Laxative are used to treat constipation when change of lifestyle and diet are not effective. There are several types of laxatives which induce bowel movements or loosen the stool and are used according to age, medical condition, functional status and some other factors such as pregnancy. Laxatives provide relatively fast constipation relief but like other medications which are available over-the-counter they can cause several more or less sever side effects and can also lead to dependency.
The least harmful and most often recommended laxative are bulk-agents such as psyllium husk, methylcellulose and flaxseed which make the stool bulkier and easier to expel. They work slower than other types of laxatives but they interfere with normal colon function in lesser extent than the other laxatives. Bulk-agents should be taken with plenty of water.
Lubricants such as mineral oil loosen the stool and make it easier to expel but might decrease absorption of some fat-soluble vitamins and minerals.
Osmotics such as sodium phosphate, magnesium sulphate, sorbitol and lactulose increase water in the intestines and soften the stool. Some osmotics are not appropriate for long term use. They might cause flatulence and cramps
Stimulants such as senna (Ex-lax) and bisacodyl tablets (Ducolax, Corroectol) cause contractions in the intestines and are appropriate only for the most severe cases of constipation. Use of stimulants in long term can cause dehydration, alter electrolyte balance, cause lazy bowel syndrome and dependency. Stimulants should be used only occasionally when other treatments are not effective.