Lactose intolerance in neonates

Newborns normally take lactose from breast milk or standard formula. If lactose is not digested, stools may become loose and the baby may have wind, abdominal discomfort or feeding difficulty. In the first weeks of life, however, infection, swallowing problems, milk protein allergy, reflux and other conditions can look similar. Clinicians consider the baby’s age, birth history, feed volume, vomiting, stool appearance, temperature, weight and wet nappies before suggesting a feeding change.

Contact the newborn’s maternity, paediatric or primary-care team before changing formula or restricting foods. Continue feeds as advised and note how often the baby feeds, vomits or passes stool, along with wet nappies and alertness. Never add extra water or concentrate formula differently from the instructions. If a clinician suspects a temporary problem, they may arrange a monitored trial of a suitable feed and a review of hydration and growth. Food Intolerance Testing is not a substitute for an examination in a newborn. Nutrition Counselling may help when a medically supervised feeding plan is needed.

Seek urgent medical care for a temperature concern in a newborn, green or repeated vomiting, blood in stool, marked sleepiness, weak feeding, breathing difficulty, a swollen abdomen, very few wet nappies or a baby who is difficult to wake. These signs can signal dehydration, infection, obstruction or allergy and should not be managed at home as presumed lactose intolerance.

Ask what findings support the diagnosis, whether the baby needs weight or hydration checks, which feed is appropriate, and exactly when to return. Ask how to recognise worsening feeding or dehydration between reviews.