First your doctor will take your medical history to understand your symptoms and how your body reacts to dairy foods. Then you’ll be tested to confirm whether it’s lactose intolerance or a dairy allergy.
Testing for Lactose Intolerance
Most adults with probable lactose intolerance are never formally tested.
Lactose tolerance test: You’ll drink a liquid that contains a lot of lactose. About 2 hours later, the amount of glucose (sugar) in your blood stream will be measured. If your glucose level doesn’t rise, you’re not digesting the lactose in the drink.
Hydrogen breath test: You’ll drink a liquid that contains a lot of lactose. Then, the hydrogen in your breath will be measured at regular intervals. If you’re not digesting lactose, it will be broken down in your colon, releasing hydrogen that can be detected in your breath.
Stool acidity test: Babies and children who can’t be tested otherwise can have their stool tested for lactic acid caused by the breakdown of undigested lactose in the colon.
Testing for dairy Allergy
Skin prick test: A small drop of liquid containing the dairy allergen is placed under your skin on your forearm or back. If a raised bump surrounded by itchy red skin appears, a dairy allergy is likely.
Your doctor might have you take a blood test too, which measures the amount of certain antibodies in your blood.
Both tests can have “false positives.” You can test positive for an allergy even though you really don’t have it. Your allergist will explain the results.
If an allergy is still suspected but not confirmed, your doctor may have you take an oral challenge. You’ll be fed different foods that may or may not contain milk in increasing amounts to see if you react to food that contains milk.
Living with Lactose Intolerance
Lactose intolerance is easily managed, mostly by limiting the amount of dairy food and drink you consume. You can also try lactose-reduced ice cream and milk, or take lactase enzyme supplements when you eat dairy products to help your body digest lactose.
Living with Dairy Allergy
If you have a dairy allergy, you’ll need to avoid all dairy foods and other foods that contain dairy products.
Staying safe means reading food labels to see if milk or ingredients containing milk are included. Milk proteins are found in many foods you wouldn’t expect. Some canned tuna, energy drinks, and even chewing gum contain them. And don’t eat lactose-reduced foods if you have a dairy allergy. They still contain the milk proteins that can cause allergic reactions.
