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 indicate lactose intolerance.
• Symptoms persist despite appropriate dietary modifications and 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.
• The patient has complex dietary needs or nutritional concerns requiring specialist dietetic input.

Referral is generally to a gastroenterologist or a dietitian with appropriate competencies to confirm diagnosis, exclude other conditions (such as coeliac disease or cow's milk allergy), and provide tailored management advice.

In primary care, initial management includes a trial of lactose elimination and symptom monitoring; if symptoms do not improve or diagnosis remains unclear, specialist referral is warranted.

This approach aligns with recommendations for referral in food intolerance and allergy contexts, where specialist assessment is advised for uncertain diagnosis, persistent symptoms, or nutritional concerns NICE CKS,NICE CG116,NICE NG20.