Lactose Intolerance

Lactose intolerance occurs when the body cannot digest lactose, the natural sugar found in milk and dairy products. This happens when levels of lactase, the enzyme that breaks down lactose, are low. Lactase activity is high in infancy and naturally declines after weaning in many people.

Lactose intolerance is common worldwide. Prevalence varies by ethnicity—from under 5% in Northern Europe to over 90% in parts of Asia. Symptoms usually appear 30 minutes to 2 hours after consuming lactose‑containing foods.

It is important to distinguish lactose intolerance from other gastrointestinal conditions, as symptoms can overlap with disorders such as irritable bowel syndrome (IBS) or coeliac disease.

Common Symptoms of Lactose intolerance

Symptoms depend on the amount of lactose consumed and individual tolerance levels. Typical symptoms include:

abdominal bloating
abdominal pain or cramping
diarrhoea
flatulence
nausea
vomiting
steatorrhoea (fatty stools) in some cases

Infants and young children may also show poor weight gain or feeding difficulties.

Conditions With Similar Symptoms

Several conditions can mimic lactose intolerance:

Coeliac disease
Cow’s milk protein allergy (casein or whey)
Irritable bowel syndrome (IBS)
Crohn’s disease
Ulcerative colitis

A structured assessment helps determine whether symptoms are due to lactose intolerance or another gastrointestinal condition.

Diagnosis of Lactose intolerance

Diagnosis may be based on:

symptom improvement after reducing lactose
hydrogen breath testing
stool acidity testing in infants
exclusion of other gastrointestinal disorders

Your clinician will recommend the most appropriate approach based on symptoms and medical history.

Management and Treatment of Lactose intolerance

Most people manage lactose intolerance through dietary adjustment, not complete avoidance. The level of restriction depends on individual tolerance.

Management options include:

reducing or spacing out lactose intake
choosing low‑lactose or lactose‑free dairy products
using lactase enzyme supplements (e.g., lactase tablets or drops) to help digest lactose
ensuring adequate calcium and vitamin D intake through diet or supplementation

Many patients can still enjoy dairy foods with the right guidance and support.

LACTOSE-RESTRICTED DIETARY GUIDELINES

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REFERENCES

NICE Clinical Knowledge Summary – Lactose Intolerance https://cks.nice.org.uk/topics/lactose-intolerance
British Dietetic Association – Lactose Intolerance https://www.bda.uk.com
European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) – Lactase Deficiency Guidance https://www.espghan.org
National Institutes of Health (NIH) – Lactose Intolerance Overview https://www.niddk.nih.gov

Last reviewed: February 2026