Constipation is a problem with passing stool. Constipation generally means passing fewer than three stools a week or having a difficult time passing stool. Constipation is fairly common. A lack of dietary fiber, fluids and exercise can cause constipation. But other medical conditions or certain medicines may be the cause. Constipation is usually treated with changes in diet and exercise or with nonprescription medicines. Constipation may require medicines, changes in medicines or other treatments prescribed by a health care professional. Long-term constipation, also called chronic constipation, may require treating another disease or condition that can cause or worsen constipation.