Can You Suddenly Become Lactose Intolerant?

Medically Reviewed on 2/15/2022
lactose intolerance
People may become lactose intolerant at any point of time in their lives.

Yes, people may become lactose intolerant at any point of time in their lives even if they never had any difficulty digesting milk and its products before.

This sudden onset of lactose intolerance may be caused by various medical conditions that disrupt the health and functionality of the gut, which include:

One may even grow out of lactose intolerance with age.

What is lactose intolerance?

Lactose intolerance is a condition in which the body is unable to digest lactose, a type of natural sugar found in milk and dairy products. This is not the same as having a milk allergy.

  • Lactose that passes through the large intestine (colon) without being properly digested can result in unpleasant symptoms, such as gas, abdominal pain, and bloating.
  • Lactose intolerance prevents one from digesting milk products. Others can consume modest amounts of milk products or specific types of milk products without any problem.

All adults are prone to lactose intolerance; however, it is more common among Native Americans, Asian, African, and South American descendants than in European descendants.

Learning how to eat to avoid discomfort and receive enough calcium for good bones is a major difficulty for lactose-intolerant persons.

It may be difficult for lactose-intolerant people to consume enough calcium. Calcium supplements, such as calcium carbonate, are frequently prescribed. The choice to use calcium supplements should be reviewed with the doctor.

What are the signs and symptoms of lactose intolerance?

As undigested lactose reaches the intestine, the intestinal bacteria break it down to produce:

These substances may produce various symptoms, such as:

These symptoms typically appear 30 minutes to 2 hours after consuming lactose-containing foods. The degree of symptoms is usually determined by the amount of lactose consumed and the amount of the enzyme lactase that remains in the intestine.

Risk factors of lactose intolerance

  • Premature birth: Cells that produce the enzyme lactase are not developed until the late third trimester
  • Older age
  • Ethnicity: African American, Hispanic, American, Indian
  • Diseases that disrupt the integrity and functionality of the intestine, such as long-standing infections
  • Lactose intolerance may be developed following treatments for various cancers


Allergies can best be described as: See Answer

How is lactose intolerance diagnosed?

A thorough medical history will be taken by the doctor to make the diagnosis, who may also order various tests to confirm lactose intolerance.

Laboratory tests

  • Breath hydrogen test: Hydrogen gas is produced in the gut when lactose is broken down by bacteria in the intestine. This gas is removed from the body through the expiration process of the lungs. The intake of lactose produces a significant amount of hydrogen in the body. If a breath test indicates the presence of hydrogen gas, the test is positive for lactose intolerance.
  • Lactose tolerant test: The blood sugar levels rise significantly after consuming a lactose meal in lactose-intolerant patients. Patients are asked to have a lactose meal a few hours before the test that measures blood glucose levels. To digest the lactose load ingested, the amount of the enzyme, lactase, increases. Because lactase increases, the blood sugar levels increase. If a person is not lactose intolerant, their blood sugar levels appear normal.
  • Fecal pH test: Lactose is broken down into lactic and other acids in the colon, and the resulting acidity can be measured using a simple stool acidity test. This exam is typically designated for infants or tiny children who are unable to do the other tests.


First, abstain from milk and lactose-containing foods for a few days. Then, consume two large glasses of skim or low-fat milk. If symptoms appear within four hours, lactose intolerance is almost definite.

How to treat lactose intolerance

The treatment for lactose intolerance depends on the willingness to accept the symptoms. If the symptoms are minor, avoiding large quantities of milk and milk products may be sufficient.

Some may be extremely sensitive to little levels of lactose, which can be treated in two ways:

  1. First option:
    • To begin, all foods should be thoroughly tested for lactose
    • Bread, baked goods, cereals, instant potatoes, soups, margarine, lunch meat, salad dressings, pancakes, biscuits, cookies, and sweets can have lactose hidden in them
    • Lactose can be found in both prescription and over-the-counter medications; read labels to avoid foods that have milk and lactose on their labels
  2. Second option:
    • Purchase lactose-free milk substitutes that are widely available in most grocery shops
    • Consume milk that readily contains the enzyme lactase
    • Lactase drops or tablets are available as over-the-counter medications
    • These can be mixed with milk or can be taken with meals to replace the enzyme that the body no longer has

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Medically Reviewed on 2/15/2022
Image Source: iStock Images

Nabili SN. Lactose Intolerance. eMedicineHealth.

National Institutes of Health. Lactose Intolerance.

Cleveland Clinic. Lactose Intolerance.