What Are Osmotic Laxatives and How Do They Work?

a small glass of water

Even when you exercise, drink plenty of water, and eat high-fiber foods, you can sometimes feel blocked  and may experience occasional constipation.  The use of an osmotic laxative like MiraLAX can help relieve occasional constipation.

What are osmotic laxatives?

You may notice that the word “osmotic” is pretty close to “osmosis,” which means we’re talking about the movement of water.  Osmotic laxatives, such as MiraLAX, attract water and keeps it  in your colon.  This action allows Miralax to hydrate and soften stools and unblocks your system without causing harsh gastrointestinal side effects.

What do they do?

Basically, osmotic agents, such as polyethylene glycol found in Miralax, work with the water in the colon to unblock a person’s system naturally.  Soluble, non-absorbable PEG 3350 hydrates, softens and eases stools by gently attracting water in the colon through a process known as osmosis. The water increases stool volume and stretches the wall of the bowel triggering the defecation reflex, so the digestive system can be unblocked naturally. 

How Do I Take Them?

It all depends on what kind of osmotic laxative you have. Some of the products that fall under this category are pre-mixed liquids, some are tablets you chew up and swallow, and some are powders, e.g. MiraLAX, which you mix into 4-8oz of a liquid before drinking. MiraLAX can be mixed into any beverage, hot or cold. Some examples include coffee, tea, water, orange juice, iced coffee, ice water, coconut water, smoothie, iced tea, and seltzer. 

How Will I Feel?

Osmotic laxatives, such as MiraLAX,  are generally well tolerated and have very few side effects. Studies have shown that MiraLAX increases bowel movement frequency with less straining and improves stool consistency. In case gastrointestinal side effects occur they are usually mild and transient.


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