Gastroenterologist (Pediatric) Questions Milk consumption

Can milk cause loose stool in kids?

My child often ends up getting loose stool soon after drinking milk. Why would milk cause this?

7 Answers

Intolerance to lactose causes diarrhea. Lactose is a natural sugar in cow's milk.
Lactose intolerance. Take Lactaid as needed when they have dairy.
This might be related to lactose intolerance.
The answer is yes. This happens by two main mechanisms. The first is lactose intolerance, or the inability to properly break down the sugar in milk called lactose. This can be diagnosed by testing, however, the easiest way is to allow your kid to have no diary for a few days, then give several ounces of a brand of milk called “Lactaid” (or similar). This milk has no lactose. If your kid tolerates this with no symptoms, then you have made the diagnosis. And if that is the case, avoiding dairy that has lactose is an appropriate way to proceed, or you may have your child take a tablet called “Lactaid,” which is the enzyme responsible for breaking down lactose. I personally take this when I am eating ice cream or other dairy.

The other way milk can cause diarrhea is by an intolerance (some would even say an “allergy”) to the protein in milk. This can be diagnosed the same as above with lactose intolerance, but the patient will get diarrhea with the Lactaid milk. The treatment is avoidance.

Hope this helps,

Albert G. Karam, MD
There are several reasons for having diarrhea, or other abdominal symptoms, such as abdominal pain, gas pain, even bloody stools or vomiting after the ingestion of milk. One of the most common ones is milk allergy, which can be an allergy to the cow's milk protein component in milk or lactose intolerance. Both can be tested, the first one by an allergist and the second one by a lactose intolerance breath test, performed by a pediatric gastroenterologist. Such children also usually have symptoms with the ingestion of other dairy products, such as yogurt, cheese, and butter. Taking the child off milk and milk products is usually effective after a specific diagnosis has been made. Soy milk is frequently a good substitute, though some children who are allergic to cow's milk are also allergic to soy milk. Almond milk and rice milk are well-tolerated.
Loose stools after drinking milk could be a sign of lactose intolerance. You should address this with your PCP and perhaps he/she can advise some solutions if lactose intolerance is strongly suspected.
The sugar in the milk, lactose, can cause diarrhea if your child lacks the enzyme to break it down. Also, some children with a milk protein allergy have diarrhea, but they also usually do not grow well and have a rash when they drink milk. You could try Silk soy or Lactaid milk.