Lactose intolerance is also more common among certain ethnic groups. From time to time, almost anyone may experience a temporary bout of lactose intolerance. This means that your body tends to produce only as much lactase as needed. Even those who produce normal levels of lactase will become deficient if they stop drinking milk for an extended period of time. When they start drinking milk again, they may experience symptoms of lactose intolerance until their body once again produces a sufficient quantity of lactase.
Several tests are available to help doctors diagnose lactose intolerance.
The latter test is especially useful in diagnosing lactose intolerance in infants. However, most people don't need a doctor's diagnosis to know they suffer from lactose intolerance. They know because of what happens every time they drink a glass or two of milk. The level of lactose intolerance is highly variable from person to person. Some people have symptoms after they drink or eat even small quantities of dairy products.