Constipation is a common but painful condition that occurs when bowel movements become infrequent or difficult. It can be caused by nutritional deficiencies, stress, pregnancy, cancer, depression, and more. The best way to prevent constipation is eating a healthy diet, exercising, and drinking plenty of water. Laxatives can help relieve constipation. Follow the links below to find WebMD's comprehensive coverage about what causes constipation, how to treat it, and more.