Food Allergies: Symptoms, Types, Diagnosis & Home Remedies

Introduction

Have you ever experienced itching in your mouth or rashes after eating certain foods? Maybe it was peanuts, shellfish, or even milk. These may be the signs that your body is warning you about having a food allergy.

Food allergies occur when your immune system mistakenly detects harmless foods as a threat and reacts against them¹. Most food allergies happen because of a substance in your body called IgE (an antibody). However, some allergies happen in different ways or through a mix of reactions, sometimes involving other parts of the immune system, called T cells².

While some reactions are mild, there may be certain conditions which might turn dangerous or severe¹. This is why recognising or identifying a food allergy is very important.

This blog will help you understand what exactly food allergies are, how to recognise them, what are their types, common foods that can cause allergies and when to seek medical attention.

What Is a Food Allergy?

As mentioned earlier, food allergy is a condition that occurs when your immune system mistakenly detects harmless food you eat as a threat. While your immune system normally protects you from harmful substances, here some food items you consume are flagged as harmful by the body, leading to allergic reactions. This condition usually causes only mild reactions. But in some cases, it may become dangerous or life-threatening, causing severe reactions (anaphylaxis)¹.

People often get confused between food allergies and food intolerances. These are different in the following ways:

Now you might be clear with the food allergy meaning. Even if you think you cannot distinguish whether you have an allergy or intolerance, do not wait for the symptoms to get worse, immediately consult your doctor for confirmation, as unattended allergies can be life-threatening.

Food Allergy Symptoms

Food allergies bring about several symptoms. These food allergy symptoms can be classified as follows:

1. Skin Symptoms

These are the most common indications of food allergies³.

• Hives: Raised, itchy red rashes
• Itching: Itchiness inside the mouth, throat or ears
• Angioedema: Swelling on face, around the eyes, lips, tongue, and inside mouth⁵
• Flushed skin: Redness on the skin¹

2. Digestive Symptoms

These might occur alongside skin symptoms. Appear within half an hour of consuming food³.

• Abdominal pain: Stomach cramps and belly pain
• Vomiting and nausea: Common reactions soon after ingestion
• Diarrhoea: Loose motion¹

3. Respiratory Symptoms

These are crucial as they can progress to life-threatening conditions.

• Wheezing: High-pitched noise or sound while breathing (exhalation)⁴, caused by narrowing of airways.
• Shortness of Breath: Difficulty in breathing¹
• Cough: Repetitive or persistent cough, sometimes combined with wheezing^3,4.

4. Severe Symptoms

These are much dangerous symptoms that should not be ignored, as they may be a sign of anaphylaxis, a rapid and severe allergic reaction affecting the whole body and can be fatal. Symptoms include:

• Narrowing or swelling of airways restricting breathing³
• Swelling of the throat causing breathing difficulties
• Sudden and severe coming down of blood pressure (BP)
• Unable to respond (loss of consciousness)¹
• Body turning pale and feeling weak, loose, or not firm (particular symptom in children)⁴
• Persistent fainting, dizziness and weak pulse^4,6.

Note: Although some symptoms are classified into different categories (apart from being listed under the severe section), this does not mean they are less dangerous. Any allergic symptom can progress to severe reactions. Therefore, it is important to consult your doctor if you think the allergy symptoms or reactions are persisting for a while or are getting worse.

Types of Food Allergies

Based on the reaction timing, the food allergies can be classified into three categories. They are:

1. IgE Mediated Food Allergies

These are types of food allergies which involve a wide range of signs and symptoms. This type of food allergy is one of the main causes of severe allergic reactions that may lead to a need to go to the emergency room (especially in children)².

• Mechanism: The immune system wrongly reacts to a certain food and makes special antibodies called IgE. These antibodies get attached to certain types of cells in the body, called mast cells. The next time the same food is consumed, these antibodies trigger the cells to produce a chemical called histamine, which causes the allergic reaction².
• Symptoms: They can appear even with minute quantities and appear soon after consumption or within 2 hours. Include both mild and severe symptoms such as hives, swelling, diarrhoea, vomiting, abdominal pain, etc.
• Examples: Allergies related to peat nuts, tree nuts, shellfish, eggs, etc. Can cause a particular condition called oral allergy syndrome (people allergic to pollen react to raw fruits and vegetables because their proteins are similar to pollen; cooked forms may be tolerated)².

2. Non-IgE-Mediated Food Allergies

These are types of food allergies which do not involve IgE antibodies, but other parts of the immune system. Therefore, they are harder to diagnose because there are only a few easy, painless tests to confirm them.

• Mechanism: Since they do not involve IgE, they are said to cause allergic reactions by other components of the immune system. This causes delayed reaction, mainly in the digestive tract⁷.
• Symptoms: As it is delayed, they may take more time to bring on the symptoms, mostly 48-72 hours, rather than immediately. In acute (sudden) reactions like food protein-induced enterocolitis syndrome, symptoms usually start 1-4 hours after eating the trigger food. Include symptoms like upper stomach pain, feeling sick, vomiting, blood or mucus in the stool, etc.
• Examples: Allergies related to cow milk, soy, rice, etc. can cause conditions like food protein-induced enterocolitis syndrome (FPIES), food protein-induced allergic proctocolitis (FPIAP), etc⁸.

3. Mixed Food Allergies

These allergies are caused when immune reactions or allergy contributions in some foods are mediated by IgE and some other parts of the immune system, making them mixed.

