Constipation can be classified into two main types- primary and secondary. Primary or functional or idiopathic constipation occurs without any clear cause. There are three different types of primary constipation that require constipation treatment medicine – normal transit, slow transit and outlet transit constipation. Secondary constipation occurs as a result of a health issue or due to the side effect of some medication. The most common causes of secondary constipation are diabetes, depression, hypothyroidism, irritable bowel syndrome (IBS) etc.