The symptoms of infant milk formula lactose intolerance typically manifest in the following areas:

Firstly, the most direct symptom is abnormal stool in infants, which looks poorly digested with more milk curds, and this is the most common direct symptom.

Secondly, the baby may experience increased gastrointestinal gas, bloating, abdominal pain, leading to restless sleep and irritability.

Furthermore, the baby may exhibit a decreased appetite and varying degrees of vomiting. Of course, most cases of infant lactose intolerance occur after an intestinal viral infection, so there may also be symptoms related to viral intestinal infections.