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Lactose Intolerance
Mild
Lactose intolerance occurs when the small intestine does not produce enough lactase, the enzyme needed to digest lactose, the natural sugar in milk. Undigested lactose passes into the large intestine, where bacteria break it down and produce gas and other substances that can cause symptoms. Typical symptoms include bloating, abdominal discomfort, gas, and diarrhea after consuming lactose-containing foods. The severity varies between individuals and depends partly on the amount of lactose consumed and the degree of lactase deficiency.
Body System
Digestive System
When to Seek Medical Attention
Lactose intolerance is generally not an emergency. Seek medical assessment if symptoms are severe, persistent, unexplained, or associated with significant weight loss, blood in the stool, persistent vomiting, or another concerning change. Severe dehydration or significant bleeding requires urgent medical attention.
Symptoms
3
Causes
1
Treatments
5
Diet
4
Overview
Lactose intolerance occurs when the small intestine does not produce enough lactase, the enzyme needed to digest lactose, the natural sugar in milk. Undigested lactose passes into the large intestine, where bacteria break it down and produce gas and other substances that can cause symptoms. Typical symptoms include bloating, abdominal discomfort, gas, and diarrhea after consuming lactose-containing foods. The severity varies between individuals and depends partly on the amount of lactose consumed and the degree of lactase deficiency.
Symptoms 3
Diarrhea
Heartburn
Lower Abdominal Pain
Causes 1
The main cause of lactose intolerance is reduced production or activity of the lactase enzyme in the small intestine. Primary lactose intolerance develops when lactase production naturally decreases after childhood. Secondary lactose intolerance can occur when an intestinal disorder or injury damages the intestinal lining, temporarily reducing lactase activity. It may occur with certain gastrointestinal conditions or infections. Rarely, congenital or developmental problems can result in lactase deficiency from infancy.
Genetics
Risk Factors
Risk depends on the underlying type of lactose intolerance. Primary lactase reduction is common with increasing age in many populations. Secondary deficiency may occur after intestinal infections, inflammatory disorders, or other conditions that affect the small intestinal lining. Genetic background also influences lactase persistence into adulthood. The amount of lactose consumed, the food in which it occurs, and individual digestive tolerance affect whether symptoms develop.
Diagnosis
Diagnosis is based on a patient's medical history,
symptoms, physical examination and, when necessary,
laboratory or imaging investigations.
Diagnosis is based on the relationship between lactose consumption and digestive symptoms. A healthcare professional may review dietary history and may recommend a temporary reduction in lactose followed by controlled reintroduction. A hydrogen breath test can help confirm lactose malabsorption by measuring hydrogen produced after lactose is consumed. Other gastrointestinal conditions may cause similar symptoms, so persistent or severe digestive complaints may require evaluation for alternative diagnoses.
Prevention
Key Prevention Tips
Primary lactose intolerance related to genetically determined lactase reduction cannot generally be prevented
Secondary lactose intolerance may improve when the underlying intestinal condition is identified and treated
People who experience symptoms can often reduce discomfort by adjusting the amount and timing of lactose consumed rather than unnecessarily eliminating all dairy foods
Adequate calcium and vitamin D intake should be maintained through tolerated foods or appropriate alternatives, particularly when dairy consumption is reduced
Prevention Guidance
Primary lactose intolerance related to genetically determined lactase reduction cannot generally be prevented. Secondary lactose intolerance may improve when the underlying intestinal condition is identified and treated. People who experience symptoms can often reduce discomfort by adjusting the amount and timing of lactose consumed rather than unnecessarily eliminating all dairy foods. Adequate calcium and vitamin D intake should be maintained through tolerated foods or appropriate alternatives, particularly when dairy consumption is reduced.
Reminder: Prevention recommendations should be tailored to your personal health status and risk factors.
Treatment & Management 5
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Medical Note: The treatment information provided is intended for educational purposes only.
Always consult a qualified healthcare professional before starting,
stopping, or changing any treatment.
Diet & Nutrition 4
Recommended Foods
Lactose-Free Milk
Provides nutrition without symptoms.
Soy Milk
Alternative to dairy products.
Fresh Fruits
Naturally lactose free.
Vegetables
Support overall nutrition.
Foods to Avoid
Regular Milk
Contains lactose.
Ice Cream
May trigger symptoms.
Soft Cheese
May contain significant lactose.
Medical Nutrition Note: Diet recommendations are intended for general educational purposes and should be tailored to individual health needs by a qualified healthcare professional.
Frequently Asked Questions 5
It is the inability to digest lactose properly.
Bloating, gas, diarrhea, and abdominal pain may occur.
Dietary evaluation and lactose tests may be used.
Some people tolerate small amounts or lactose-free products.
Reducing lactose intake helps control symptoms.
Helpful Tip: These answers provide general medical information.
Consult your healthcare provider for advice tailored to your condition.