Skip to main content
Mother Nature AI
DigestiveICD-10: E73Affects approximately 36% of Americans and 68% of the world's population

Lactose Intolerance

Also known as: Lactase Deficiency, Dairy Intolerance

Lactose intolerance is a common digestive condition in which the body cannot fully digest lactose, the sugar in milk and dairy, due to lactase enzyme deficiency. Undigested lactose causes gas, bloating, and diarrhea. It is distinct from milk allergy, which is an immune-mediated and potentially life-threatening condition.

Symptoms

Bloating and abdominal cramps
Diarrhea
Gas and flatulence
Nausea, sometimes with vomiting
Stomach rumbling or gurgling
Symptoms typically occur 30 minutes to 2 hours after dairy consumption

Causes

  • Primary lactase deficiency (genetically programmed decline after weaning — most common)
  • Secondary lactase deficiency from small intestine injury (celiac, Crohn's, gastroenteritis)
  • Congenital lactase deficiency (rare genetic condition)
  • Developmental lactase deficiency in premature infants

Risk Factors

  • African, Asian, Hispanic, and Native American descent
  • Increasing age
  • Premature birth
  • Diseases affecting the small intestine

Diagnosis

  • Hydrogen breath test (gold standard)
  • Lactose tolerance blood test
  • Elimination diet trial
  • Genetic testing for lactase persistence gene

Treatment

  • Dietary lactose reduction
  • Lactase enzyme supplements taken with dairy meals
  • Lactose-free dairy products
  • Calcium and vitamin D supplementation if dairy is significantly reduced
  • Gradual reintroduction to determine personal tolerance level

Prevention

  • Primary lactose intolerance cannot be prevented
  • Secondary forms may be prevented by treating underlying intestinal conditions
  • Lactase supplements can prevent symptoms before consuming dairy

When to See a Doctor

  • Digestive symptoms consistently occur after consuming dairy
  • You need help determining if symptoms are lactose intolerance or another condition
  • Concerned about calcium and vitamin D intake
  • A child has persistent diarrhea or poor growth related to dairy

Frequently Asked Questions

Related Conditions

Irritable Bowel Syndrome (IBS)

Digestive

Celiac Disease

Autoimmune

Crohn's Disease

Autoimmune

Food Poisoning

Infectious

Have questions about Lactose Intolerance?

Ask Mother Nature AI for personalized, evidence-based guidance.

Ask about Lactose Intolerance

Medical Disclaimer: This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.

Content reviewed against peer-reviewed medical literature and clinical guidelines. Read our editorial standards.