Also called: Dairy product intolerance · Lactase deficiency · Milk intolerance
Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Lactose Intolerance
Lactose intolerance means that you cannot digest foods with lactose in them. Lactose is the sugar found in milk and foods made with milk. After eating foods with lactose in them, you may feel sick to your stomach. You may also have:
- Gas
- Diarrhea
- Swelling in your stomach
Your doctor may do a blood, breath or stool test to find out if your problems are due to lactose intolerance.
Lactose intolerance is not serious. Eating less food with lactose, or using pills or drops to help you digest lactose usually helps. You may need to take a calcium supplement if you don't get enough of it from your diet, since milk and foods made with milk are the most common source of calcium for most people.
It sits within Digestive System and Metabolic Problems.
The lead U.S. institute for this subject is the National Institute of Diabetes and Digestive and Kidney Diseases.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Lactose Intolerance
65 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- Partially Hydrolysed Whey Based Formula in Differentiation Between Non IgE Gastrointestinal Cow's Milk Protein Allergy and Milk IntoleranceAin Shams University
- Milk for Diabetes PreventionAlbert Einstein College of Medicine
- Lactose Intolerance and Intestinal PermabilityBezmialem Vakif University
- Screening of Lactose Intolerance Among IBS Patients Diarrhea DominantAssiut University
- Efficacy of a Low FODMAP Diet in the Absence of Lactose Malabsorption in Moderate to Severe ROME IV IBS.Universitair Ziekenhuis Brussel
- Goat vs. Cow Milk Digestive ToleranceInstitut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement
Research already completed
- Efficacy of a Probiotic Formulation in Adults With Lactose Intolerance and Methanogenic Intestinal OvergrowthUniversidad de Concepcion
- Testing the Capability of the Smart Underwear Device to Detect Increased Microbiome Activity Following Lactose ConsumptionUniversity of Maryland, College Park
- Low-grade Inflammation and Gut Symptoms From A2 and Hydrolyzed A1 MilkUniversity of Turku
- Lactase Enzyme Supplementation for Growth and Feeding Tolerance in Preterm InfantsCairo University
- Dietary Management of Well Nourished Children With Persistent Diarrhea and Secondary Lactose Intolerance With Different Feeding Formulas.( Hospital-Originated Modified Feeding HOMF)Children's Hospital and Institute of Child Health, Multan
- Trial of Rice-Based F-75 in Severe Malnutrition & Persistent Diarrhea in Children (SAM-RICE Study)Children's Hospital and Institute of Child Health, Multan
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- Lactose IntoleranceNational Institute of Diabetes and Digestive and Kidney Diseases
- Lactose IntoleranceMayo Foundation for Medical Education and Research
Diagnosis and Tests
- Food Allergy TestingNational Library of Medicine
- Lactose Tolerance TestsNational Library of Medicine
Related Issues
- Allergic to Milk? Some Dark Chocolate Labeled as Dairy-Free May Still Contain MilkFood and Drug Administration
- Food Intolerance vs. Food Allergy: What's the Difference?Mayo Foundation for Medical Education and Research
- Milk AllergyMayo Foundation for Medical Education and Research
Genetics
- Lactose intolerance: MedlinePlus GeneticsNational Library of Medicine
Clinical Trials
- ClinicalTrials.gov: Lactose IntoleranceNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Lactose Intolerance. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Lactose Intolerance, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.