Add 5 drops to 1 litre of milk or any other liquid, non-acidic dairy product. Stir well and leave in the fridge for 24 hours. At least 80% of the lactose will have been broken down by this time. Add more drops for a higher rate of conversion. Do you want to use the product immediately without waiting? Then add 5-10 drops per 120ml of milk product. Do not use with acidic dairy products such as yoghurt and buttermilk.