A Japanese Twist on Bedwetting Treatment: Olive Oil Enemas for Severe Constipation
- Dec 7, 2023
- 5 min read
Updated: 6 days ago
By Steve Hodges, M.D.
This blog post was updated in 2026 to reflect Dr. Hodges' current treatment recommendations.
Some children continue to struggle with bedwetting, daytime wetting, or poop accidents even after months of treatment for constipation, the underlying cause of all three conditions. Parents are told the child is “no longer constipated,” yet the accidents keep happening.
In many of these cases, an abdominal x-ray shows the real problem: the rectum never fully emptied. Hardened, old stool remains stuck inside, keeping the rectum stretched and irritating the nerves that control the bladder and bowel.
In the most stubborn cases, that stool can seem practically Super-Glued in place.
These are the kids who have tried everything — even a daily enema regimen such as the Modified O’Regan Protocol (M.O.P.) — and still aren’t dry. The problem isn’t lack of effort. The problem is that the stool has become so dried out and compacted that standard treatments can’t clear it completely.
As long as the rectum stays stretched, accidents often continue, no matter what else you try.
For these cases, I sometimes recommend a more aggressive but surprisingly simple approach: soften the stool overnight with an olive-oil enema, then stimulate full evacuation twice a day using glycerin-and-water enemas.
This method is based in part on treatment approaches commonly used in Japan for severe constipation and fecal impaction. All you need are olive oil, liquid glycerin, water, and a syringe — no store-bought enemas required. Because the idea grew out of research from Japan, I refer to this protocol as J-M.O.P.
J-M.O.P. has helped many of my patients who did not respond to standard treatment. In this article, I’ll explain the research behind this approach and why it can work when other regimens fall short.
Detailed instructions, dosing guidelines, and tapering plans are included in the M.O.P. Anthology, which explains all the M.O.P. variations and when to use each one. (Many children need to try more than one approach before the rectum finally empties and stays empty.)
Heads up: This post assumes you’re familiar with enema-based treatment in general and with M.O.P. in particular. If this is new to you, start with these posts:
Why some kids stay clogged despite treatment
The goal of treatment for accidents is straightforward: the rectum must empty completely and remain empty long enough to shrink back to normal size and regain normal tone and sensation. (Once the rectum is empty, the healing process that takes a good three months.). When the rectum has healed, the child can fully sense the urge to poop again, the bladder nerves calm down, and accidents stop.
For most children, daily enemas, stimulant laxatives, or other tools described in the Anthology are enough to get there. But some kids — especially those with years of constipation behind them — remain partially clogged.
In these cases, stool can be almost welded inside the rectum.
The problem isn’t lack of effort. These families tend to be quite diligent about treatment. The problem is that the stool has become so firm and compacted that standard regimens don’t clear it completely.
So, what does it take to dislodge a stool pile-up that stubborn?
In my experience, two things must happen:
• The stool must be softened with something more effective than an oral laxative
• The rectum must be stimulated to empty completely twice a day
That’s where the combination of overnight oil enemas and glycerin-water enemas can make a big difference.
For years I’ve recommended overnight oil enemas for the toughest cases of constipation. Oil retention enemas are an old-school treatment — doctors were using them in the 1800s — and they work extremely well for softening hardened stool.
An 1892 medical journal described olive-oil enemas as a “safe method of relieving even the most obstinate cases of spasmodic constipation,” and my experience has been the same.
More recently, a 2020 study from Japan confirmed this. In a paper titled The usefulness of olive oil enema in children with severe chronic constipation, pediatric surgeon Dr. Akiko Yokoi reported excellent results using oil enemas in children with fecal impaction.
I’ve written about that study here.
What caught my attention even more, though, was how glycerin enemas are used in Japan.
In the United States, glycerin enemas — sold as “liquid glycerin suppositories” (LGS) — are given in very small volumes. These work well for many children and are one of my preferred treatments because they’re gentle, effective, and inexpensive.
But in Japan, doctors commonly use enemas that are half glycerin and half water, and in larger volumes than we typically use in the U.S.
In Japan, these glycerin-water enemas are commercially available in several sizes and are routinely used for children with severe constipation. That made me curious.
If stronger glycerin enemas can produce a more complete evacuation…and oil enemas effectively soften hardened stool… what would happen if we combined the two?
I contacted Dr. Yokoi to learn more about how her hospital uses the 50/50 glycerin-water enemas. She told me she has no safety concerns about using glycerin in higher volumes than we use in the United States, even more than once per day if needed.
“We frequently use glycerin enemas and generally find them very effective,” she told me.
That matched what I had been seeing in my own patients, and it was a refreshing perspective. In North America, Europe, and Australia, enemas are often described as “traumatic” or “overly aggressive,” and doctors tend to rely on oral laxatives such as Miralax even when the child clearly isn’t getting empty.
In Japan, the approach is different. When stool is impacted, the goal is to clear it — completely — and enemas are the go-to treatment in children's hospitals.
After my discussion with Dr. Yokoi, I began using a regimen that combines overnight oil enemas with higher-volume glycerin-water enemas during the day, especially for children whose x-rays still show stool in the rectum after weeks of treatment.
For many of my most stubborn cases, this has turned out to be the missing piece.
The Japanese-style enemas seem to hit a “Goldilocks” zone — strong enough to produce a full evacuation but not so large that they overstretch the rectum the way large-volume bag enemas sometimes can. When the stool finally softens and the rectum finally empties, accidents start to improve.
This is why I now include this variation — J-M.O.P. — as one of the options described in the M.O.P. Anthology.
Not every child needs this approach. But if enuresis or encopresis persists despite daily enemas, stimulant laxatives, or other standard treatments, it usually means the rectum is still not empty. In those cases, a stronger regimen may be necessary.
The M.O.P. Anthology explains how to recognize when treatment isn’t working, when to change course, and how and when to taper off treatment, including the oil-plus-glycerin-enema regimen described here.
Children often don’t improve until the right regimen is found. Parents need not worry — the goal isn’t to do enemas forever. The goal is to empty the rectum completely so it can heal, accidents can stop, and the child can move on with life.