Milk in the morning, stomach cramps by afternoon. Curd rice is fine, but a milkshake leads to loose motions. If this pattern keeps repeating, you may be dealing with lactose intolerance in children.
In India, dairy is part of daily food (doodh, dahi, paneer, lassi, sweets), so parents often worry about growth. The reassuring part: lactose intolerance in children is usually an enzyme (lactase) issue, often linked to portion size, and sometimes temporary after gastroenteritis. Many children can still have some dairy, comfortably.
What lactose intolerance in children actually means
Lactose is the natural sugar in milk. When lactase (the enzyme in the small intestine) is low, lactose is not fully digested.
Two terms help:
- Lactose malabsorption: lactose is not fully digested/absorbed.
- Lactose intolerance in children: malabsorption causes symptoms-bloating, gas, tummy pain, diarrhoea.
A child can malabsorb lactose and feel okay. Another may react strongly to a large dose. That’s why symptoms and patterns matter more than labels.
The gut science in simple words: lactase, osmosis, fermentation
Lactase sits on the brush border of the small intestine. It cuts lactose into glucose and galactose so they can be absorbed.
When lactase is low:
- Undigested lactose pulls water into the bowel (osmotic effect) -> loose stools.
- In the colon, bacteria ferment lactose -> hydrogen (sometimes methane) -> gas, bloating, cramps.
This also explains a common observation: curd/yogurt may be tolerated while plain milk triggers symptoms. Fermentation lowers lactose content and changes how quickly it hits the gut.
Types of lactose intolerance in children
Primary lactose intolerance (genetic lactase non-persistence)
Lactase is high in infancy and may gradually decline after early childhood. Symptoms of lactose intolerance in children often show up after about 5 years or during adolescence, especially with larger amounts (big glasses of milk, ice cream, milkshakes).
Secondary lactose intolerance (after illness or gut irritation)
After a stomach bug, the gut lining can be temporarily inflamed and make less lactase. This form of lactose intolerance in children is common and often improves as the intestine heals.
Secondary intolerance can also be linked to celiac disease, inflammatory bowel disease, or persistent infections.
Congenital lactase deficiency (very rare)
Symptoms start soon after feeds in newborns: severe watery diarrhoea and dehydration risk. Urgent medical assessment is needed.
Developmental lactase deficiency (premature babies)
In premature babies, lactase activity can be low due to gut immaturity, it usually improves with time.
Causes and risk factors
- Family history/genetics: makes lactose intolerance in children more likely.
- After gastroenteritis: a classic trigger for temporary intolerance.
- Celiac disease/IBD: damage or inflammation of the small intestine can reduce lactase.
- SIBO (small intestinal bacterial overgrowth): increases fermentation and gas.
- Antibiotics: may disturb gut microbiota and worsen symptoms in a borderline child.
Symptoms parents may notice
Symptoms are mostly digestive and often start within 30 minutes to 2 hours (sometimes up to 4 hours) after lactose.
Common signs of lactose intolerance in children:
- bloating, gas, rumbling sounds
- crampy tummy pain
- loose or watery stools, urgency
- nausea (more common in teens)
In babies and toddlers, frequent watery stools can be acidic and cause diaper rash or redness around the anus.
When to worry more (red flags)
Get medical advice promptly if your child has:
- dehydration (very less urine, dry mouth, unusual sleepiness)
- blood in stool
- persistent fever
- severe pain or vomiting that stops drinking
- weight loss, poor weight gain, slowed growth
- night waking due to symptoms
Lactose intolerance in children vs milk allergy and other look-alikes
Cow’s milk protein allergy (CMPA)
CMPA is immune-related. Along with gut symptoms, it may cause:
- hives, swelling
- eczema flare
- wheeze/cough/rhinitis
- repeated vomiting
If these happen, especially in infants, speak to a clinician.
Other possibilities
If symptoms continue even with lactose-free dairy, consider non-lactose triggers (fat, additives), functional abdominal pain/IBS, infection (including Giardia), or broader FODMAP sensitivity.
