General Practice 2022

How to know if I have an intoleranceâance à lactose (with online test)

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How to know if I have an intoleranceâance à lactose (with online test)
How to know if I have an intoleranceâance à lactose (with online test)

To confirm the presence of lactose intolerance, it is important to consult a gastroenterologist, to evaluate the symptoms and perform tests such as breath test, stool examination and/or bowel biopsy.

Lactose intolerance is the body's inability to digest the sugar present in milk, lactose, causing symptoms such as colic, gas and diarrhea, which appear a few moments after eating foods with lactose.

Although it is usually diagnosed in childhood, lactose intolerance can also develop in adulthood, with more or less intense symptoms depending on the severity of the intolerance. See a more complete list of symptoms of lactose intolerance.

1. Watch for symptoms of lactose intolerance

Lactose intolerance usually causes symptoms such as abdominal bloating, poor digestion, diarrhea and gas, which appear shortly after eating foods with lactose, such as milk, yogurt or butter, for example.

If you think you may have lactose intolerance, select your symptoms in this online test to find out your risk:

  1. 1.Swollen belly, abdominal pain or excess gas after consuming milk, yogurt or cheese Yes No
  2. 2.Alternating periods of diarrhea or constipation Yes No
  3. 3.Lack of energy and excessive tiredness Yes No
  4. 4.Easy irritability Yes No
  5. 5.Frequent headache mainly after meals Yes No
  6. 6.Red spots on the skin that can itch Yes No
  7. 7.Constant pain in muscles or joints Yes No


Make an appointment with a specialist

Symptoms can also manifest with more or less intensity according to the degree of inability to produce lactase, which is the enzyme that digests cow's milk.

2. Take a food exclusion test

If you suspect you may be lactose intolerant, a good strategy is to stop consuming milk and dairy products for a period of 7 days.

If after this period, you no longer have symptoms, drink some milk again and observe your body's reaction. If symptoms return, it is possible that it is, in fact, lactose intolerance.

See how to follow a lactose-free diet.

3. Go to the doctor and get tested

To be sure that you are lactose intolerant, the ideal is to consult a gastroenterologist, who will evaluate the symptoms and ask for tests such as:

  • Stool Examination: Measures stool acidity and is very common for detecting lactose intolerance in infants and young children.
  • Exhaled air test: measures the abnormal presence of hydrogen in expired air after ingestion of lactose diluted in water.
  • Blood test: measures the amount of glucose in the blood after taking lactose diluted in water in the laboratory.
  • Intestinal biopsy: in this case a small sample of the intestine is analyzed under a microscope to identify the presence or absence of specific cells that determine lactose intolerance. Despite being very useful, it is less used because it is more invasive.

These tests may be requested by the general practitioner or allergist in case of suspicion of lactose intolerance or when the food exclusion test leaves some doubts. See the main tests used to diagnose lactose intolerance.

It is very important to diagnose lactose intolerance to adapt the diet and avoid unpleasant symptoms, in addition to improving the absorption of nutrients in the intestine. Understand how the diet for lactose intolerance should be.

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