What happens if you ignore lactose intolerance?

Are you worried about the long-term effects of consuming dairy products if you’re lactose intolerant? While lactose intolerance can cause a lot of abdominal discomfort and distress, it is not usually harmful. Lactose intolerance is caused by a deficiency in lactase, a crucial enzyme in the digestive tract, which is needed to fully break down a type of sugar in milk (lactose).

When lactose is unable to be broken down and absorbed in the small intestine, it passes undigested into the large intestine, where it interacts with gut bacteria. These bacteria can then break down the lactose, but they also end up producing fatty acids and gases, such as carbon dioxide, hydrogen and methane in the process. These bacterial byproducts lead to nausea, vomiting, stomach cramps, bloating, flatulence and diarrhea.

If you have lactose intolerance and do not limit your consumption of foods containing lactose, you can develop chronic diarrhea. Chronic diarrhea can lead to dehydration, electrolyte imbalances and malabsorption of essential nutrients. However, most people can eat a small amount of dairy or other lactose-containing foods without experiencing symptoms. People often find that other dairy products, such as yogurt and cheeses, are easier to digest than milk. 

To confirm whether you have lactose intolerance, as opposed to another condition such as a milk allergy or other digestive condition, you should see your healthcare provider. You can ask them questions about any testing, your intake of dairy products, or possibly seeing a dietitian to ensure you're getting all the key nutrients that your body needs. If you are lactose intolerant, your provider may suggest taking lactose intolerance supplements.

Updated by Amy Magill, MA, RDN, September 2024.