Avoiding dairy isn't as simple as no longer drinking milk. Dairy is used in many different foodstuffs to give it a better taste. As such, you'll need to read food labels. Most foods that use some form of dairy, will list “milk” as an additive. The FDA requires that milk be listed under its provision for allergies. If milk isn't listed as an ingredient, you should be ok. You'll want to look for casein and whey as well. Both of these additives are proteins found in cow's milk and make their way into a variety of foods. Whey is used in a variety of products from muscle building supplements to canned chicken broth. This is often the hardest dairy category to give up because we are conditioned to enjoy milk with so many different foods. It becomes a part of our daily activities. Here are some of the most common milk- and cream-based foods:  Milk (whole, 50/50, skim, or condensed milk) Heavy whipping cream Custards Coffee creamer Cream sauces and soups Ice cream, gelatos, and sherbets (sorbets contain no dairy products) Yogurts Some mayonnaise, mustard, and other condiments Non-dairy coffee creamer. Casein is an animal byproduct so it won't work for vegans. Check the labels of your products before you buy to ensure they don't contain butter or margarine. Butter is made by separating cream from whole milk. The cream is then churned until it thickens.  Some nutritionists claim that butters are the least harmful form of dairy to those with dairy allergies or lactose processing problems. Most people who face these issues have problems with the proteins found in milk. Since butter is 80 to 82 percent fat and contains relatively little protein, it doesn't tend to bother patients with dairy problems. For vegans, there are many margarines made without any cow byproducts. Check the label to make sure they don't contain whey, casein, or lactose. Cheeses in all forms constitute dairy. Obviously, you'll want to skip sliced cheeses on your sandwiches. Main dishes like pizza, burritos, tacos, and casseroles have cheeses in them. Don't eat cheese-based chip dips either. If you're at a restaurant, make sure that you ask if their dishes include cheese. Aged cheeses normally contain less lactose, while soft and hyper-processed cheeses contain higher levels. Cheese spreads are high in lactose as well. Most pastries are made with milk. Sadly this includes cakes, muffins, and doughnuts unless made with soy, rice, or hemp. Some breads are made with mono and diglycerides or lecithin — both of which are vegan and include no milk additives. Generally, these bread products will be labeled as vegan.

Summary:
Read labels on your food purchases. Avoid milk- and cream-based foods. Get rid of butter and most margarines that contain whey, casein, or lactose. Don't eat cheeses. Be wary of baked items.