Drinking milk can give your system fits, everything from gas to nausea to diarrhea. But that doesn’t mean you’re allergic to dairy.

While the symptoms may seem like a typical food allergy, nine times out of 10, it’s merely a sensitivity. You may think, ‘Easy for them to say,’ but there really is a scientific difference between an allergy and an intolerance.

True food allergies are serious, and in extreme cases, can be fatal. Food allergens, which cause allergic reactions, are usually proteins. Research indicates that cow’s milk protein is one of the most common allergens, but even so, that accounts for just 2.5 percent of food allergies in children and 1 percent in American adults.

With a true allergy, the body’s immune system attacks itself, inducing symptoms such as asthma, sinusitis, eczema and gastrointestinal distress, as well as bleeding, pneumonia and anaphylaxis (shock).

So what about everyone else who has discomfort from abdominal pain to vomiting when they consume milk or its by-products? That’s lactose intolerance, and it means your body lacks the enzyme to break down the sugars found in milk, not the proteins. It also means you can eat certain dairy items, like yogurt, but not others.

The only way to tell whether you’re truly allergic or just intolerant is to have a blood test.