What is the recommended treatment for lactose intolerance in an 18‑month‑old child?

Treatment for Lactose Intolerance in an 18-Month-Old

For an 18-month-old with lactose intolerance, dietary modification with temporary reduction (not complete elimination) of lactose-containing foods is the primary treatment, combined with nutritional counseling and regular growth monitoring to prevent calcium and vitamin D deficiency. 1, 2

Primary Management Strategy

Dietary Modification Approach

• Reduce but do not completely eliminate lactose from the diet, as complete restriction is rarely necessary in young infants and toddlers 2, 3
• If the child has acute diarrhea with suspected secondary lactose intolerance, temporarily switch to lactose-free or lactose-reduced formulas until symptoms resolve 1, 2
• Most lactose intolerance in this age group is secondary to underlying conditions (viral gastroenteritis, giardiasis, celiac disease) and improves once the primary condition resolves 4

Tolerable Dairy Products

• Yogurt and hard cheeses are generally well-tolerated even in lactose-intolerant children because they contain lower lactose levels and beneficial bacteria that aid digestion 1, 2
• These should not be eliminated unnecessarily as they provide essential calcium and nutrients 1

Nutritional Counseling Requirements

Mandatory Monitoring

• All children with lactose intolerance require nutritional counseling and regular growth monitoring to prevent nutritional deficiencies 5
• Children with milk restriction are at significant risk for inadequate calcium and vitamin D intake, which can affect growth 5

Calcium and Vitamin D Supplementation

• Children avoiding dairy products should receive calcium-fortified soy beverages or safe infant/toddler commercial formulas 5
• Vitamin D supplementation of 400 IU/day is recommended for all infants and children, with the recommended daily allowance being 600 IU/day for those aged 1 year and older 5
• Nutritional counseling significantly reduces the risk of consuming less-than-recommended calcium and vitamin D levels 5

Clinical Considerations for This Age Group

Rule Out Secondary Causes First

• At 18 months, lactose intolerance is typically secondary to an underlying gut condition rather than primary lactase deficiency, which generally does not manifest clinically before 5 years of age 4
• Investigate for viral gastroenteritis, giardiasis, cow's milk enteropathy, celiac disease, or other mucosal diseases 1, 4
• Secondary lactose intolerance is transient and improves with resolution of the underlying pathology 4

Distinguish from Cow's Milk Allergy

• Do not confuse lactose intolerance with cow's milk allergy (CMA), as they require completely different management approaches 4
• The majority of infants with CMA can actually tolerate lactose, except when an enteropathy with secondary lactase deficiency is present 4
• If CMA is suspected in a breastfed infant, implement a strict cow's milk protein-free maternal elimination diet; if formula-fed, use extensively hydrolyzed or amino acid-based formula 4

Practical Treatment Algorithm

Step 1: Dietary Trial

• Implement a 2-week dietary restriction trial with lactose reduction (not elimination) and monitor for symptom resolution 1
• Continue breastfeeding if applicable, as physiological lactose malabsorption in infancy confers beneficial prebiotic effects 4

Step 2: Lactase Supplementation (If Needed)

• Lactase enzyme supplements may be used to supplement the diet if dietary modification alone is insufficient 6, 7
• Lactase-treated dairy products can be offered as an alternative 7

Step 3: Growth Monitoring

• Monitor height-for-age percentiles, as children with milk restriction show lower growth parameters compared to those without dietary restrictions 5
• Ensure adequate protein intake, as children with milk allergy/intolerance tend to have lower protein intake (39g vs 48g in healthy children) 5

Critical Pitfalls to Avoid

• Do not completely eliminate all dairy products without nutritional counseling, as this significantly increases risk of calcium and vitamin D deficiency affecting growth 5
• Do not rely on parental reports of lactose intolerance alone without dietary trial or objective testing, as self-reports correlate poorly with actual lactose malabsorption 1, 2
• Do not assume primary lactase deficiency at this age—investigate and treat underlying conditions first 1, 4
• Ensure the child receives adequate nutrition from alternative sources if dairy is restricted, as children with multiple food restrictions are at higher risk for inadequate nutritional intake and shorter stature 5