Not being able to fully digest sugar, called lactose, in dairy products.

Someone with lactose intolerance can't fully digest the milk sugar, called lactose, in dairy products. Lactose intolerance usually happens when the body doesn't have enough of an enzyme called lactase.

Symptoms can include belly cramps, bloating and diarrhea.

Staying away from dairy products or using products made for lactose-intolerant people can reduce symptoms.