Constipation is the main cause of hemorrhoids. This causes bowel movements to put strain on the rectal area, thereby putting pressure on the blood vessels and causing swelling and irritation. Strained bowel movements can cause bleeding from the blood vessels in the rectal area as well. Preventing constipation is an important step in preventing and minimizing the effects of hemorrhoids.

Irritable Bowel Syndrome, known as IBS, can cause hemorrhoids, especially in cases when IBS is dominated by constipation. Diarrhea is also known to put extra pressure on the rectal blood vessels. Portal Hypertension, which is an increase in the pressure of the blood vessels running from the intestines to the liver, can cause hemorrhoids due to the increased blood flow and pressure.