Dairy can certainly aggravate inflammation of the sinuses. I avoid dairy whenever I get sinus problems. When I start suffering from inflammation I stick to mostly ant-inflammatory foods: Dark leafy greens, broccoli, fish, garlic, chili peppers, horseradish, fruit turmeric, Indian food. If you are on aspirin, make sure you are not allergic to it. It often causes sinusitis. If you drink wine, keep in mind that sulfites can trigger sinus problems. There is sulfite-free wine.