What Foods Contain Lactose?
The most common foods that are high in lactose include dairy products such as milk, ice cream, and cheese. Lactose is also added to some foods, such as bread and baked goods, cereals, salad dressings, candies, and snacks.
Foods that contain whey, curds, milk by-products, dry milk solids, and nonfat dry milk also contain lactose.
Lactose is also present in about 20% of prescription medications, such as birth control pills (oral contraceptives), and about 6% of over-the-counter medications, such as some tablets for stomach acid and gas.
Source: http://www.webmd.com