A: Alisa – The most important thing is to read the ingredients. Labels can be misleading, so always check the ingredient list for the potential allergen. Also, if your son’s allergy is severe, and potential cross-contamination is a concern, contact the company to confirm ingredients and manufacturing processes prior to consumption, even if it appears to be dairy-ingredient-free and even if it is labeled as “dairy-free” or “casein-free.”
But in direct response to your question on the labeling, the term dairy-free indicates that there are no dairy ingredients (see this article where I address the terms ‘non-dairy’ vs ‘dairy-free’), this would include lactose, casein, whey, etc.
Casein is a type of protein within milk. In other words, it is a component of dairy foods. Thus, a product can actually be casein-free, but contain another dairy “component” such as lactose or even dairy fat. Ghee for example is often labeled as casein-free. It is dairy butter, essentially. But it has been purified to, in theory, extract all of the proteins, leaving just pure butter fat. It is still a dairy product, but according to some manufacturers, it no longer contains casein. Whether or not such a food is safe for your son is something you should discuss with his physician as traces of the milk protein could still remain.
Manufacturers egg on the confusion by putting both “dairy-free” and “casein-free” on a single package. I hate that they do this as it implies that a dairy-free product may not be casein-free. In general (but as mentioned, always verify the ingredients!), dairy-free = casein-free but casein-free ≠ dairy-free.
Alisa Fleming is the founder of GoDairyFree.org and author of Go Dairy Free: The Guide and Cookbook for Milk Allergies, Lactose Intolerance, and Casein-Free Living. In addition to her own dairy-free lifestyle, Alisa has experience in catering to the needs of various special diets, including gluten-free, soy-free, egg-free, vegan, and multiple food allergies.