How can I check whether a protein powder is lactose-free?

Look for an explicit lactose-free statement on the selected product. Do not decide from “isolate”, “light” or low sugar content alone.

Check the ingredients and description for the specific flavour. Lactose-free and milk-protein-free are different requirements: a lactose-free product can still contain milk allergens.

For milk protein allergy, follow allergen labelling and professional advice. Ask for clarification before buying if the information is incomplete.