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Miralax Safety, X-rays for Constipation, and Laxative Timing: Enuresis and Encopresis Q&A

By Steve Hodges, M.D.

Is Miralax safe to take for short periods? Should my child be x-rayed for constipation? What’s the best timing for laxatives? My 7-year-old knows better than to pee in his pants — is he being lazy?

These are among the dozens of questions posted this week in our private Facebook support group. They’re also topics that frequently surface in my clinic. Below, I answer these questions in their full context and provide links to more detailed information.

Q: My 6 y.o. has always wet the bed and now has daytime wetting. I always blamed other issues, like a new sibling, grandparent death, or sleep issues. We did occasional Miralax, per the pediatrician, but never thought she was truly constipated. She did have big poops every other day but no tummy complaints. An x-ray 4 months ago showed constipation, so we started daily Miralax. Pee accidents continued, then poop accidents started. We did a Miralax clean-out with 9 caps of Miralax and 5 Ex-Lax squares. I expected more output. We are fed up with Miralax and now trying Ex-Lax. I’d prefer suppositories but have to fight our daughter to do that. Can you tell from our x-ray, taken after the clean-out, how dilated or damaged her rectum is?

A: Consistent with your daughter’s symptoms, the x-ray shows constipation. It looks like the Miralax clean-out just moved the poop downstream, as commonly happens. Her rectum is enlarged, but with more aggressive treatment, it will shrink back to normal size, and her accidents will stop. I wouldn’t worry about “damage.”

Everything you describe is classic constipation. Large poops are the #1 red flag, and many constipated children never complain of tummy aches. Life stressors and sleep issues don’t cause enuresis.

Backing off Miralax is a good idea, as osmotic laxatives often create more mess for children with encopresis. An enema-based regimen will more effectively clean out the rectum than Ex-Lax alone, but we never recommend forcing a child to do enemas. The child’s buy-in is important. Instead, we suggest planting the idea and letting it percolate. To the surprise of their parents, most kids come around!


The Enema Rescue Guide, included in the M.O.P. Anthology 5th Edition, offers 12 creative and practical strategies to help children overcome apprehension about enemas.

Bedwetting and Accidents Aren’t Your Fault, aimed at children ages 4 to 10, explains enemas to kids. “When laxatives and clean-outs didn’t work, my son was prepared for enemas,” posted one mom, who read the book multiple times with her son prior to trying M.O.P.

Emma and the E Club was inspired by a 7-year-old named Eden who had encopresis and was fearful of enemas. Eden made a video encouraging other kids to try enemas, and her mom posted the video on our private Facebook page. You can read about Eden and the book here.

Q: I know you say accidents are not a behavioral problem, but my 7 y.o. doesn’t seem to care that he is still in diapers. He is a very intelligent and has no problems in other areas. How can I address this? He knows very well he shouldn’t pee in his diaper. Is he being lazy, maybe?

A: Accidents have nothing to do with laziness, I assure you! In children with enuresis and/or encopresis, the signals to pee and poop have gone haywire. Truly, your son has no control over his accidents. His enlarged rectum is aggravating his bladder nerves, causing his bladder to “hiccup” forcefully and empty without warning.

All this is hard for parents to understand, since it's outside our experience. We may perceive a child who is “old enough to know better,” but knowledge and intelligence have no bearing on whether a child has accidents.

I wouldn't assume your son is unconcerned about his accidents, even if that's what you observe. Children care a lot more than they let on and feel deeply embarrassed, according to pelvic floor therapists who work with children.

“Kids worry they'll get in trouble or that their parents will be disappointed in them,” Tara Galles, a pelvic floor therapist in Indiana, told me. “Even though most parents try to avoid shaming their children, kids feel humiliation nonetheless."

I suggest focusing on your son’s treatment rather than his frame of mind. Once his rectum and bladder nerves recover, his accidents will stop, and everything will fall into place.


Q: My kindergartner had poop accidents daily for 2 years. (No bedwetting.) Her pediatricians recommended Miralax. We spent a lot of time begging her to sit on the potty and hiding Miralax in her beverages. Currently, we are in Phase 1 of Standard M.O.P. Her accidents stopped, but after a travel weekend without enemas, soiling occurred. I have several questions:

#1: What is the best timing for her regimen? I administer her enema before school, when she’s most receptive. Should we aim for an evening spontaneous poop? When should we do the osmotic laxatives? I worry that a morning laxative could cause an accident at school.

A morning enema and an evening spontaneous poop is a great schedule. Kids who poop twice a day will make more progress than kids who only poop after the enema, as explained in the M.O.P. Anthology, and spacing the two poops as far apart as possible is ideal.

The timing of an osmotic laxative doesn’t matter, because these laxatives only soften poop; they don’t stimulate a bowel movement. However, many children with encopresis do better without any osmotic laxative, at least in the early phases of treatment. Miralax can cause a mess in clogged-up kids.

A senna-based stimulant laxative such as Ex-Lax will more effectively trigger that evening bowel movement. She’ll need to take the Ex-Lax in the afternoon (possibly at school) and take a strong enough dose so that she poops within 5 to 8 hours. You may need to experiment with Ex-Lax timing on the weekends.


Stimulant Laxatives: Options, Timing, and Dosing, Section 6, The M.O.P. Anthology.

Osmotic Laxatives: Options, Timing, and Dosing, Section 6, The M.O.P. Anthology.

#2: Suggestions on osmotic laxative types? I'm concerned about Miralax side-effects, but maybe it’s OK for a short period?

In my experience, most kids experience no side-effects from Miralax, and so far, studies have not found a causal link between PEG 3350 and the aggression, mood swings, and other concerning behaviors that many parents have reported. However, no parent who is uncomfortable with PEG 3350 or worries about Miralax safety should feel compelled to give it to their children. The alternatives — including lactulose, magnesium hydroxide, and magnesium citrate — are plenty effective. But again, your daughter and other children with encopresis may be better off without an osmotic laxative at all, at least in Phase 1 of M.O.P.


#3: Next steps? Am I correct my daughter should have two daily bowel movements (post-enema and spontaneous) and no accidents before we progress to Phase 2?

She doesn’t necessarily need to have a daily spontaneous poop before you move on to Phase 2. We recommend tapering after the child has had at least 30 consecutive days of enemas and is “reliably accident free,” roughly defined as accident free for at least 7 days and nights. However, we do find that kids who have spontaneous poops before tapering are less likely to have a recurrence of accidents.

It sounds like your daughter isn’t reliably accident free, since soiling resumed after she missed a weekend of enemas. Many families define “reliably accident free” as three or four weeks accident free. Children with encopresis are particularly prone to refilling quickly, so tapering slowly is a good idea.


The Slow Taper: An Alternative Plan for Weaning off Enemas, Section 4, The M.O.P. Anthology.

#4: Should I request an x-ray?

We don’t recommend x-rays for encopresis, since chronic constipation is the only explanation for poop accidents. Any child who is having poop accidents is necessarily constipated, so an x-ray won’t tell you anything you don’t already know. With bedwetting or daytime wetting, we have more reason to x-ray, as explained in the Anthology.

HELPFUL READING: Seven Reasons to X-Ray for Constipation, Section 7, The M.O.P. Anthology.


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