What symptoms are commonly associated with lactose intolerance?

Lactose intolerance leads to a variety of gastrointestinal symptoms due to the body's inability to digest lactose, the sugar found in milk and dairy products. When individuals with lactose intolerance consume these products, the undigested lactose ferments in the colon, leading to symptoms such as gas and bloating. This fermentation process produces gases like hydrogen, methane, and carbon dioxide, which result in the sensation of bloating as well as abdominal pain.

Additionally, lactose intolerance can cause diarrhea. This occurs because the excess undigested lactose draws water into the intestines, leading to watery stools. Collectively, these symptoms—gas, bloating, and diarrhea—are hallmark signs of lactose intolerance and occur relatively quickly after the consumption of lactose-containing foods.

Other options do not accurately reflect the common symptoms experienced with lactose intolerance. For instance, headaches and fatigue can be associated with various other conditions but are not primary symptoms of lactose intolerance, while nausea and dizziness may occur in some individuals but are less directly linked. Weight gain and increased appetite are also unrelated to lactose intolerance and instead might be influenced by different dietary choices or metabolic conditions.