Lactose Intolerance Symptoms

Quick Glance: Common Lactose Intolerance Symptoms

The most common lactose intolerance symptoms are digestive and usually develop within a few hours of consuming milk or other lactose-containing foods. These symptoms include:

• Bloating or a swollen feeling in the abdomen

• Abdominal pain or stomach cramps

• Excessive gas or flatulence

• Diarrhoea or loose stools

• Nausea

• Stomach rumbling or growling sounds

• Vomiting, in some people

• A feeling of abdominal discomfort after consuming dairy products

Symptoms of Lactose Intolerance That Should Not Be Ignored

Lactose intolerance itself is generally not considered a serious condition. However, persistent or unusual symptoms should be medically evaluated because they may indicate dehydration, nutritional problems, another digestive disorder or a milk allergy rather than lactose intolerance alone. Some of these symptoms include:

Why Do Lactose Intolerance Symptoms Occur?

Lactose intolerance symptoms occur when the small intestine does not produce enough of the digestive enzyme lactase to break down all the lactose consumed in food or drinks. Normally, lactase breaks lactose, the natural sugar in milk, into two simpler sugars called glucose and galactose. These sugars can then be absorbed through the lining of the small intestine.

When there is not enough lactase, some lactose remains undigested and passes into the large intestine (colon). Gut bacteria ferment the undigested lactose, producing gases that can lead to bloating, flatulence and abdominal rumbling. The presence of unabsorbed lactose can also draw water into the bowel, contributing to loose stools or diarrhoea.

The amount of lactose consumed also affects symptoms. A person may tolerate a small amount of dairy but develop symptoms after consuming a larger quantity. The timing and severity of symptoms can therefore vary considerably from one person to another.

Symptoms of Lactose Intolerance That Require Immediate Medical Attention

Take urgent medical attention if lactose intolerance symptoms suggest severe dehydration, a serious gastrointestinal problem or a possible allergic reaction. The symptoms that require immediate medical attention are:

• Difficulty breathing, wheezing or throat tightness after consuming milk or dairy products

• Swelling of the lips, tongue, face or throat

• Fainting, severe dizziness or confusion may occur with significant dehydration or a severe allergic reaction.

• Persistent vomiting or severe diarrhoea

• Blood in the stool or black, tarry stools

• Severe or persistent abdominal pain

• Signs of severe dehydration, such as very little urine, extreme weakness or marked dizziness

Symptoms of Lactose Intolerance Based on Type

Primary lactose intolerance is the most common form and occurs when lactase production naturally decreases with age. Secondary lactose intolerance can occur when an illness, infection or condition damages the small intestine. Congenital lactase deficiency is rare and is present from birth.

The various symptoms of lactose intolerance based on types are given in the table below:

Symptoms of Lactose Intolerance in Children

The common lactose intolerance symptoms children may experience are as follows:

• Diarrhoea

• Poor weight gain

• Irritability

• Abdominal bloating

• Failure to thrive (particularly in infants with congenital lactase deficiency)

Can You Have Lactose Intolerance Without Symptoms?

Yes. A person may have lactose malabsorption without experiencing noticeable symptoms. Lactose malabsorption means the body does not fully digest or absorb lactose, but symptoms may not occur unless enough lactose is consumed to exceed the individual's tolerance level.

Some people can digest small amounts of lactose without discomfort but develop symptoms after consuming larger quantities. So, the severity of symptoms can vary between individuals.

It is also possible for digestive symptoms to be caused by conditions other than lactose intolerance. For this reason, recurring symptoms should be discussed with a healthcare professional rather than diagnosed through symptoms alone.

When Can Lactose Intolerance Symptoms Become Life-Threatening?

The table below explains when lactose intolerance symptoms can become life-threatening:

How are Lactose Intolerance Symptoms Diagnosed?

A healthcare professional may evaluate the pattern of symptoms, dietary history, and medical history before deciding whether testing is needed to diagnose lactose intolerance. The various diagnostic tests used to diagnose lactose intolerance are given below: