Drink more fluids. Water helps loosen mucus and soothe an irritated throat. Dry, hacking coughs respond to honey in hot water, tea, or lemon juice. Do not give honey to children younger than 1 year of age. Elevate your head with extra pillows at night to ease a dry cough. Try a cough drop to soothe an irritated throat.
That is actually true to a certain extent. Most of the time you need to have some sort of sensitivity/allergy to dairy. But dairy products can increase the thickness of your phlegm, therefore can clog up your sinuses, and eventually cause the sinus pressure.
My son was diagnosed with having a milk allergy. He gets rashes all over his cheeks, forehead as well as the back of his head. At first I thought it was just cradle cap, but no matter how much scrubbing, lotion and aquafore we put on it, it just wouldn't go away. I've since switched him to Soy formula and have limited the intake of dairy in my diet. (I'm nursing) So far his rash and fussiness has decreased. And I've noticed if I do intake a lot of dairy during the day, he doesn't sleep all the way through the night.