I am unaware of the evidence for avoiding dairy to alleviate sinusitis. Your doctor probably thinks that a dairy allergy is leading to the sinusitis and laryngitis. If this is the case then you need to avoid ALL dairy, including any dairy that is added to other foods. A dairy-free diet contains no milk, cheese, butter, cream cheese, cottage cheese, sour cream, ice cream, whey, casein, or foods that contain any of these ingredients. Please see our Health Notes Section online for Dairy-free diet ideas and foods to avoid. Dairy products are a great source of calcium, so you may want to consider taking a calcium supplement to prevent any deficiencies. Wellness Warehouse has a great selection of dairy-free alternatives as well as an extensive supplement range. Good luck.