Lactose Intolerance Symptoms

People with Lactose Intolerance are deficient in lactase, a substance produced in the small intestine that helps in the digestion of lactose. Due to this deficiency, patients with lactose intolerance are incapable of digesting products with lactose such as milk

lactose intolerance symptoms

People with Lactose Intolerance are deficient in lactase, a substance produced in the small intestine that helps in the digestion of lactose. Due to this deficiency, patients with lactose intolerance are incapable of digesting products with lactose such as milk. This can trigger a number of symptoms in patients. While lactose intolerance, sometimes called lactose malabsorption, is not really life-threatening. The resulting symptoms may cause discomfort and inconvenience to the patient or individual. Some individuals who are lactose deficient or those with minor lactose deficiency can still consume and digest dairy products. However, those who are really lactose deficient and intolerant may have to avoid consuming or ingesting any form of dairy product.

Signs and Symptoms of Lactose Intolerance

Lactose is a form of naturally occurring sugar found in animal-based food items such as milk and dairy. As stated earlier, lactose intolerance occurs when the body does not have enough lactase to process products with lactose that either consumed or ingested by an individual. This inability to properly process or digest lactose or lactose intolerance can lead to a number of possible symptoms. Listed below are some the said signs and symptoms of lactose intolerance:

Bloating of and Pain in the Stomach

Bloating of and pain in the stomach for both children and adults are common signs and symptoms of lactose intolerance. If left undigested, lactose can pass through an individual’s stomach or gut and into his/her colon. In the colon, the undigested lactose will be processed by bacteria present in the colon known as microflora. This processing or fermentation of the undigested lactose will result in the production of short chain fatty acids, and the release of various gases such as carbon dioxide, methane and hydrogen.

The resulting production of various gases and the elevated levels of acids usually lead to pain and cramps of the stomach. Individuals will most often feel pain around the lower half of the tummy and the navel. Bloating, on the other hand, is a sensation brought about by distention or the swelling of the gut and stomach. This is due to increased levels of water and gas. It may be noteworthy to mention that the amount of pain or bloating the individual experiences is not directly proportional to the amount of lactose ingested or consumed. Rather, it is based more on how sensitive an individual’s gut or stomach is to lactose.

A healthcare professional or physician may also look at other factors that may be contributing to a patient’s bloated sensation and stomach pain. Factors may include nutrient malabsorption, overeating, infections, other ailments, and other contraindicated medications.


It has been defined as the increased liquidity of stool, it’s frequency and volume of passing. Passing stool that is more than 7 ounces or around 200 grams is officially classified as having diarrhea. The excess water caused by lactose intolerance also increases the water in the stool increasing its volume and liquidity.

This kind of diarrhea caused by lactose intolerance is more common in babies and young children. The increase of water in the stool is also caused by microflora fermented lactose in the colon as the leftover lactose and fatty acids contribute to the overall liquidity of the stool. Lactose is not the only culprit though, in terms of causing diarrhea in patients.

Other factors will also be determined by a healthcare professional or doctor in determining the cause of a patient’s diarrhea. It could be other contraindicated medications, the patient’s diet, nutritional malabsorption, other ailments and inflammatory conditions of the bowels.

Increased Gas

As stated earlier, the processing of lactose in the colon by microflora produces carbon dioxide, methane, and hydrogen. This increases the production of gas in an individual’s colon. It has even been observed that individual’s with lactose intolerance usually have microflora in their bowels. It is very active and efficient in fermenting undigested lactose thereby increasing the production of gas and flatulence.

Note that gas production varies per individual. It depends on the actual diet, microflora, and the colon’s gas reabsorption capability. Interestingly, gas resulting from the fermentation of lactose have no odor compared to gas produced by protein breakdown.


Patients with lactose intolerance may experience constipation. Constipation is described as individuals experiencing hard passing of stool, infrequent passing of stool, the sensation of having an incomplete passing of stool, straining while passing stool and a bloated sensation. The fermentation of lactose in the colon produces methane gas which has been identified as the possible reason for the slow down in the digestion of food. This slow down in food digestion is the primary cause of patient constipation. It is worth noting though that constipation symptoms have only been closely studied in patients with IBS or irritable bowel syndrome and an overgrowth of bacteria. So, further studies may have to conducted for patients with lactose intolerance. Physicians will always check for other causes of constipation such as lack of fiber in a patient’s diet, dehydration, contraindicated medications, hemorrhoids, Parkinson’s disease, hypothyroidism and as mentioned earlier, irritable bowel symptoms.

Other Symptoms

Lactose intolerance can also have other symptoms that can cause patients significant discomfort. Most symptoms are typically centered around the gastrointestinal system of the patient but may include others such as eczema, loss of concentration, fatigue, joint pain, muscle pain, headaches, mouth ulcers, and problems urinating. Patients with milk allergy may suspect lactose intolerance symptoms. They may occur at the same time, making it harder to differentiate from each other and diagnose separately. Milk allergy and lactose intolerance are different from each other. Milk allergy symptoms include anaphylaxis, asthma, rash, eczema, diarrhea, vomiting, and stomach pain.

What can patients do if they notice lactose intolerance symptoms?

Patients should immediately seek medical attention if they think they have symptoms of lactose intolerance. A simple hydrogen breath test can determine if an individual has lactose intolerance or not. This is particularly important as milk allergy. It has similar symptoms as that of lactose intolerance and is considered a life-threatening medical condition.

lactose intolerance symptoms

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