Welcome to Sydney Gut Clinic

Opening Hours : Monday to Friday - 8am to 5pm
  Contact : 02 9131 2111

Common food intolerances

Common food intolerances: Causes and remedies

Common food intolerances, often mistakenly referred to as food allergies, refer to the difficulty in digesting certain food items that trigger an unpleasant physical reaction. While food tolerances may not be life-threatening, they can lead to symptoms like bloating and abdominal pain, which occur a few hours after eating these types of food. 

Food intolerance is also known as non-mediated food hypersensitivity or non-allergic food hypersensitivity. The difference is that food allergies trigger an immune system reaction whereas food intolerances do not.


Symptoms of common food intolerances may take longer to appear compared to symptoms of food allergies, so it can be difficult to determine whether you have a food intolerance or an allergy because the signs and symptoms are often the same.

When it is an allergy, even ingesting minute quantities may result in symptoms, as can be seen in people with nut allergies. When it comes to common food intolerances, a minor quantity of food will usually not cause any symptoms or discomfort.

The onset of symptoms following common food intolerances typically occurs after several hours and in some cases, symptoms may even take up to 48 hours to manifest themselves. These symptoms may persist for several hours or even days.

Symptoms of common food intolerances include:

  • Stomach pain
  • Bloating
  • Gas or flatulence
  • Nausea or vomiting
  • Heartburn
  • Diarrhoea
  • Irritable Bowel Syndrome (IBS)
  • Rashes
  • Hives
  • Recurrent mouth ulcers
  • Headaches


It is unclear why a person demonstrates sensitivity to certain types of food. If your symptoms occur after eating dairy products, you may be lactose intolerant. This means that your body cannot digest lactose, a natural sugar found in milk, yoghurt, and soft cheeses.

Some people have trouble digesting wheat and experience bloating, gas, diarrhoea, and stomach pain after eating bread. Other common food intolerances include:

  • Lactose
  • Wheat
  • Gluten
  • Caffeine
  • Fructose
  • Histamine, present in mushrooms, pickles, and cured food
  • Salicylates
  • Sulphites
  • Additives


Food intolerances can often be difficult to diagnose. Certain substances within food and the quantity of food eaten can increase the frequency and severity of symptoms. Diagnosis of adverse reactions to food should be based on clinical history, response to treatment, and testing.

To make diagnosis more accurate, you may be asked to keep a diary and write down which food items are eaten, what your symptoms are, and when they appeared. The data in the diary can help your doctor identify which foods are causing adverse reactions and help you figure out your next steps.

Alternatively, you may be asked to go on an exclusion diet where you eliminate certain food items and observe your physical reaction or symptoms to pinpoint the particular food items that are causing you an intolerance.


If you can figure out which types of food you are intolerant to, you can easily manage your symptoms by avoiding those items for a while. 

You can then reintroduce this food in minor quantities and monitor how much you can eat without triggering any symptoms. There are instances when you may have no reaction when eating particular food items, which could mean that you’ve developed a tolerance. 

Maintaining tolerance is often a question of knowing how long to abstain and how much of it to eat when it is being reintroduced. As each person reacts differently, the only way to determine this is through careful trial and error.

Request more information on the causes and treatment options for common food intolerances

Identifying the food that causes you discomfort may help you improve your health and wellbeing when treating food tolerances. If you’re keen on understanding which types of food are causing your symptoms or your discomfort, consult our team of gastroenterologists for more information on the causes and treatment options for your food intolerance.