Lactose-free describes foods with lactose removed, broken down, or reduced to the level allowed for that label. Lactose is the sugar naturally present in milk. In lactose-free dairy products, the enzyme lactase is often used to break it into simpler sugars.
Lactose-free milk and other dairy products may help people with lactose intolerance reduce symptoms while continuing to use dairy in cooking and everyday meals. Individual tolerance varies. Lactose-free milk can taste sweeter than regular milk because its sugars have been broken down.
Lactose-free is not the same as dairy-free. Lactose-free cow's milk still contains milk proteins and is not suitable for someone with a cow's milk protein allergy. Check the ingredients and allergen labeling rather than relying on a lactose-free claim.
See ASCIA's explanation of lactose intolerance and milk allergy.