Fast-food meals contain common food allergy ingredients, but they don't tell you which ones.

There are a variety of different ingredients used in even the most simple fast-food products you purchase at your local drive-thru. So if you have food allergies, you may want to think twice before you visit the golden arches.

A sausage burrito at McDonald's contains more than 50 different ingredients, including milk, egg, wheat, corn syrup, and a range of chemicals and preservative agents. The hash browns are cooked with animal products and the bacon contains wheat and soy.

Some fast-food joints, like Jack in the Box, spell out the most common sources of food allergies and then mention that one or more of their products may contain the allergens, but they don't specify which ones. Just covering all their bases, we think. Our advice: order a diet cola.