I strongly believe milk does increase mucous, but that's ok, I have no problem getting it out. But dairy products in general, I don't think they do but I do know they clog and congest your artieries, and I personally stay away from yogurt as it has aspartame. Whenver I go grocery shopping I read the ingredients before buying, if it contains aspartame, Splenda, or says "diet" or "sugar free", I stear clear.