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Help! Autism-related picky eating keeps this teen constipated

“Our 13-year-old son has autism. Because he eats only certain foods, he’s always constipated. He’ll go two to three days without a bowel movement and then lose control in his pants. We’ve tried everything and don't know what to do. Desperate. Please help.”

Today’s “Food for Thought?” answer is from pediatric gastroenterologist Tim Buie. Dr. Buie practices at Massachusetts General Hospital’s Lurie Center for Autism. The center is one of 14 sites in the Autism Speaks Autism Treatment Network.

Editor’s note: The following information is not meant to diagnose or treat and should not take the place of consultation, as appropriate, with a qualified healthcare professional.

Thank you for reaching out with your question. You family is far from alone in struggling with this problem. I see two related but distinct issues to address here: your son’s picky eating and his chronic constipation.

Broadening food choices
First let’s discuss the pattern of extremely narrow eating you describe. As you may know, food aversions are common among children with autism. Research suggests that they cause problems for at least half of all children on the autism spectrum. Some studies put this at nearly 90 percent.

One careful study, at the New England Center for Children, suggests that restricted eating often eases as children with autism get older. That’s hopeful news for your teen. But based on the questions we receive from readers, we know that many older teens and even adults on the spectrum continue to struggle with this issue.

We also know that the self-imposed food restrictions tend to produce diets high in refined carbohydrates and low in fiber – for example, white bread or crackers with processed cheese. This type of diet can, indeed, be constipating. Milk is another commonly favored food. It too can be constipating if it’s one of only a few foods in a child’s diet.

It’s important to appreciate that this type of highly restricted eating is a potential health issue in and of itself. In other words, it’s important to help children and teens include a healthy range of foods in their diets even in the absence of constipation or other GI issues.

To start, I recommend the Autism Speaks ATN/AIR-P Guide to Exploring Feeding Behavior in Autism, for perspective and tips. Download it free of charge here.

In addition, a number of ATN feeding experts have addressed questions similar to yours in previous posts to this advice column. You can read their archived advice here

Many speech therapists and occupational therapists have training and experience with autism-related feeding issues – particularly when food aversions involve sensory issues.

Behavioral therapists, in turn, can work on expanding food acceptance with gradual exposure. You may even be able to get feeding therapy added to your child’s individualized educational plan (IEP). This can be an extremely helpful in helping him work on feeding issues during the school day as well as at home. Children are often more willing to try foods outside the home, especially when a teacher, teacher’s aide or therapist is encouraging them.

In addition, many pediatric medical centers – including those in the Autism Speaks Autism Treatment Network – have exceptional feeding programs that help children broaden their diets in healthful ways.

Easing constipation
Expanding your son’s food choices should help ease his constipation. In particular, it can help to increase his intake of dietary fiber. Foods high in dietary fiber include whole-grain products and fresh produce – both fruits and vegetables.

Also very important: increasing your son’s daily intake of liquids beyond milk. As a general guide, children ages 9 to 13 need around 6 or 7 cups (50-60 ounces) of fluid each from drinks, in addition to the fluid they get in food. But this varies according to a child’s weight. So I encourage you to discuss fluid intake with your son’s doctor.

Some families turn to fiber supplements such as psyllium or methylcellulose powder. But there’s little evidence that these products offer long-term help with constipation.

Autism and constipation: beyond diet
We commonly see a number of issues contributing to constipation in children with autism. Beyond diet, these include sensory issues and problematic toileting habits. I strongly recommend that you work with a health care provider comfortable and knowledgeable about these issues.

For instance, I often see physical discomfort triggering toileting problems in my patients. Simply put, it can be painful and difficult to pass hard stool. To avoid the pain, the child – or adult – begins to avoid bowel movements.

But the longer a person goes without a bowel movement, the stronger the colon contracts to move the stool into the rectum (the pouch between the colon and the anus). Stool then builds up in the rectum till it starts to leak – producing the incontinence, or soiling, you describe. In extreme cases, the result is rectal prolapse where portions of rectal tissue push out of the anus and partially block it.

Unfortunately, this can become a self-reinforcing cycle. Often we see patients with autism who have adopted the habit of making bowel movements only in their pants – typically standing or hiding in a private place.

This type of “stool withholding” behavior is one of the last things to get better because it takes a period of time of having non-painful bowel movements before the child – or adult – begins to relax and trust that passing stool won’t hurt.

So finding a treatment that allows your son to have pain-free and regular bowel movements is the priority. Again, I encourage you to work with a health care provider – be that his primary care physician or a gastroenterologist.

The first step may need to be a “clean out” the hard stool that has built up in the colon. Typically, this is done with repeated doses of a laxative such as magnesium, polyethylene glycol-3350, senna or another agent. Preferences differ among health care providers.

The next step is to achieve daily regularity. This may include the careful use of one of the laxatives described above, combined with dietary improvements and adequate fluids.

At the same time, it’s vitally important to establish a daily – or close to daily – schedule for using the toilet. Only with regular bowel movements can we avoid the hard stools that cause pain. In my experience, even one hard stool can trigger a child’s return to the withholding cycle.

Establishing a toileting routing
To establish a daily toileting routine, I suggest having your son sit on the toilet several times – even if it’s just to get comfortable with the sitting process. Be supportive. If he doesn’t go, that’s okay. If at first, he insists on going in his pants, at least have him do so while standing in the bathroom. Then take small steps toward sitting – for instance, have him stand closer to the toilet.

The Autism Speaks ATN/AIR-P Toilet Training tool kit is a practical and helpful resource for establishing daily habits. You can download it free of charge here.

However, it’s important that your son can make a bowel movement without pain before approaching this issue with a strictly behavioral approach. In my practice, I often work closely with my patients’ behavioral therapists. Ideally, your son’s behavioral therapist can work in tandem with his doctor. Once medical management gets the stools passing easily, the behavioral therapist can work with you on overcoming your son’s withholding behavior and establishing a successful toileting program.

Thank you again for reaching out with your question. Please let us know how you and your son are doing in the comment section below or by emailing us again at

For more GI-autism advice and perspective from Dr. Buie, see his Autism Speaks “Office Hours” video and Q&A series here.


* Learn more about the Autism Speaks Autism Treatment Network here.
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* Explore our archive of ATN expert-advice blogs and news stories 

The Autism Speaks blog features opinions from people throughout the autism community. Each blog represents the point of view of the author and does not necessarily reflect Autism Speaks' beliefs or point of view.