Food Allergies Or Food Intolerance: What Is The Difference?

August 5, 2021

Abdominal Pain Symptoms

Feeling an unpleasant sensation in your stomach after a delicious meal is often a downer. If this is a common occurrence, you may attribute it to a digestive disorder or an allergy. While it is good to have an idea of your discomfort and why it exists, pinpointing the cause on your own is always risky. Self-diagnosis is not always accurate, so it will be better to do some research before jumping to conclusions hastily.

Food allergies and food intolerance are commonly mistaken for each other as they share common side effects like stomach pain and diarrhoea. Naturally, these terms have been used interchangeably, and hence, potentially causing greater confusion when trying to understand your discomfort.

As such, here are a few key differences between food allergies and food intolerance to help you assess your condition better. For that, we will first dive into what exactly food allergies and food intolerances are.

What is a food allergy?

Food allergies are a result of an abnormal response by your immune system to certain foods. For instance, your immune system may overreact and mistake your food substances as harmful bacteria or antigens, triggering your body to produce excess immunoglobulin E (IgE). When the IgE is released, it serves as the first line of defence against antigens entering the body. This is an IgE-mediated food allergy with symptoms that appear immediately or up to two hours after eating the offending food.

Upon subsequent consumption of the same food, the allergen will interact with IgE at the surface of the immune cells. IgE will remind the cells to release histamine to defend the body against these allergens. Histamine helps protect your body against harmful bacteria and allergens, but when produced in excess, allergic reactions are triggered. Some examples include rashes, facial swelling, and digestive side effects such as diarrhoea.

Similarly, non-IgE-mediated food allergy involves your immune system overreacting to certain food substances. However, the symptoms of this type of food allergy are more delayed – signs may take up to two days to be observed.

What is food intolerance?

On the other hand, food intolerance is not caused by an immune response. Instead, food intolerance occurs when the digestive system cannot digest the food properly. This is due to a lack of enzymes in the body to digest the food entirely.

For example, lactose intolerance is the inability to digest dairy products such as milk and cheese completely. Lactose intolerant individuals do not produce sufficient lactase in their digestive tract to break down lactose, a sugar found in dairy products. As a result, they will display digestive issues such as diarrhoea, flatulence, and even nausea. Food intolerance symptoms typically develop slower than symptoms of food allergies.

Differences in triggers

Many different types of food can trigger food allergies. However, not everyone with food allergies is allergic to the same food, and some may be allergic to more types of food than others. Some common triggers that account for up to 90% of allergic reactions include wheat, milk, soy, fish and shellfish, nuts and eggs.

On the other hand, food intolerance is mainly triggered by specific compounds in the food. Aside from lactose, other common compounds that trigger food intolerance include gluten and fructose. Gluten is a protein usually found in grains such as wheat, barley, and rye, while fructose is present in fruits, vegetables, and honey.

For people who suffer from food allergies or food intolerance, it is best to read food labels and be aware of the different ingredients and potential allergens present in their food. If they are dining out, it will always help to clarify with the staff to prevent any adverse side effects.

Differences in symptoms

Aside from digestive-related symptoms like diarrhoea and nausea, food allergies may also result in rashes and hives. If the allergies are more severe, the breathing and circulatory systems of individuals would be affected.

It is important to note that allergy responses may not always happen during the first time after consuming a food. It is possible to suddenly develop allergic reactions to a certain type of food even after eating it for many years without any visible issues. Some people may even outgrow their food allergies. For example, many children are allergic to eggs in their early childhood, but their immune system responds fine to the food in adulthood.

For those suffering from food intolerance, it is usually diagnosed in adulthood and most symptoms are related to the digestive system. If other organs are affected, the symptom is most likely an allergic reaction. Other signs of food intolerance to look out for include headaches and fatigue, which will usually accompany the typical symptoms related to the digestive system.

Self-diagnosis can be risky, so if your symptoms do not match the typical descriptions of a food allergy or food intolerance, it is best to consult a health professional for a more accurate diagnosis. To better understand any underlying problems, you can look up the symptoms of other digestive conditions. Gastrointerstinal cancer symptoms and pancreatic cancer symptoms can be similar to those of food allergies and intolerances, but they are often accompanied by other signs such as weight loss and jaundice.


Both food allergies and food intolerance have common visible symptoms such as bloating, abdominal pain, and diarrhoea. However, food allergies usually have more severe effects as they affect other organs aside from the digestive system, such as the respiratory system.

An allergic reaction could also become life-threatening if medication is not administered in time. Hence, being aware of the differences between the two conditions could help save your life or your loved ones as you identify the appropriate treatment.