How long does it take to pass lactose?

In this brief study, we will answer the question, “how long does it take to pass lactose?” and will also talk about lactose intolerance in detail.

How long does it take to pass lactose?

Lactose will take approximately two hours to digest to the ones who are lactose tolerant.

In the case of lactose intolerance, it typically takes 30 minutes to 2 hours after eating dairy for lactose intolerance symptoms to emerge, and they should disappear after the dairy has passed through your digestive system entirely, which takes about 48 hours.

What is lactose intolerance?

Lactose is a kind of sugar that may be found in dairy products. A protein is known as Lactase aids in the digestion of this substance. It is the cells of the small intestine that produce lactase, therefore when the body does not produce enough lactase, it results in the body being unable to effectively break down lactose.

How long do the symptoms of lactose intolerance last?

The intensity of your symptoms will vary depending on how much lactose you eat and how much lactase your body generates in response to that consumption.

It is expected that symptoms of lactose intolerance would subside within 48 hours, if not sooner. For as long as lactose is present in your digestive tract, you will experience the following symptoms:

  • Bloating is caused by water and gas that has been trapped in the intestines. Bloating discomfort around the belly button is a common complaint among people.
  • It is possible to feel nausea within two hours after consuming dairy products if you are lactose intolerant.
  • Diarrhea is a frequent complaint among people. Lack of digestion results in fermentation in the stomach, which leads to water retention and dehydration.
  • The fermentation of lactose in the stomach may result in the buildup of hydrogen, methane, and carbon dioxide in the stomach.
  • The stomach pain experienced by those suffering from lactose intolerance is common. Trapped gas pushes on the walls of the intestines, which causes pain in most cases.

Testing for lactose intolerance

The results of a lactose tolerance test are determined by a doctor taking blood samples and checking your fasting glucose levels. Following that, you will have a lactose-containing beverage. In the next few hours, the doctor will compare your blood glucose levels to those measured at the beginning of the visit.

You may be lactose intolerant if your glucose levels remain normal, which indicates that your body is unable to break down lactose into separate sugars, indicating that you are not lactose intolerant.

Test for hydrogen in the breath

During the hydrogen breath test, you will be given a beverage that has a high amount of lactose. The quantity of hydrogen in your breath will then be determined by a medical professional.

Those who are lactose intolerant will notice that their breathing becomes more hydrogenated as a result of the lactose fermenting in their stomachs.

Test for acidity in the feces

The stool acidity test is usually reserved for children who are unable to be evaluated using other techniques. The acidity of a stool sample is measured to determine whether or not there is undigested lactose present in the form of lactic acid.

Types of Lactose Intolerance

Lactose intolerance may be classified into three categories. Lactase insufficiency is caused by a variety of causes that are not all related.

Primary lactose intolerance

Individuals with primary lactose intolerance, which is the most common kind, are born with insufficient lactase enzyme production. Lactase is required for infants that get all of their nourishment from their mother’s breast milk.

When children substitute other foods for milk, their lactase production often decreases, but it still produces enough enzymes to digest the quantity of dairy seen in a typical adult diet. Adults with primary lactose intolerance have much lower lactase production than the general population, which makes milk products more difficult to digest.

Secondary lactose intolerance

Due to the injury, or surgery that damages the small intestine, this kind of lactose intolerance may develop. It has been shown that intestinal infection, celiac disease, bacterial overgrowth, and Crohn’s disease are all associated with secondary lactose intolerance.

Treatment for the underlying disease may be able to restore lactase levels and alleviate symptoms, but this may take some time to occur.

Congenital or developmental lactose intolerance

When the enzyme lactase is absent from the body, infants can be born with lactose intolerance. However, this is very uncommon. This disease is inherited in an autosomal recessive manner, which means that both the mother and father must pass on the same gene variation for a child to be afflicted. Lactose intolerance may occur in preterm babies as a result of a deficiency in the enzyme lactase.


In this brief study, we answered the question, “how long does it take to pass lactose?” and also talked about lactose intolerance in detail.


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