How lactose intolerance in children is diagnosed
A clinician usually checks:
- timing after dairy
- which foods trigger symptoms (milk vs curd/yogurt vs cheese/paneer)
- stool and pain pattern, hydration
- growth curve
- recent gastroenteritis or antibiotics
A simple trial: reduce and reintroduce
Often the first step:
1) Reduce lactose for 1-2 weeks (keep nutrition adequate).
2) Reintroduce small portions with meals.
3) Increase slowly to find the comfort zone.
Hydrogen breath test
After fasting, your child drinks a lactose solution and breath samples are taken for 2-3 hours. A rise in hydrogen supports lactose malabsorption.
Stool tests (younger children)
Low stool pH and reducing substances can suggest carbohydrate malabsorption, but results need clinical context.
If symptoms persist or growth is affected, screening for celiac disease may be suggested.
Day-to-day management that keeps life practical
Do children need to stop dairy completely?
Often, no. With lactose intolerance in children, the aim is comfort without weakening nutrition.
Helpful strategies:
- keep portions small
- spread dairy through the day
- give dairy with meals
- prefer lower-lactose options
Dairy choices that are often better tolerated
- curd/yogurt with live cultures
- aged hard cheese (naturally low lactose)
- lactose-free milk
Milk is often the biggest trigger because it delivers a larger lactose load quickly.
Lactase enzyme drops/tablets
Taken just before dairy, they can help during travel, parties, restaurants, or school lunches. Follow product instructions and confirm for young children with your paediatrician.
Lactose intolerance diet for children (India-friendly)
Higher-lactose foods that often trigger symptoms
- regular milk
- ice cream
- milk-based sweets and creamy desserts
- many soft cheeses
Lower-lactose choices
- curd/yogurt, kefir
- aged cheese
Hidden lactose
Lactose can appear in packaged foods and some medicines. A pharmacist can help check inactive ingredients.
Milk alternatives that support growth
Plant-based drinks differ a lot. For growth, check:
- protein
- calcium and vitamin D fortification
- added sugar (prefer unsweetened)
Fortified soy or pea-protein drinks are often closest to cow’s milk for protein. Almond/oat/rice drinks are usually lower in protein.
Nutrition and growth: what to protect
If dairy reduces significantly due to lactose intolerance in children, keep an eye on:
- calcium (bones/teeth)
- vitamin D (helps absorb calcium)
- protein and total calories
Calcium needs (approx.):
- 1-3 years: 700 mg/day
- 4-8 years: 1,000 mg/day
- 9-18 years: 1,300 mg/day
Protein options many Indian families use: eggs, dal, chana, rajma, lentils, fish/chicken, tofu, nut butters (age-appropriate).
After stomach bugs: temporary lactose intolerance
After gastroenteritis, lactase can drop while the gut lining heals. Symptoms often improve within 1-2 weeks.
Reintroduce step-by-step:
- start with small amounts with meals
- increase every few days if tolerated
- step back if symptoms return, use lactose-free products longer
Lactose intolerance in infants and babies
True long-term lactose intolerance in children starting in healthy infancy is rare. If a newborn has persistent watery diarrhoea soon after feeds plus dehydration signs, urgent medical review is needed.
Breast milk contains lactose and breastfeeding usually continues, feeding changes should be guided clinically.
Key takeaways
- Lactose intolerance in children is a digestion (lactase) issue, not an immune allergy.
- Symptoms are often dose-dependent and typically appear within a few hours of lactose.
- Primary intolerance is more common in older children/teens, secondary intolerance after gastroenteritis may improve.
- A short reduction and careful reintroduction often helps identify the tolerated amount.
- Protect nutrition (calcium, vitamin D, protein). Choose lactose-free dairy or fortified higher-protein plant options.
- Seek medical advice for dehydration, blood in stool, fever, severe pain, persistent vomiting, weight loss, poor growth, or night symptoms.
- Support is available through your paediatrician and dietitian, and you can download the Heloa app for personalised guidance and free child health questionnaires.
Further reading :
