In this forum theree is a question originally about lactose intolerance later in the title changed to allergy.
The answers contain a lot of misconceptions about the problem, especially the most voted spreads misconceptions that on the long term can be damaging for people health. I tried and add some warning and explanations in comments, but the moderators intervened removing all the comments and leaving the question locked in a form that leaves a dangerous disinformation. Ignore the answers posted to this question.
Update: The absurdity of this story is that not only the moderators keep removing my warnings, but also the highly voted answers to this question repeat the same misconceptions. Sadly I note that such obtuse repetition can only be the result of a widespread disinformation.
First of all. There is not a fixed certain amount of lactose that a person with lactose intolerance can tolerate. Irritable Bowel Syndrome is very common among people with food intolerances and also temporary irritations can worsen the reaction to a wrong meal. The way poeple react to the food that causes the intolerance changes with the current medical conditions the assumption that a fixed amount can be tolerated often leads to underestimate the problem.
Second. When the medical conditions are bad a tiny amount of lactose can cause severe reactions. The distinction between allergy and intolerance is a dangerous assumption. Allergy conditions are rare and only after a tourough medical examination they can be determined. Someone who, without any knowledge of the condition of a person, tells them that they are probably allergic is abusing the medical profession in a grossly negligent manner.