Duration of symptoms
How long the symptoms of lactose intolerance last after the intake of lactose varies greatly. It depends on how much activity the lactose-cleaving enzyme lactase still has and how much milk sugar has been ingested. The symptoms usually occur minutes to hours after the intake of lactose. The acute symptoms with diarrhea and abdominal pain usually last for several hours. However, many of those affected describe that they still suffer from a bloated stomach, flatulence and abdominal pain over the next few days.
Diarrhea
Diarrhea is one of the main symptoms of lactose intolerance. In healthy people, lactose is already metabolized in the small intestine by the enzyme lactase and then absorbed through the intestinal wall. If there is not enough lactase, the milk sugar reaches the large intestine.
Here numerous intestinal bacteria that belong to the natural intestinal flora sit. They decompose the lactose, thereby gases develop by fermentation processes. These lead to strong Blähungen and stomach pain.
In addition the still unsplit lactose in the large intestine attracts much water. If a lot of water gets into the large intestine, this leads to a liquefaction of the stool produced there. This leads to a significant acceleration of the intestinal passage. This leads to sudden severe diarrhea.
Constipation
Constipation symptoms do not actually occur in the context of lactose intolerance. On the contrary. Because the lack of metabolism of milk sugar causes diarrhea in many sufferers a short time after the intake of milk sugar.
Flatulence and bloating
Flatulence is a common symptom of lactose intolerance. As described above, they are caused by the fact that the lactose that cannot be sufficiently broken down reaches the large intestine where it is decomposed by intestinal bacteria. This produces gases such as carbon dioxide and methane. These gases accumulate in the intestine and provide so for Blähungen and stomach pain.
Heartburn
Heartburn is not a typical symptom of lactose intolerance. However, both lactose intolerance and heartburn are two things that occur relatively frequently in the population. Therefore, some people may suffer from lactose intolerance and have heartburn from time to time.Heartburn is caused by a backflow of stomach acid into the esophagus and has nothing to do with lactose.