Osmotics: Your poop softeners

Osmotic laxatives work by drawing water from the gut directly in to the stool. This happens through….ahem…osmosis. Water from inside of the gut gets attracted by the osmotic medication. Water then shifts into the stool this acts to soften the stool. Osmotics are essentially poop hydrators and they are the workhorses of pediatric constipation.

Osmotics play several important roles in children:

1. They soften stool so that any anal tears or hemorrhoids have a chance to heal up

2. As more water is drawn into the bowel, a light flushing effect helps move poop out more easily

3. They soften stool so children don’t have pain with pooping.

Osmotics do not directly ‘act on’ or ‘talk to’ the bowel in any way. They only shift water in to poop. That’s it! So, these are incredibly safe medications when used with guidance from your doctor.

But let’s take a deeper dive in to what worries families about these medications and address them in more detail. And just to state up front, these are real worries from rational people. It is essential for you to feel like you’ve made peace with osmotics up front, otherwise you won’t feel good using them. They are a “work horse” at The Tummy Handbook.

Let's address 5 Parent Concerns About Osmotics

1. Will my child become dependent on osmotics?”

The short answer is no. In order to develop a dependance or an addiction to a medication, there must be some interaction between the medication and neurologic receptors in the body. Since these medications do not “talk to” receptors, you cannot develop a dependence. 

An incredibly common observation from families is that these medications work, but as soon as they are stopped, their child reverts right back to where they started off of medication. This leads to the hypothesis that children are now ‘reliant on’ these medications. This is a false assumption. The correct reason why children revert back is that they never fully healed the problem to begin with. With a ‘whole body’ approach to managing constipation, the majority of patients will one day be able to stop medications.

2. Will osmotics cause dehydration?”

Since osmotics lead to shifts of fluid from the gut into the stool, water will be lost out of the body through the stool. That being said, these medications are so gentle that it would take a really large, sustained dose of medication (and lots of explosive, persistent diarrhea) before a child was at risk of getting dehydrated.

3. Will osmotics cause malabsorption or nutritional issues?”

Since there is a flushing effect through the bowels, food may move a little more rapidly through the bowels. However these medications are gentle enough that your nutrition will still be fully absorbed. It would take a really large, over dose of medication (and lots of explosive, persistent diarrhea) before a child was at risk of not absorbing their nutrition.

4. Will osmotics cause neurologic or psychiatric problems?”

The short answer is ‘no’, not as far as we can detect. Osmotics are widely viewed by Western medicine as safe and effective. However, it is a concern for many families. As outlined here in this widely cited New York Times article, there have always been concerns about tiny amounts of toxins being absorbed in to the blood stream from polyethylene glycol (PEG). There have been a series of studies over the past few years that have looked at safety of Miralax. One of the largest was published in 2018 and can be found here. It was rigorously designed and it aimed to determine whether blood toxin levels in children on Miralax rose upon ingestion. And while there was definitely an increase in blood levels of two of the breakdown products of Miralax, the rise was very very modest. It did not come close to reaching “toxic levels” by anyone’s standards. PEG is my most commonly recommended osmotic, specifically because of its excellent safety profile.  

5. Will osmotics cause my child discomfort?”

Yes and no. The medication itself doesn’t directly cause pain to the bowel. However, as it draws water into the colon, it will naturally stretch and contract as the stool moves. Stretch and contraction are perceived by the body as uncomfortable. So yes, getting poop out can be mildly uncomfortable. That being said, the degree of discomfort (if at all) is mild and will typically resolve once the colon is more empty. In other words, when really backed up, children may be uncomfortable until the medicines have started working well. 

How to use osmotics

Osmotics work best when used every day–not ‘occasionally’. Many parents will dose it “just when needed” because they don’t want to over-use them. While this is understandable, they work less well this way. It leads to lengthier amounts of time to feel better. It also leads to frequent swings in stool consistency (hard-soft-hard). This can be very frustrating for children. Keeping stool the same consistency every day is way more comfortable.

1. Treat like a dimmer switch

While there may be “official doses” for osmotic medications listed, these are just guidelines in my practice. In practice, you keep adjusting the dose of the medication like you would a dimmer switch on a light or a volume knob on your TV.

Essentially, you dial in the exact dose that makes all the poops are mushy. This is between Bristol 4 and 6 on the Bristol Stool Chart, if you are keeping score.

So, if you find that poops are still too hard, you should gradually increase the dose of the osmotic. If poops are too runny, you should gradually go down on the dose.

Of course, even though these are over the counter medications, you should verify all medication dosing with your doctor.

2. Don’t sweat the timing”

Osmotics do not “kick in” at certain time after taking it. If used every day, it will just keep all the poop soft. So don’t worry about timing too much. Just find one time every day that works for you.

A List of Osmotics

Not every product is right for every child. It is important to understand the pros and cons of each product. Here is a guide to the most common osmotics:

Polyethylene glycol 3350 (PEG):

Miralax® is the original brand name for PEG and is the product that most people are familiar with. PEG comes in a powder that is dissolved completely in water. It is clear, colorless, odorless, and tasteless (to most humans). It is a synthetic substance. The molecule is so big that it cannot get absorbed across the gut. PEG also happens to be my osmotic of choice for most children. It does require drinking a decent amount of fluid in order to be effective. For example, a standard adult dose is 8 ounces (240 ml) of water mixed with one capful of powder. Some younger children have a harder time drinking all of that fluid ON DEMAND. The problem with using PEG in younger children is that it requires drinking a decent amount of fluid on demand. Try getting a 2 year old to drink down 4 ounces of fluid on demand every single morning. That’s a big ask of a little guy. I often will use a magnesium product or lactulose (see below) for those challenged trying to drink so much fluid.

Magnesium:

There are multiple forms of magnesium (Magnesium citrate, milk of magnesia to name two) and they all work the same. Typically magnesium requires a much smaller volume—typically on the order of teaspoons to tablespoons (instead of ounces needed with PEG). Most products have a taste to them, and often that taste is a little hard to handle. It is often a “cherry” or “strawberry” flavor but children tend to be “mixed” about whether they want to take it or not. It can be mixed with food or liquid as you wish.

Lactulose:

This is a sugar that doesn’t get absorbed into the bloodstream. The sugar sits in the gut and draws water into the stool to soften it. Lactulose is probably the most gentle of the laxatives that I use. I mostly use this in infants under age 6 months. It tends to be “weak” for children over age 1 but it definitely can work in all age groups. You only need a small volume to see an effect, so it works particularly well in infants and young toddlers. The sugar doesn’t actually get absorbed into the blood stream so there are not sugar highs!

Juice:

Prune juice, apple juice, grape juice are all osmotic laxatives, believe it or not! The sugars in the fruit draw water into stool. It’s certainly very “natural” to use juice. I prefer lactulose to juice, however, because juice will spike your child’s blood sugar, whereas lactulose will not.

Fiber:

Yes! Believe it or not, good old fashioned dietary fiber is an osmotic. It does draw water into stool. Fiber is my substance of choice to keep a regular child regular. In other words, when the question is: %22How do I avoid constipation?%22 the answer is often FIBER. Just eat a diet high in fiber and water, and you will most likely do just fine. The problem becomes using fiber to TREAT constipation. Often, the bowels are loaded up with stool and gas. Fiber often exacerbates the discomfort associated with constipation. You also need LOTS of fiber in order to get the effect you are looking for. It’s not as efficient as PEG or magnesium in softening stool and beginning the healing process.