What are food allergy symptoms?

Woman with food allergy symptoms sitting on her bed bending forward in pain as she holds her stomach

If after eating, you feel a tingling in your mouth or stomach pains you could be experiencing food allergy.

Food allergy symptoms affect many parts of the body. In some people the reaction is so severe they can develop anaphylaxis.

To help you understand what food allergy symptoms are, we explain where symptoms appear on the body and signs of anaphylaxis. Later, we talk about how quickly food allergy symptoms develop and what happens when you eat a trigger food.

Towards the end of the article, you’ll learn about common trigger foods and how doctors test and treat food allergy.

How do food allergy symptoms affect the body?

Symptoms of food allergy can affect many areas of the body. For this reason, it’s good to be mindful and pay attention to how you feel after eating or drinking.

Food allergy symptoms can affect the:

  • Mouth: A tingling or itching feeling
  • Skin: A raised, flushed, itchy rash (hives) and swelling
  • Throat: Difficulty swallowing and swelling
  • Lungs: Wheezing or shortness of breath
  • Head: Feeling dizzy and lightheaded
  • Stomach: Abdominal pain, diarrhea, feeling sick (nausea) or vomiting

Symptoms of anaphylaxis – a severe allergic reaction

Anaphylaxis is a life-threatening systemic reaction and medical emergency.

Signs of anaphylaxis include:

  • Skin reactions, including hives and itching and flushed or pale skin
  • Low blood pressure (hypotension) or a drop in blood pressure
  • Constriction of your airways and a swollen tongue or throat, which may cause wheezing and trouble breathing
  • A weak and rapid pulse
  • Nausea, vomiting or diarrhea
  • Dizziness or fainting

Symptoms of food allergy can affect many areas of the body. For this reason, it’s good to be mindful and pay attention to how you feel after eating or drinking.

If you have a serious food allergy, you'll most likely be prescribed an epinephrine auto-injector. It’s important to always carry two epinephrine auto-injectors. One may not be enough.

Teaching your family and friends how to use an auto-injector is a good idea as it prepares them for any food allergy emergencies. You should explain the method of delivery, as prescribed. This usually involves injecting the thigh with the auto-injector.

You should always seek medical help after using an auto-injector, even if you feel better, as you could experience an additional delayed reaction.

Wearing a medical alert bracelet or carrying an allergy alert card, is a good way of letting people know you have a severe food allergy.

How soon do food allergy symptoms develop?

Typical food allergy symptoms usually develop within two hours of eating a food allergen. Though, it can be little as 30 seconds.

However, as always, there’re some very rare exceptions associated with more unusual types of food allergies. In those cases, food allergy symptoms can develop after a longer period of time.

How does a person develop food allergy symptoms?

If a person has severe allergic reactions to food, such as peanut allergy they usually won’t develop food allergy symptoms the first time they eat peanuts.

Why? Because the body needs time to build antibodies against the trigger food. Antibodies play a crucial role in your immune system and their purpose is to kill harmful bacteria and viruses. But when a person has food allergy, their immune system mistakenly identifies certain foods as a threat. After this, it begins to build Immunoglobulin E (IgE) antibodies that target the food allergen.

When you next eat your trigger food, the IgE antibodies spring into action. They alert other cells to release chemicals such as histamine. This is when you may experience food allergy symptoms.

Sometimes people who develop IgE antibodies never experience food allergy symptoms, despite being sensitized to the allergen. Researchers are still investigating why this happens.

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Ingredients that typically cause food allergy symptoms

The most common food allergens are a mixture of animal and plant-based products. Food manufacturers are required by law to list these ingredients on food packaging labels.

Animal-based products

These animal products typically come from cows, poultry and some fish, and include:

  • Cow’s milk
  • Eggs
  • Fish
  • Shellfish

Plant-based products

These products are a mixture of nuts, seeds, grains, legumes, vegetables and preservatives, and include:

  • Peanuts
  • Wheat
  • Soybean
  • Tree nuts
  • Sesame – Food manufacturers will need to declare sesame on labels in 2023

Can spices cause food allergy symptoms?

If you’ve been avoiding a certain food but are still noticing food allergy symptoms you may be reacting to the spices added to your meals. Not the food itself.

Spices that can cause food allergy symptoms include: Oregano, thyme, coriander, cumin, cayenne pepper, paprika, caraway seed.

An expert guide to
food intolerance

Food allergies are different to intolerance which gives some people, like this woman on her sofa, stomach ache after drinking milk

However, allergies to spices are rare and often caused by a cross reaction. This cross reaction is called oral allergy syndrome (OAS) or pollen food syndrome (PFS). Certain proteins in the spice you react to can be similar to proteins in your problem pollen. Oral allergy syndrome is usually not severe. You might get a mild, local reaction in your mouth and throat, lips and face.

What are symptoms of non-IgE-mediated food allergies?

So far, this article has focused on symptoms of IgE food allergies, however there are some types of food allergy that don’t involve IgE antibodies.

In non-IgE-mediated food allergies, different cells of the immune system activate and can cause an allergic reaction that can take hours or even days to develop.

