Doctors have an expression that they use: "dose dependent." This means that people will sometimes not have side effects to a certain medication or substance until they eat more than a certain amount. The side effects are "dependent" on the "dose."
This is true for many people who have trouble with eating foods that contain lactose. Some can have 1/4 cup of milk on their cereal and not have problems but will experience symptoms if they drink a full glass of milk. Other people will have problems with as little as two tablespoons. Many people who cannot tolerate fresh milk can eat milk that has been cultured—like sour cream, yogurt and cheese—but, again, there are those who have problems with even these.
The recipes on my site have been placed into three categories: Lactose Free, Cheese-Containing Recipes, and Borderline Recipes. The Borderline category has dishes that have some milk but may not be a problem because there's only a little milk or dairy products. Some people may be able to tolerate these and others not. Unfortunately, for most people with lactose intolerance, trial and error is the only way to know for sure just how much dairy will cause a problem.
Recipe Categories: Lactose Free (this page) | Borderline | Cheese-Containing