What Are Laxatives? How Do Laxatives Work?

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Main Category: GastroIntestinal / Gastroenterology
Also Included In: Irritable-Bowel Syndrome
Article Date: 20 May 2009 - 15:00 PDT

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The English word "laxative" comes from Old French laxative, which came from the Latin laxatus. The Latin word Laxare means "to loosen", while the Latin word Laxus means "loose, lax". Reference books indicate that the noun meaning "a laxative medicine" in the English language emerged around 1386 A.D. According to Medilexicon's medical dictionary, a laxative is "A mild cathartic; a remedy that moves the bowels slightly without pain or violent action". A cathartic is an agent which has a purgative action (empties you out).

For constipation

A laxative (or purgative) is a food, compound, or medication which when consumed either induces bowel movements, or loosens the stool. Laxatives are generally taken when a person has constipation.

Before bowel surgery or a bowel examination

Some stimulant, lubricant, and saline laxatives, as well as enemas are also used before bowel examinations. The UK authorities had to issue new guidelines for the use of laxatives prior to bowel surgery or examination.

For hemorrhoids

A study carried out by Spanish researchers found that laxatives in the form of fiber improve symptoms of hemorrhoids, especially bleeding.

Eating disorders and laxative abuse

Laxative abuse can be found among people with anorexia nervosa, an eating disorder.

Laxatives accelerate the elimination of undigested food in the large intestine and colon. Too many laxatives will often result in diarrhea.

Types of laxatives

• Foods (mainly plant-based foods)
  
  The following foods may act as laxatives. They are more effective at preventing constipation than treating it:
  
  Almonds, Aloe Vera, Apples/Apple Juice, Artichokes, Bananas, Basil, Beets, Blueberry, Carob, Chicory, Chios Mastic(gum), Cranberry, Coconut, Coffee, Cornmeal, Dandelion, Dates, Dried apricots, Endive, Fenugreek, Figs, Flaxseed, Grapes, Kale, Liquorice, Mangos, Molasses, Oranges, Papayas, Parsley, Peaches/Apricots, Pears, Persimmons, Pineapple, Plums, Prunes/Prune Juice, Rhubarb, Rutabagas, Soybeans, Strawberry, Tamarind, Tangerine, Tea, Tomato, Tomato Juice, Vanilla, Walnuts, Watercress, Winter Squash, Yams, Olive oil.



• Bulk-producing agents
  
  These work on the small and large intestine and generally take from 12 to 72 hours to work. They are also known as bulk-forming agents, bulking agents, and roughage. They make the stool become bulkier and retain more water.
  
  Examples are: Metamucil (psyllium husk), Citrucel (methylcellulose), dietary fiber, broccoli, apples, and polycarbophil.



• Stool-softeners (surfactants)
  
  These work in the small and large intestine and generally take from 12 to 72 hours to work. They cause fats and water to penetrate the stool, making it easier to move down the digestive system. After prolonged use they become much less effective. They are effective for people with occasional constipation.
  
  Examples are: Colace, Diocto (docusate)



• Lubricants (emollients)
  
  These work in the colon and take from 6 to 8 hours to work. They make the stool slippery so that it moves down the intestine more easily and faster.
  
  Example: mineral oil



• Hydrating agents (osmotics)
  
  These make the intestines hydrate (concentrate more water within), thus softening the stool. There are two types:


• 1. Saline laxatives
  
  These work on the small and large intestine and take from 30 minutes to 6 hours to work. They attract and retain water in the hollow of the intestine, the tube of the intestine (intestinal lumen), thus softening the stool. They also increase intraluminal pressure.
  
  Examples: Dibasic sodium phosphate, milk of magnesia (magnesium hydroxide), Epsom salt (magnesium sulfate), monobasic sodium phosphate, sodium biphosphate, magnesium citrate.



• 2. Hyperosmotic agents
  
  These work in the colon and take from 30 minutes to 3 hours to work. Glycerin suppositories and Lactulose are examples. The glycerin suppositories work mostly by encouraging bowel movements by drawing water into the bowel from surrounding body tissues (hyperosmotic action).
  
  Examples: Glycerin suppositories, Sobrbitol, Lactulose, PEG (polyethylene glycol)


• Stimulants (irritants)
  
  These work in the colon. These work by stimulating the wave of contractions that pass along the colon propelling the stools along. Under certain circumstances they can be dangerous. Castor oil is sometimes more effective in achieving complete evacuation.
  
  Example: Cascara, pholphthalein, Dulcolax (bisacodyl), Senna, Aloin (from Aloe Vera), castor oil, bisacodyl suppository, Microlax.



• Castor oil
  
  This works in the small intestine. It works directly on the mucosa in the intestines and alters water and electrolyte secretion.



• Relistor (methylnaltrexone bromide)
  
  Relistor is commonly used to treat patients with opioid-induced constipation (OIC). It is especially useful for patients with advanced illness who are receiving palliative care, when response to laxative therapy has not been sufficient.

Unexpected side-effect of some chewing gums

Some chewing gum sweeteners have a laxative effect. A study published in the British Medical Journal found that many sugar-free chewing gums have sorbitol, a sweetener. Sorbitol is a laxative which is poorly absorbed by the small intestine. Too much sorbitol intake can lead to significant weight loss. The warning came after doctors treated two patients who had chronic diarrhea, abdominal pain and dangerously excessive weight loss.

Written by Christian Nordqvist

Original article date: 04 July 2004
Article updated: 20 May 2009

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