[raybbr]

People who do not have enough lactase to digest the amount of lactose they consume may feel very uncomfortable when they digest milk products. Common symptoms, which range from mild to severe, include nausea, cramps, bloating, gas, and diarrhea. Symptoms begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. The severity of symptoms depends on many factors, including the amount of lactose a person can tolerate and a person’s age, ethnicity, and digestion rate.

"Symptons begin..." That doesn't mean diarrhea in 30 minute. Still you would have to clear any food already present. In an extreme case? Maybe. I know from personal experience that it takes about four hours for the diarrhea to kick in. :(

[aft_lizard]

Really not trying to argue but I will tell you that you will get gas and diarrhea that fast, I am a lactose intolerant individual and give me anything that is heavy with lactose and I am clearing rooms and destroying toilets within the hour. I can’t find my old physiology books but lactose intolerance is one of many conditions that will give you fast bowel movements.