To test for lactose intolerance at home, keep a food journal of your dairy consumption, suggests Mayo Clinic. In your journal, record how many servings of dairy you have, the specific type of dairy product you consume, what time you eat it and what foods you ate with the dairy product. Then write down any subsequent symptoms of lactose intolerance that occur. You can also completely eliminate dairy for a few days to find out if your symptoms ease.
Take your food journal with you to visit your doctor to confirm lactose intolerance, states Mayo Clinic. A doctor can confirm your suspicions by ordering a lactose tolerance blood test or a hydrogen breath test. Doctors may test young children and infants for lactose intolerance using a stool acidity test.
Common symptoms of lactose intolerance include bloating, gas, loose stools or diarrhea, according to WebMD. People who can't digest dairy products may also vomit, experience pain or cramping in their abdomen, or hear rumbling sounds from the belly. Infants who are lactose intolerant have symptoms such as foamy diarrhea, diaper rash, irritability, vomiting and dehydration.
Do not confuse lactose intolerance for a food allergy to milk, which causes severe symptoms and requires sufferers to avoid all milk products, notes WebMD. Lactose intolerance symptoms are also similar to symptoms caused by digestive upset resulting from fructose or sorbitol consumption, irritable bowel syndrome, excessive use of laxatives and inflammatory bowel disease, so an official diagnosis is important.