Lactose intolerance is when a person can’t digest lactose, the sugar in milk products. Taking in milk products then causes intestinal discomfort. Symptoms of lactose intolerance vary but may include:

• Nausea
• Cramps
• Bloating
• Gas
• Diarrhea

Symptoms usually begin about 30 minutes to two hours after consuming lactose. The more lactose they eat, the worse the symptoms.

There are several ways a kid might become lactose intolerant. It’s usually to do with not having enough lactase. Lactase is an enzyme normally made in the small intestine.

Lactase breaks the double-sugar lactose into two smaller sugars that the body absorbs and uses for energy. If the body doesn’t break down the lactose, it travels to the large intestines. There, bacteria break it down, creating byproducts that irritate the gut. This can cause uncomfortable gastrointestinal symptoms.

They include:

• Lactase deficiency: Some kids don’t make enough of the enzyme lactase. Most children are born with enough lactase, but levels can slowly drop over time. This often begins after age 5 and continues into the teen or adult years.
• Digestive diseases: Conditions like celiac or Crohn’s disease can damage the small intestine.
• Other causes of damage: Surgery, infection or inflammation can harm the small intestine.
• Reaction to a stomach virus: A common stomach bug can damage the small intestine.

Lactose intolerance may be temporary. This may be the case if your child’s symptoms follow a stomach virus or if they have damage to the small intestine. In these cases, symptoms often improve within a few weeks. We’ll help you decide when to safely reintroduce dairy.

If your child has a digestive disease that affects the small intestine, they may tolerate lactose again once the gut has healed.

If it doesn’t go away, your child might have lactase deficiency, which we also call primary lactose intolerance. For this, treatment usually starts with a two-week dairy elimination trial. That means avoiding all foods with lactose to see if your child feels better.

If your child’s symptoms improve somewhat, but it’s still unclear whether lactose intolerance is the issue, then the doctor may suggest some tests. This may include a biopsy to test enzyme activity in the small intestine or a breath test. The breath test measures the amount of hydrogen in the breath and helps diagnose several digestive problems, including carbohydrate intolerance, bacterial overgrowth of the small intestine and quick movement of food through the small intestine.

A lactose-free diet is often key to managing lactose intolerance. Our dietitians can help you choose milk-free foods while making sure your child still gets enough calcium.

Many children can still eat small amounts of lactose without symptoms. Hard cheeses (like cheddar or Swiss) and lactose-free milk are often well tolerated. Yogurt with live cultures may also be easier to digest.

Important parts of caring for a child with primary lactose intolerance include:

• Calcium and vitamin D support: Without dairy, kids may miss out on key nutrients for bone growth. Try calcium-rich dairy alternatives or supplements if needed.
• Lactase enzyme drops or tablets: Some kids can take over-the-counter medicines to reduce symptoms. These lactase enzyme products help break down lactose.
• Lactose reintroduction trials: Some kids can tolerate small amounts of lactose. Your care team may guide you through testing tolerance to certain foods.
• Monitoring growth and nutrition: Kids with dietary restrictions should have regular check-ins with their care team. We’ll make sure they’re growing well and getting what they need.

Avoiding dairy doesn’t help every child. Sometimes, symptoms come from a high-sugar diet, an imbalance in gut bacteria or another digestive issue. If that’s the case, we’ll help you explore other causes and next steps.