Symptoms

People with lactose intolerance may feel uncomfortable within 30 minutes to two hours after consuming milk and dairy products. Symptoms range from mild stomach rumbling to severe stomach pains, nausea and diarrhoea.

The severity of the symptoms may be proportional to how much lactose was consumed and how much lactose the individual can tolerate (i.e. how much lactase their body produces). If an individual has very low levels of lactase, this could mean a severe intolerance and marked symptoms. However, lactase levels and the severity of symptoms don’t always correspond.

Most Common Symptoms of Lactose Intolerance:

  •     Bloating
  •     Flatulence (wind)
  •     Diarrhoea
  •     Stomach cramps
  •     Vomiting


Lactose intolerance is often confused with irritable bowel syndrome (IBS) or Coeliac disease, which have similar symptoms including a bloated stomach, flatulence (wind) and stomach cramps.

Find out more about Irritable Bowel Syndrome (IBS) and Coeliac disease.

Conversely, some symptoms commonly blamed on lactose intolerance are, in fact, not caused by the intolerance. Problems like eczema, excessive mucous or intense fatigue are not actually symptoms of lactose intolerance.