Lactose Intolerance in Children: A Parent's Guide

If your child gets an upset stomach after dairy, lactose intolerance may be the cause. It's uncomfortable, but very manageable once you understand what's happening and it's easy to confuse with a milk allergy, which is a different condition entirely.

Does your child get stomach cramps or diarrhea after milk or ice cream? Our pediatricians can help you find out why. Call 703-344-7330 to schedule a visit.

Lactose intolerance happens when the body doesn't produce enough lactase, the enzyme needed to digest lactose (the natural sugar in milk and other dairy products). When lactose isn't broken down, it stays in the intestines and ferments, leading to gas, bloating, cramping, and diarrhea typically within 30 minutes to 2 hours of eating or drinking something with dairy in it.

This is not the same as a milk allergy. Lactose intolerance is a digestive issue; a milk allergy is an immune system reaction that can be more serious, including severe allergic reactions. A milk allergy tends to appear in the first year of life, while lactose intolerance more often shows up later, around school age or the teen years, though it can occasionally develop temporarily in younger children too.

Common Symptoms

• Stomach cramps
• Bloating and gas
• Diarrhea
• Nausea
  

It's rare for a baby to be born lactose intolerant. More often, a child develops temporary lactose intolerance after a stomach bug, a bout of severe diarrhea can briefly reduce the body's ability to produce lactase, causing trouble digesting milk for a week or two afterward. Longer-term lactose intolerance is often genetic and more common in some ethnic groups than others, and can also occur alongside conditions such as celiac disease.

One simple approach is an elimination trial: remove milk products from your child's diet for about two weeks to see if symptoms improve, then slowly reintroduce them to see if symptoms return. If needed, your pediatrician can also order a hydrogen breath test, the most common medical test for lactose intolerance, which measures hydrogen in the breath after your child drinks a lactose solution. In some cases, a referral to a specialist for further testing may be recommended.

Managing Your Child's Diet

If dairy is limited, other calcium sources matter. Foods like broccoli, beans, sweet potatoes, leafy greens, canned fish with bones, tofu, and calcium-fortified juice have high calcium. Recommended daily calcium intake increases with age (roughly 500 mg for ages 1–3, 800 mg for ages 4–8, and 1,300 mg for ages 9–18), and your pediatrician can advise whether a supplement makes sense for your child.

Think your child might be lactose intolerant?

Still have questions about your child's symptoms?

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