Food allergies and food intolerances are two terms that are sometimes used interchangeably. But in fact, they both describe different health conditions. In both cases, the body has a negative reaction to a certain type of food. However, the symptoms can be quite different, as can the best form of treatment. This post delves more into the difference between the two.

What is a food allergy?

A food allergy is an immune system ‘malfunction’ in which the body sees a certain safe substance as a threat and responds by releasing histamines. These histamines cause all kinds of reactions around the body in an attempt to expel the substance. However, sometimes the reaction is so severe that the body does not know how to protect itself and goes into anaphylactic shock – a condition which can be deadly without immediate treatment. 

Food allergies are often viewed as more serious than intolerances. While symptoms can be mild for some people, there is always a risk that a food allergy can evolve into a more serious ‘anaphylactic’ version, and therefore triggers must be avoided. 

Common symptoms of a food allergy

Food allergy symptoms tend to occur more quickly than intolerance symptoms – often within a few minutes to two hours. A few common symptoms of a food allergy include:

• Itchy skin
• Hives/rashes 
• Swelling of lips, face or eyes
• Stomach pain
• Diarrhoea
• Nausea 
• Runny/itchy nose
• Coughing/wheezing
• Anaphylactic shock (in severe cases)

You may experience one of these symptoms or several of these symptoms. In many mild cases, symptoms will go away within two hours, but sometimes they come back after four hours.

Mild allergies to common foods may at first go undetected – they may make your legs constantly itchy or cause some stomach pain, but may not otherwise be debilitating. However, allergic reactions can get more severe over time in some cases – particularly allergies to nuts or fish.

Anaphylactic shock is the most serious allergic reaction that a person can have. Breathing becomes severely restricted, blood pressure drops and a person may faint. Many people die from this allergic reaction if they are not given immediate treatment.

Common food allergy triggers

You can become allergic to pretty much any food from bananas to red meat. However, some food substances are more common for people to become allergic to. These include:

• Milk
• Eggs
• Soy
• Wheat
• Fish
• Shellfish
• Specific nuts (most commonly peanuts, tree nuts, walnuts, almonds, brazil nuts or pecans)
• Specific seeds (most commonly sesame seeds or sunflower seeds)

You can identify your trigger foods by keeping a food diary and looking back at any food consumed immediately before experiencing an allergic reaction. You should note that it could be an ingredient found within a sauce such as a spice or herb. If you experienced an allergy at a restaurant, consider requesting a full list of all the ingredients found in each dish you ate so that you can identify the trigger. 

How to treat a food allergy

There is no scientifically proven way to cure an allergy. You can however avoid reactions by avoiding triggers. It’s also possible to use treatments to help allergy symptoms clear away.

With mild food allergies, the best form of treatment is often oral antihistamines. These pills can be bought over the counter, although a doctor may be able to recommend stronger prescription versions. Antihistamines can help to get rid of histamines from your body, causing symptoms like hives and itchy sinuses to go away. 

As for anaphylactic shock, this cannot be treated with antihistamines. Instead, an auto-injector such as an EpiPen is needed to help a person get out of anaphylactic shock. This is a small device with a needle that injects epinephrine into a person’s bloodstream that must be prescribed by a doctor. Auto-injectors must be carried around at all times. It is worth training family members how to use them as you may not be able to use the auto-injector yourself. 

What is a food intolerance?

A food intolerance is more of a ‘digestive’ malfunction. The gut loses its capability to digest a certain substance, which can lead to all kinds of temporary digestive problems until the substance leaves the body. Some intolerances can also cause knock-on effects around the body including joint pain and migraines.  

Food intolerances cannot kill you like food allergies. However, the symptoms can still be very uncomfortable and debilitating, plus they tend to last longer than allergy symptoms. 

Common symptoms of a food intolerance

In some people, food intolerance symptoms can be immediate. However, many people with intolerances tend to experience more delayed effects – often not until 12 or even 24 hours after consuming the trigger food. Common symptoms include:

• Stomach pain
• Gas and bloating
• Diarrhoea 
• Heartburn
• Headaches/migraines
• Joint pain

Headaches and joint pain are more common with certain types of intolerance triggers like MSG and gluten. IBS-related symptoms are by far the most common types of symptoms related to food intolerances.

Common food intolerance triggers

As with allergies, you can develop intolerances to all kinds of foods. However, there are some triggers that are definitely more common. These triggers are typically chemicals or unique ingredients found within foods. Common examples include:

• Lactose (found in milk and dairy products)
• Gluten (found in many wheat and barley-based products like bread and pasta)
• Caffeine (including caffeine in coffee, tea, soft drinks and even chocolate)
• Alcohol (found in any alcoholic drink)
• Sulphites (found in a cider, beer and wine)
• Histamines (the same chemicals that causes allergic reactions can cause intolerances and is commonly found in wine and cheese)
• MSG (used in a lot of Chinese food, but also many sauces and processed meats)
• Salicylates (found in some fruit and vegetables including strawberries, cauliflowers and watermelons)

Food intolerances can sometimes be harder to identify than allergies. This is because there is a much larger window of time to consider – a trigger could be any ingredient you have eaten within the last 24 hours before experiencing a flare-up. The best way to identify the trigger is to keep a food diary that records everything you eat. You can then look out for trends in meals that you’ve recently eaten every time you experience symptoms.

Some people with intolerances can still continue to consume small amounts of trigger foods without experiencing a flare-up. This is different to a food allergy, which often triggers a reaction – no matter how much or how little of a substance you have consumed. 

How to treat a food intolerance

Unfortunately, once you develop a food intolerance, you usually have it for life. By avoiding triggers, you can prevent flare-ups. There are many diet plans online that you can follow.

Certain over-the-counter medications can be used to treat symptoms. If you experience diarrhoea, it is worth taking anti-diarrheal pills so that you’re not having as many frequent bowel movements. Anti-inflammatory painkillers like ibuprofen can meanwhile ease gut pain, joint pain and potentially headaches caused by an intolerance. Specific medication can be bought for certain types of intolerances such as lactase enzyme tablets for a lactose intolerance.

Food allergy vs food intolerance: What’s the difference?

The main differences between a food allergy and an intolerance can be summarised like this:

• Allergies are a malfunction of the immune system, while intolerances are a malfunction of the digestive system.
• Allergies are more likely to cause symptoms like itchiness, swelling or breathing difficulties. Headaches and joint pain are more likely to be caused by an intolerance. Both can cause digestive issues including diarrhoea and stomach pain. 
• Allergy symptoms display with two hours, whereas intolerance symptoms can be immediate or they can take up to 24 hours to display
• An allergy can be life-threatening as it may lead to anaphylaxis. Food intolerances are never life-threatening. 
• Allergies are treated with antihistamines or an auto-injector. Intolerance symptoms can be relieved with anti-diarrheal medication, anti-inflammatory painkillers or specialist medication like lactase enzyme tablets.