Miralax v. Ex-Lax for Childhood Constipation

By Steve Hodges, M.D.

For a child in treatment for encopresis (chronic poop accidents), which is more useful as an adjunct to the Modified O'Regan Protocol: Ex-Lax or Miralax? Is it a good idea to reward a constipated 4-year-old for pooping on the toilet? How often should a child with enuresis be x-rayed for constipation?

Those are a few of the questions posted this week in our private support group for treating enuresis and encopresis. Here's my take.

Q: Is there a benefit to Ex-Lax vs. a laxative like Miralax or magnesium? My 10-year-old has never had a dry night and has been on M.O.P. for two months. I always figured he would outgrow bedwetting, but I finally realized that wasn’t happening. Currently, he’s doing a nighttime enema plus either magnesium citrate or one Ex-Lax square at night.

A: Stimulant laxatives like Ex-Lax and osmotic laxatives like PEG 3350 and magnesium serve different purposes, so I wouldn't say one is "better" than the other. Ex-Lax is for triggering a bowel movement, whereas osmotic laxatives are for softening stool.

Keeping stool mushy makes pooping easier and less painful, which, in turn, often helps kids poop. However, that's not the same as directly triggering a bowel movement, the way senna-based laxatives such as Ex-Lax do.

With Ex-Lax, it’s important for the child to take a strong enough dose to trigger a poop within 5 to 8 hours . As explained in the M.O.P. Anthology, I don’t recommend taking Ex-Lax at night, since the urge to poop will strike while the child is sleeping, defeating the purpose of the laxative.

Finding the right Ex-Lax dose takes some experimentation. Most 10-year-olds need significantly more than 1 chocolate square (or the equivalent dose in pill form) to trigger a bowel movement. I recommend families experiment with Ex-Lax dosing and timing on weekends, so the urge doesn't strike during math class or soccer practice.

Section 5 of the Anthology 5th Edition explains when to use a daily enema + Ex-Lax (the M.O.P.x regimen) and when to use a daily enema + an osmotic (the Standard M.O.P. regimen). I suggest reviewing the section and deciding which scenario protocol suits your son best.

READ: Doctors Get Encopresis Treatment All Wrong

Q: My 4-year-old has encopresis, and our biggest struggle is our reward system. He asks, "What do I get if I poop?" Today he pooped 6 times (all small pellets) in 2 hours just to get more toys.  My 5-year-old is frustrated because he doesn’t get as many stars for his chore chart and feels it’s unfair his brother gets more rewards for potty training. Any advice on how to outsmart my 4-year-old with a reward system that works?

A: I’d drop the reward system entirely. Rewards send the message that the child is in control of his bowels, but your son doesn't have control, despite what it may seem.

In kids with encopresis, the pile-up of stool stretches the rectum, compromising its tone and sensation. These kids can’t feel the urge to poop, at least not entirely or consistently, and when they do poop, they don’t have the oomph to fully evacuate. So, even more stool piles up. The rectum is so floppy that some poop drops out of the child’s bottom, without the child noticing.

I wouldn’t insist your son sit on the toilet and try to poop — it’s just not useful at this stage and is likely to trigger a power struggle. Once his rectum is clears out, retracts to normal size, and regains sensation, these difficulties will disappear. For now, I’d just focus on your son’s constipation treatment and praise him for complying with the regimen.

READ: “Potty Regression,” “Potty Refusal,” “Not Fully Potty Trained": Why These Terms Should be Canceled

Q: I have a friend in the UK whose son is struggling with constipation and soiling. Sometimes he poops 4-5 times a day, and then he’ll go a week without pooping and have explosive accidents. Doctors tell my friend that her son is fine because he poops most days and any issues are “behavioural.” She’d like an x-ray before deciding whether to go against doctor’s recommendations and treat her son with M.O.P. However, her doctor won’t order an x-ray. Any suggestions?

A: An x-ray isn't necessary for a child with encopresis, since it won't reveal anything that isn’t already evident from the child’s symptoms. What you describe is a clear-cut case of chronic constipation. Plenty of severely constipated children poop daily, and pooping multiple times a day is a red flag, too, indicating the child is not completely evacuating. And certainly, any child who goes a week without pooping has a big pile-up of stool in the rectum. Encopresis is not a behavioral condition. The child is soiling because his rectum is clogged and stretched.

READ: Yes, Your Child Can Poop Every Day and Still Be Constipated

X-rays are particularly hard to come by in the U.K., and I don’t recommend pushing for one in a situation such as this. I reserve x-rays for enuresis patients — to rule out the rare causes of wetting in the absence of constipation (such as posterior urethral valves or tethered cord syndrome) or to assess a child’s rectum when enuresis persists despite aggressive constipation treatment. For example, an x-ray can distinguish between a rectum that’s still clogged and a rectum that is empty but still enlarged, scenarios that would warrant different treatment approaches. But with encopresis, there's really nothing to be gained from an x-ray.

Perhaps if you explain all this to your friend, she will feel confident enough to start treating her son for constipation. An aggressive regimen such as M.O.P. is likely to halt poop accidents quickly and doesn’t require prescription medication or particular medical expertise.

READ: How to Disagree with Your Doctor About Bedwetting Treatment

Q: How often should we be getting x-rays? My 7-year-old is on day 70 of Multi-M.O.P. After two weeks of treatment, her encopresis stopped, but her bedwetting continues. I’m trying to be patient because I know it takes a while for bedwetting to stop. We have a doctor’s appointment in 5 weeks, and I’m curious to see how her rectum compares to when she started treatment.

A: If your daughter’s bedwetting hasn’t diminished in five more weeks, I think it’s reasonable, though not necessary, to ask for a follow-up x-ray. Just know that enuresis doesn’t stop on a schedule. Typically, it takes about three months for the rectum, once emptied, to shrink back to size and stop encroaching upon the bladder. But even then, the bladder nerves can remain aggravated for a while. Whether the child continues to have accidents depends largely on how sensitive that child’s bladder is to encroachment by the rectum. Children who start with both encopresis and enuresis typically need a longer treatment period than children with bedwetting alone. So, you're on the right track in trying to be patient!

READ: The “Long Lag”: Why Bedwetting Takes Longer to Fix Than Daytime Accidents

If you do get an x-ray and it shows your daughter’s rectum is empty, you might discuss bladder medication with your doctor. There are three categories of medication. Bladder meds, when they work, can provide a psychological boost to the child while you continue treatment and wait for the rectum and bladder to heal completely.

READ: Bedwetting Medication: When It Works, When It Doesn't