Food Allergy or Food Intolerance?

Do you know the difference between food allergy and food intolerance?

The mechanism behind the two is significantly different. Allergies involve a reaction from your immune system after exposure to a unique protein component of a specific food. On the other hand, food intolerances does not involve the immune system. Some people experience food intolerances because natural food chemicals and/or additives irritate nerve endings, similar to medication caused side effects. It is unlikely adults develop food allergies in their adulthood, but if you do suspect an allergy please speak with your doctor as it can be life threatening. ⁠

Food allergy are commonly diagnosed through a skin prick test by a doctor. On the other hand, there are no tests for food intolerances and are diagnosed through an elimination diet guided by a dietitian.


People who experience food intolerances would present with symptoms from 4 domains: ⁠

  • digestive system (e.g. reflux, IBS, diarrhoea)⁠

  • skin reactions (e.g. eczema, hives, swelling)⁠

  • respiratory tract (e.g. sinus congestion, asthma, throat irritation)⁠

  • nervous system (e.g. headache, fatigue)⁠

  • Other possible symptoms: mouth ulcers, nausea and bladder irratation.⁠

Elimination diets involves removing the food group of interest for a period of time and reintroducing slowly to determine your personal threshold. Every individual's threshold of food intolerance can vary. Common elimination diets including the Low FODMAP diet for IBS, FAILSAFE / RPAH (Royal Prince Alfred Hospital) / Food chemicals elimination diet and whole foods such as dairy and gluten. You can read more about the RPAH Food Chemical Intolerance Diet here.


Food chemical elimination diets are highly restrictive and require careful guidance of a dietitian to ensure you are still meeting your nutrition requirements whilst going through the diet. The type of foods that will be temporary eliminated in your diet will vary and a dietitian can help determine which is appropriate for you. Furthermore, due to the highly restrictive nature and a process that can take few months to complete - it is recommended that individuals trial other dietary interventions first before going through an elimination diet. Some suggestions include healthy balanced meals from the five core food groups, avoiding highly processed foods, eating at regular meal times, staying hydrated and limit caffeine/alcohol.


Interested in starting an elimination diet? Book an appointment with our Accredited Practising Dietitian who are experienced with managing food intolerances (incl. food chemicals and low FODMAP)