When should I consider referring a patient with suspected lactose intolerance to a specialist?

Consider referring a patient with suspected lactose intolerance to a specialist if:

• There is diagnostic uncertainty or atypical symptoms that do not clearly fit lactose intolerance.
• Symptoms persist despite appropriate dietary modifications or elimination of lactose-containing foods.
• There are red flag features such as faltering growth, severe gastrointestinal symptoms, or systemic signs that suggest alternative or more serious diagnoses.
• There is a need to differentiate lactose intolerance from other conditions such as cow's milk allergy or coeliac disease, which may require specialist assessment and testing.
• There is suspicion of multiple or complex food allergies, or if the patient has significant atopic eczema or concurrent asthma, which may complicate diagnosis and management.

Referral is usually to a gastroenterologist, dietitian, or allergy specialist depending on the clinical context and local pathways.

In primary care, initial management includes dietary advice and trial elimination of lactose, but if symptoms do not improve or diagnosis remains unclear, specialist referral is appropriate to confirm diagnosis and guide management NICE CKS,NICE CG116,NICE NG20.