People with a non-IgE-mediated food allergy may develop a rash on their skin and gastro-intestinal problems after eating their trigger food.

Gastro-intestinal symptoms include:

  • Heartburn
  • Indigestion
  • Diarrhea
  • Vomiting

While people don’t experience anaphylaxis with non-IgE-mediated food allergies, they can develop anaphylactic-like symptoms that are very similar and equally as serious.

One other type of food allergy that can trigger anaphylaxis is an exercise-induced food allergy. This is a rare food allergy that occurs when a person eats a trigger food before exercising.

If someone has mixed IgE and non-IgE-mediated food allergy they can experience symptoms from each type of food allergy.

How to avoid food allergy symptoms in four steps

If you think you or a loved one has food allergy, please do get this confirmed by your healthcare provider first. They’ll explain how to avoid your trigger foods and offer treatment advice.

Here are our top four tips to help you avoid food allergy symptoms:

  1. Carefully read labels:Read and reread food labels. Food manufacturers list common food allergens on labels to help you avoid them. If you’re unsure about any of the ingredients on the labels, contact the food manufacturer so they can explain them to you.
  2. Take care when eating in restaurants:It’s possible to consume traces of trigger foods through cross-contamination – so tell servers about allergies when making a booking or reservation. Also, always mention your allergies again when ordering food.
  3. Triple check non-food product labels:Unlike food manufacturers, product manufacturers don’t have to list every single allergen on their labels. If in doubt, contact the manufacturer for a complete list. These products range from cosmetics to cleaning products, and even include pet food.
  4. Manage your pollen allergies:Sometimes when you experience an allergic reaction to fruits, vegetables or nuts it’s because the body confuses them for pollen. When this cross-reactivity happens, you may have oral allergy syndrome (OAS), pollen food syndrome (PFS) – another name for the same condition. However, please do speak with your healthcare provider, so they can investigate if your symptoms are caused by an allergy to pollen or to a specific food instead.

How to treat food allergy symptoms

When your healthcare provider diagnoses food allergy the advice they give will depend on whether your symptoms are mild or severe.

Mild symptoms: If your food allergy is mild your healthcare provider may suggest you take antihistamines to reduce your body’s reaction to the trigger food. Usually, a treatment plan will include a mixture of treating symptoms when they occur and avoidance strategies.

Severe symptoms: If your food allergy is very severe, your healthcare provider will suggest you avoid the food altogether – even in trace amounts. Additionally, they’ll also prescribe an auto-injector containing epinephrine. Don’t forget, it’s important to always carry two autoinjectors in case you accidently consume your trigger food. You should also consider wearing a medical alert bracelet or carrying an allergy alert card, so people know you have a serious food allergy.

For people with peanut allergy, they could also try allergy immunotherapy. This treatment involves repeated, controlled doses of the allergen. The aim is to desensitize the body to peanuts to help prevent a serious reaction if they’re accidently eaten.

Woman wondering about the difference between skin prick and blood allergy tests.

How does allergy
testing work?

How to test for symptoms of food allergy

To diagnose food allergy your healthcare provider can use a combination of tests and sometimes suggest dietary changes.

These tests include:

  • A skin prick test: A small drop of liquid that contains the allergen, or a diluted sample of the fresh food, is placed onto the skin – usually the arm. Then the skin underneath is pricked gently. If the skin reacts to the allergen you are sensitized.
  • Blood tests: Another way to detect sensitization to a particular food allergen is to test the blood for IgE antibodies.

It's important to remember that if you’re sensitized to a particular food it doesn’t necessarily mean you’re allergic to it. You only have food allergy if you experience symptoms.

Keeping a food diary is a useful way to record how you feel after eating different types of foods and will help your healthcare provider diagnose the cause of your symptoms. They’ll likely also want to find out more about your medical history, so if possible make a note of any food allergies that run in your family.

When testing is inconclusive, your healthcare provider may try other approaches to find out what is making you feel unwell.

For example, they may suggest an elimination diet. During an elimination diet, the suspected trigger food is removed and slowly reintroduced. This is typically used to detect intolerances. However, to diagnose lactose intolerance they would typically use breath and blood tests instead.

Non-IgE-mediated allergies are harder to diagnose. Here, your healthcare provider may suggest an oral food challenge. In an oral food challenge you’ll eat small amounts of the problem food, which gradually increase until you experience a mild reaction. If symptoms develop, you’re possibly allergic to that food.

Depending on your medical history they may also want to look at your digestive tract with a camera. This procedure is called an endoscopy.

Food allergy symptoms or food intolerance symptoms?

After several consultations and tests, you may have reached the point where food allergies can’t explain your symptoms. Instead, you may have food intolerance.

Food intolerance symptoms tend to range from mild to moderate and take longer to develop than food allergy symptoms. Some people can even eat a small amount of food they’re intolerant to, unlike food allergy where the slightest morsel can trigger a range of symptoms.

To confirm food intolerance a healthcare provider may recommend an elimination diet or a breath or blood test.

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