Symptoms of Lactose Intolerance


Find Allergy Clinics »

There is a wide variety of symptoms linked to lactose intolerance and can include:

  • Diarrhoea
  • Bloated stomach
  • Stomach pains and/or cramps
  • Flatulence
  • Nausea

The amount of lactose required to cause these symptoms varies from person to person. But generally, the severity of the symptoms depends upon: the amount of lactose ingested and how much lactase enzyme they have.

Lactose intolerance can cause symptoms similar to irritable bowel syndrome (a chronic digestive problem) and milk protein intolerance.

Gastroenteritis, a condition in which the intestinal lining is inflamed can be followed by temporary lactose intolerance. This is an example of secondary lactose intolerance. Lactose intolerance after gastroenteritis can complicate things, especially in children as the lactose intolerance can cause watery diarrhoea. Watery diarrhoea can be dangerous in children as it can lead to rapid dehydration. This is usually resolved by giving rehydration solution over 24 hours.

How do I know if I am lactose intolerant?

If you think you’re lactose intolerant you should go and visit your GP. It would be a good idea to keep a food dairy and take this with you to your appointment. This should include what you eat and drink, and any associated symptoms you experience. You should tell your GP which foods you think you are sensitive to. They may suggest following an ‘elimination test’ diet which would mean following a lactose free diet for 2 weeks.

Lactose Intolerance Tests

To find out what is causing your lactose intolerance and how deficient of the lactase enzyme you are your GP may ask you to do some further tests. These include:

  • Hydrogen breath test
  • Lactose tolerance test
  • Milk tolerance test
  • Stool sample
  • Small bowel biopsy

Living with lactose intolerance

There is no treatment for lactose intolerance, so the emphasis is placed on how to manage the condition. The main way to live with lactose intolerance is to avoid any dairy products by following a lactose-free diet. You get many of your daily nutrients from dairy products, so it is important to replace these foods with others high in those vitamins and minerals you’d usually be able to attain through dairy products. There are also alternatives to dairy products that are specially made to accommodate those who are lactose intolerant, like lactose-free milk.

Some who are lactose intolerant find they are able to tolerant a small amount of dairy foods. Sometimes you can even increase your tolerance to lactose containing foods by gradually reintroducing them into your diet.


« Types of Lactose Intolerance Lactose Intolerance Tests »