factors that may also lead to the condition include: pregnancy, anal intercourse, aging, and chronic constipation or diarrhea.