Lactose Intolerance Symptoms, Causes, Treatment

Lactose Intolerance Symptoms, Causes, Treatment

Lactose intolerance is a condition that affects people who have difficulty digesting lactose, a sugar found in milk and dairy products. 

The body needs lactase, an enzyme produced in the small intestine, to break down lactose into two simpler sugars, glucose and galactose, absorbed into the bloodstream. 

Read on to learn more about lactose intolerance.

Types of Lactose Intolerance

There are three types of lactose intolerance: primary, secondary, and congenital or developmental. 

  • Primary lactose intolerance is the most common type. It is caused by a lack of lactase, which breaks down lactose into glucose and galactose. Lactase is produced in the small intestine and cannot be digested. Symptoms include bloating, gas, abdominal pain, diarrhea, and nausea. 
  • Secondary lactose intolerance is usually caused by an injury or illness that damages the small intestine and reduces the amount of lactase produced. Symptoms are similar to those of primary lactose intolerance. 
  • Congenital or developmental lactose intolerance. It is a rare condition that is present from birth.

Symptoms of Lactose Intolerance

Lactose intolerance is caused by a lack of the enzyme lactase, which is needed to break down lactose. When lactose isn’t broken down, it can cause uncomfortable symptoms like:

Symptoms of lactose intolerance usually develop within 30 minutes to two hours after eating or drinking something that contains lactose.

Causes of Lactose Intolerance

Lactose intolerance occurs when the small intestine does not produce enough lactase, which breaks down lactose into glucose and galactose. This leads to the lactose passing into the bloodstream undigested, then absorbed by the colon.

The bacteria in the colon ferment the lactose, causing symptoms such as bloating, gas, and diarrhea.

Lactose intolerance is unusual in infants and young children but apparent in adults who cannot produce lactase in the small intestine.

Risk Factors for Lactose Intolerance

Several factors can lead to lactose intolerance, including

  • Age: Age is a significant risk factor, as the body’s ability to break down lactose decreases with age.
  • Damage to the small intestine: Damage to the small intestine results from diseases like Crohn’s and celiac diseases.
  • Premature birth: Because lactase-producing cells do not develop until late in the third trimester in the small intestine, infants born prematurely might have reduced lactase levels.
  • Ethnicity: People of Asian or African descent are more likely to be intolerant to lactose. According to research, about 80% of African Americans may be lactose intolerant.
  • Cancer treatments: Certain cancer treatments, such as radiation therapy or chemotherapy, can damage the small intestine and lead to lactose intolerance.

Diagnosis for Lactose Intolerance

The first step in diagnosing lactose intolerance is typically a hydrogen breath test. In this test, you will be asked to drink a beverage that contains lactose and then breathe into a machine.

The machine will measure the amount of hydrogen in your breath, and if it increases after drinking the lactose beverage, you may be diagnosed with lactose intolerance.

Another standard test used to diagnose lactose intolerance is the lactose tolerance test. This test involves drinking a beverage that contains lactose and then having your blood sugar levels measured.

Treatment for Lactose Intolerance

Lactose intolerance caused by an underlying condition can be treated, but this process can take months. Alternatively, you could follow a low-lactose diet to avoid lactose intolerance discomfort.

Reduce your intake of lactose by:

  • Limiting dairy products such as milk and cheese
  • Regularly eating dairy products in small portions
  • Drinking lactose-free ice cream and milk
  • Breaking down lactose in milk with a liquid or powder lactase enzyme

Lifestyle Changes and Home Remedies

If you’re lactose intolerant, you may be able to ease your symptoms by making some changes to your diet. Here are a few tips:

  • Avoid dairy products, especially milk and cheese.
  • Eat plenty of calcium-rich foods, such as broccoli, kale, and fortified foods like orange juice and soy milk.
  • Take a vitamin D supplement, as vitamin D helps the body absorb calcium.
  • Drink lactose-free milk or use lactase pills or drops to help break down the lactose in dairy products.


Lactose intolerance is a widespread condition that can cause uncomfortable symptoms. 

It is important to seek diagnosis and treatment from a healthcare professional if you suspect you have lactose intolerance. 

There are various ways to manage the condition, and most people can find relief from their symptoms by making simple dietary changes.