Milk Allergies and Constipation

Milk is a major part of most children’s diets. If a child is intolerant to milk, this can affect how they feels every single day of their life.

Question

Dr. Greene, our 19-month-old son has seemed to have trouble since his birth. He wouldn't be miserable all the time, just a good portion of the time. At 1 year, he was introduced to cow's milk. Before this time, he had consumed cheese and a few other dairy products. He is a very unsettled, miserable-acting child. As his mother, I know something is wrong. He has been having trouble with constipation for a while now. We have tried increasing fruit, veggies, and whole grains to no avail. He goes for days between stools, and when he does eliminate, there is a very hard, very large "plug" of stool that comes out, followed by two to five diapers full of loose stool within a couple of hours. His father is lactose intolerant yet can drink skim milk with no problems. My question is: should we try skim milk? Or should we try a lactose-free type of milk or soymilk? Any help would be appreciated greatly!!!
Shannon - Woodstock, Nebraska

Dr. Greene`s Answer:

A cranky, unhappy toddler may well be responding to physical discomfort. Tummy troubles of one type or another can make anyone feel miserable. Milk is a major part of most children’s diets. If a child is intolerant to milk, this can affect how he feels every single day of his life. Nausea, cramps, and pain can squelch the normal joys of discovery and mastery.

Symptoms of Milk Allergies

But the classic symptoms of milk intolerance are diarrhea, spitting up, or abdominal pain. Many kids with milk intolerance also wheeze, especially when they get a cold. They can also have the dry, sensitive skin of eczema and their noses always seem to be running. Ear infections are also more common than in other kids. Constipation, however, has not been typically associated with milk intolerance — until now.

The observation that constipation might sometimes be caused by milk intolerance has appeared in the medical literature from time to time, dating back as far as 1954. But only recently has there been a well-designed study published showing that this is indeed the case. The results of this study have helped many children to enjoy the exuberance of childhood without pain.

Studying Milk Allergies and Constipation

Researchers at the University of Palermo in Italy worked with 65 children with chronic constipation. All of these children had been treated with laxatives when dietary measures had failed. Even with the medical treatment, these children were still constipated, having hard, painful stools only every 3 to 15 days. Forty-nine of their little bottoms had fissures and redness or swelling from the hard plugs of stool.

Each child received either cow’s milk or soymilk for 2 weeks, with no one knowing which was which. Next, they had a week during which they could eat and drink anything they wanted to wash out the effects of the first 2 weeks. Then they switched sides for 2 weeks and got the milk that they didn’t get the first time. Careful recordings of the bowel habits were made.

When the secret code was broken at the end of the study, they found status quo constipation for each child while he or she was on cow’s milk. But while they were taking soymilk (which causes firmer stools in most kids), 68% of these kids were no longer constipated! The redness, swelling, and fissures on their bottoms healed. How wonderful to finally have relief after diet and medicines hadn’t worked for so long!

The results were most dramatic in kids who also had frequent runny noses, eczema, or wheezing. Nevertheless, sometimes constipation can be the only symptom of cow’s milk intolerance.

Treating Milk Allergic Kids and Constipation

This has broad implications. The children in this study were those with severe chronic constipation that was unresponsive to medications. I am convinced that they are only the tip of the iceberg. There must be a much larger group of mildly allergic children whose constipation improves with laxatives. Time may prove that it is better for these children to avoid the offending protein by switching milks rather than being treated with laxatives.

Presumably, swelling of the intestinal lining causes the constipation. Whatever the exact mechanism, the problem is likely with the protein in cow’s milk, not with the fat or lactose (the sugar). Skim milk or lactose-free milk will not help with this one. Switching to soymilk and other soy products might transform the life of your son in only a couple of weeks!

These same ideas also apply to infants who may be experiencing constipation related to their milk-based formulas. In the past, low iron formulas had been recommended for constipation. However, starting in 1999, the American Academy of Pediatrics (AAP) Committee on Nutrition declared that constipation is not a contraindication to iron-fortified formulas and that, in fact, lowering the iron content causes more harm than benefits.  

First, let’s address the iron in formula and constipation question. Some people will (or have) told you that the iron is the problem and that switching to a low-iron formula will help. It makes sense, because when adults take iron supplements, we get constipated as a side effect. But there was a study done concerning the formula and constipation question in babies. Half got low iron, half got regular (not knowing which was which) and the rate of constipation was the same in both groups. For most kids, that does not make a difference, and the iron is very important for growing babies.

The constipation can be formula-related, though. Allergies to some of the proteins in the formula could cause the discomfort. Sometimes switching to another brand will help (the milk-based formulas are not all the same). Sometimes switching to soy will help (just as we saw in the study above). All other things being equal, soy makes stools firmer; but for kids with an isolated allergy to milk protein, the constipation may dramatically clear up on soy.

Unfortunately, some children are also soy protein intolerant. As it happens, this is more common in kids who are allergic to cow’s milk protein. If you don’t get good results within two weeks, I suggest also eliminating soy from the diet and trying Alimentum or Nutramigen (protein hydrolysate infant formulas) for two weeks. Because the proteins in these formulas are broken down, your son is less likely to be allergic to them. If they work, you can then experiment with other sources of calcium, protein, and fat for the future (perhaps fortified rice milk). 

It’s not that common for simple changes to relieve relentless, longstanding problems. But when a child is made miserable by an allergy, removing the source can result in a rapid, dramatic improvement in the quality of life. I hope, Shannon, that this turns out to be the case with your son and that this next season his smiles double to make up for those he has missed.

Resources and References

Committee on Nutrition. Iron fortification of infant formulas. Pediatrics. July 1999, 104 (1) 119-123.

Dehghani SM, Ahmadpour B, et al.  The role of cow’s milk allergy in pediatric chronic constipation: a randomized clinical trial. Iran J Pediatr. 2012;22(4):468-474.

Iacono, G, et al.  Intolerance of cow’s milk and chronic constipation in childrenNew England Journal of Medicine. 1998; 339:1100-1104. 

Last medical review on: April 05, 2021
About the Author
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Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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Recent Comments

nice article, if anyone has the problem of constipation they should try a2 milk instead of normal milk it contains lactose so it is easy to digest.

At age 16 I started showing symptoms of chronic constipation and eczema. By age 18 the symptoms were absolutely unbearable. The eczema was so bad the doctor thought it was a rash associated with ringworm. It was only in small patches but had a very particular (circular) shape. The constipation was awful. No brand of laxative helped. Not a single one. Not even the ones they use after surgery. The only thing that helped was consuming linseeds that had been soaked in water overnight – worked a dream. Age 18 I eliminated dairy from my diet (after 10 GPs and 1 Dietician were utterly no help, one even said I was making it up). I cannot emphasise enough how much eliminating dairy has worked. Age 23 I’m still happy!

Have you tried A2 milk? It has a different composition from most of the milk in the US. It started with the cows in New Zealand. The A2 milk there was tolerated by some people who couldn’t drink other cow milk. It’s available in some Australia and US locations, but you may have to ask your local grocery store to carry it. In California, some Safeway stores carry it, but I think you need to ask them to order it. It’s what I drink.

Might we worth a try.

Hi, My 2 year old son seems to have always had trouble with milk — of all sorts. While breastfeeding I had to go off dairy because of his GERD and belly aches. He had earaches almost monthly after switching to milk-based sensitive formula at 6 months and had to take miralax daily for 3 to 6 months after that. Now we can’t seem to get him straightened out — he’s either got diarrhea or he’s constipated. There is no happy medium. He won’t drink soymilk except as a last resort and is constipated when he does. Almond milk seems to be an allergy and he won’t drink it either (diarrhea if he does). Lactose free milk didn’t solve the problems but he would drink it. He loves milk. We tried 2% milk but that causes constipation. Whole milk leads to diarrhea. We’re currently mixing the two, but we haven’t gotten the proportions right yet. He eats poorly and is very low in terms of BMI and weight percentage. Any suggestions/advice would be greatly appreciated! Thank you!

Have you tried A2 milk? It has a different composition from most of the milk in the US. It started with the cows in New Zealand. The A2 milk there was tolerated by some people who couldn’t drink other cow milk. It’s available in some Australia and US locations, but you may have to ask your local grocery store to carry it. In California, some Safeway stores carry it, but I think you need to ask them to order it. It’s what I drink.

Might we worth a try.

Hello Gwen ….you just switched your kid to rice milk????

Wow, that sounds painful. And sounds like it’s time to try one of the truly easy to digest formulas like Nutramigen. What is your child’s doctor suggesting?

Hi my child is 4 months, i have changed her milk numerous times. Her last visit to the Ped they moved her to Simalac Soymil, its been 2 weeks now she is very badly constipated she is consistently in pain, i had an xray done the stools are all hard in her tummy causing unbearable pain. Please can you advise maybe this milk is not agreeing.

Wow, that sounds painful. And sounds like it’s time to try one of the truly easy to digest formulas like Nutramigen. What is your child’s doctor suggesting?

I use to give nido fortified milk to my 5 yrs old baby.. she has great problem of constipation for last 2 yrs.. do u think milk causing yhis constipation.

Thank you.

Mine is 7 years now, and she is categorized as autism. I always believe that there is a missing puzzle piece as her main problem is communication. She has flashes of communication — she can say something today and go for 3 months before flashing another sentence.

Lets try this, hope it will work for her.

*Cows milk (typing on the iPad) I apologize for the typos.
-These episodes have occurred every 2-3 months and I’ve not been able to send her to school for day once for 2 days. In between episodes she’ll go 3-5 days without a B.M.