Last updated: 11 February 2014
The symptoms of lactose intolerance will occur after consuming food or drink that contains lactose, such as dairy products.
The main symptoms include:
diarrhoea three or more times a day
- bloated stomach
- stomach pains
- stomach rumbling
- feeling sick
- stomach cramps
The severity of your symptoms and when you begin to experience them will depend on the amount of lactose that you have consumed.
The amount of lactose that it takes to cause your symptoms will vary from person to person. For example, some people may still be able to drink a small glass of milk without triggering any symptoms, while others may not even be able to have milk in their tea.
Conditions that cause similar symptoms
The symptoms of lactose intolerance can be similar to those of other conditions, such as irritable bowel syndrome (IBS) or milk protein intolerance. IBS is a chronic (long-term) disorder that affects the digestive system.
Milk protein intolerance is an adverse reaction to the protein in milk from cows, but it does not involve the immune system (and so is not the same as milk allergy). Due to the similarities, these three conditions can sometimes be confused.
This is why it is always important to get a medical diagnosis if you think that you or your child may have lactose intolerance.
Read more about diagnosing lactose intolerance.
Continue to next section: Causes of lactose intolerance