What Is an Osmotic Laxative?

N. Madison
N. Madison

An osmotic laxative works to encourage a bowel movement by bringing more water into a person’s intestine, which has a softening effect on the stools. As a result, a person may have an easier time passing them. There are both prescription and over-the-counter (OTC) osmotic laxatives.

Polyethylene glycol, when mixed with water, offers laxative results.
Polyethylene glycol, when mixed with water, offers laxative results.

Polyethylene glycol (PEG) is an example of an OTC osmotic laxative. Widely known by the brand name Miralax®, this medication is sold as a powder that a person can mix with the beverage of his choice. Though the results are not immediate, this medication helps the intestine absorb water, resulting in softer bowel movements. Usually, the use of this medication results in a bowel movement within a couple of days. While it can cause side effects, some people report that they are mild in comparison to those experienced with other OTC laxatives.

Using laxatives on a regular basis may cause the intestinal tract and small bowel to become stagnant.
Using laxatives on a regular basis may cause the intestinal tract and small bowel to become stagnant.

Sometimes doctors prescribe prescription laxatives like lactulose for chronic cases of constipation. Also known by the brand names Cholac®, Generlac®, and Kristalose®, this medication is a type of man-made sugar that the body doesn’t digest. It is usually taken once a day in liquid form and travels to the intestine, pulling water into the intestine and producing a bowel movement within two days. Lactulose can cause minor side effects like other laxatives, but some patients develop severe vomiting or stomach pain while taking this osmotic laxative. In such a case, a doctor’s attention is usually warranted.

An osmotic laxative brings more water into a person's intestine.
An osmotic laxative brings more water into a person's intestine.

While this type of laxative often proves effective, it can also cause a range of side effects. Among the most common a person might suffer are bloating and cramping in the abdominal region and the passing of gas. Some people also experience diarrhea and become nauseated while taking these laxatives. Such symptoms are usually only temporary and fade after the medication has worn off. When a person uses laxatives too often or takes too much of one, however, dehydration can develop as well.

An osmotic laxative may cause abdominal cramping and bloating.
An osmotic laxative may cause abdominal cramping and bloating.

There are many brands of laxatives that work osmotically, and they are generally considered safe. Patients are typically advised to avoid taking an OTC osmotic laxative on a regular basis, however, as frequent use can cause the body to become dependent on it. With chronic constipation, a patient may need long-term treatment with a laxative but might consume more fiber, drink more water, and increase his physical exercise in an effort to help his body naturally.

An individual who has an eating disorder may abuse laxatives.
An individual who has an eating disorder may abuse laxatives.
Prescription laxatives are sometimes necessary for serious cases of constipation.
Prescription laxatives are sometimes necessary for serious cases of constipation.
The overuse of laxatives may lead to unintentional weight loss.
The overuse of laxatives may lead to unintentional weight loss.
People should avoid taking an osmotic laxative on a daily basis.
People should avoid taking an osmotic laxative on a daily basis.
N. Madison
N. Madison

Nicole’s thirst for knowledge inspired her to become a wiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

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Discussion Comments

SarahGen

My doctor put me on PEG several weeks ago. It's working but not as well as I thought it would. I thought that it would help me go once a day, everyday. It doesn't do that. Sometimes it makes me go every two days, sometimes it makes me go multiple times in a day. Sometimes I have diarrhea, sometimes I don't. I'm not too happy about it.

Is everyone else experiencing the same things?

stoneMason

@literally45-- They're very different. Osmotic laxatives trigger a bowel movement by hydrating the bowels. Stimulant laxatives trigger a bowel movement by triggering contractions.

I'm not a doctor but I think that osmotic laxatives are better because they're safer. They cause less side effects and don't cause dependency as much as stimulant laxatives.

Using stimulant laxatives regularly will lead to more constipation in their absence. The body will completely rely on them to have the contractions that lead to a bowel movement. This group of laxatives is not used often. Osmotic laxatives are usually the first choice of doctors.

literally45
Which type of laxative is better -- osmotic or stimulant?
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