• Mechanism: These allergies cause inflammation backed by IgE antibodies as well as by other immune cells of the immune system, which may contribute to both sudden and delayed reactions⁸. Once the food is ingested, it connects to the IgE antibodies, which are already attached to mast cells that release histamine, causing inflammation and allergic reactions. At the same time, other cells of the immune system, such as T Cells, reacts to food, causing slow, delayed symptoms².
• Symptoms: Involve sudden and delayed ones such as vomiting, nausea, stomach discomfort, and redness, rashes, and irritation of the skin, etc.
• Examples: Allergies related to milk, wheat, soy, etc. Can cause conditions such as eosinophilic esophagitis, eczema, eosinophilic gastroenteritis^8,9.

Common Foods That Cause Allergies

The following is a list of foods that can cause allergies especially in sensitive individuals:

1. Nuts and Peanut

Peanuts are the most common and dangerous ones causing allergies. Even a small amount may trigger the immune system, causing severe, life-threatening reactions. Commonly consumed nuts that cause allergies include almonds, cashews, Brazel nuts, pistachios, walnuts, etc. may also cause allergic reactions. Symptoms include hives, redness, itching, breathing problems (asthma, wheezing, etc.), digestive symptoms and sometimes severe reactions like constriction of airways, BP fall¹⁰.

2. Cow’s Milk

Allergy to cow’s milk can be seen in one in fifty babies, while this is rare in adults¹¹. Some people, who are allergic to cow milk might develop allergies if they consume milk of other animals like goat, sheep, or buffalo. However, this isn’t same for all (reactions are more common with goat and sheep milk, while buffalo milk may or may not cause a reaction). Symptoms caused by this allergy can vary from mild to severe, which include hives, itching, redness, swelling of the face, stomach discomfort and serious or life-threatening symptoms like breathing difficulties, paleness, loss of consciousness, etc. Foods containing cow’s milk that can cause allergy include cheese, chocolate, ghee, ice cream, butter, yoghurt, etc¹¹.

3. Fish and Shellfish

Allergies to fishes and shellfish can be seen more in adults and adolescents than in kids. It is said that one in every hundred people may have this allergy¹². Symptoms can range from mild to severe, such as hives, lip swelling, itchiness, runny nose, breathing problems, throat tightness, stomach pain, vomiting, dizziness, body turning pale, losing consciousness, etc. The fish causing allergies include salmon, mackerel, tuna, trout, snapper, etc. The shellfish causing allergies include crustaceans (prawns, crab, lobster) and molluscs (squid, cuttlefish, mussels)¹².

4. Wheat

Wheat allergies are most commonly seen in children however, about two-third of them overcome these allergies as they grow old¹³. These allergies are caused by immune reactions to several wheat proteins such as gluten (most relevant), albumins, globulins, etc. Even though people with wheat allergies can eat other grains, some can be having problems. The symptoms of wheat allergies can range from mild to severe, which include hives, stomach problems (vomiting, nausea, pain and diarrhoea), asthma, headache, and other life-threatening problems causing breathing difficulties and shock. The foods which may produce these symptoms include pasta, bread, crackers, hot dogs, ice creams, etc¹³.

5. Egg

Egg allergies are one of the common types of allergies, caused by presence of certain proteins in egg. Those who are allergic to chicken eggs may develop allergies to other types of eggs, such as from goose, turkey, or quail. The common symptoms produced by egg allergies include mild and severe ones, such as vomiting, stomach cramps, persistent cough, breathing difficulties, skin turning pale, lip or tongue swelling, weak pulse, confusion, etc. The foods containing eggs which may cause these symptoms include soups, salads, ice cream, meatballs, egg curry, etc¹⁴.

6. Soy

Soy-related allergies are commonly found in infants, and they may overcome these allergies as they grow old. The symptoms caused by soy allergies can be mild or severe such as skin problems (hives, rashes, itching, redness), cold symptoms (sneezing, runny nose, watery eyes, etc.), gastric problems (vomiting, nausea, stomach discomfort, etc.), and serious, life-threatening problems (skin colour change, body shock, falling unconscious, weak pulse, etc). Foods that may cause these allergies include tofu, natto, soybeans, soya, soybean curd, etc¹⁵.

How to Test Food Allergies?

The following are some common methods used for food allergy testing:

• Skin Prick Test: This is a common type of testing method used. In this, a healthcare professional places a drop of water with a food allergen on the skin, mostly over the forearm. Then the skin is gently pricked so the allergen can enter the skin. Then it is observed for 15- 30 minutes, to check for the appearance of symptoms. The test may be performed for more than one food item that is said to cause allergies. If the skin turns red, bumpy, or itchy (wheal-and-flare reaction), then it may indicate a sensitivity to the allergen, but it does not always mean to have a food allergy. Therefore, the doctor may also consider symptoms and medical history¹⁶.
• Blood Test: A paramedic may collect a blood sample. This blood may then be evaluated for the amount of total and food-specific IgE antibodies in the blood. A person with a food allergy is said to have more allergen-specific IgE levels in response to a specific food allergen than normal. However, the amount of IgE may not confirm food allergy or predict the severity. This test may be recommended along with the other tests to confirm a food allergy diagnosis¹⁶.
• Elimination Diet: This test is recommended to perform under an allergist. He might ask to stop all the foods that are suspected to cause the allergy for about 2 weeks. Then, he might ask to slowly introduce each food at a time. If the symptoms come back after starting a specific food item, that may indicate an allergy to that particular food. However, symptoms may also be caused by food intolerance. Therefore, he might recommend more tests for confirmation¹⁶.
• Oral Food Challenge: This is said to be the most accurate type of food test, which may be used alone to diagnose food allergies. The doctor might recommend eating small amounts of a suspected food, gradually increasing the amount. He closely watches for the allergic reactions. If the doctor finds allergic symptoms, the treatment may be initiated right away, based on the severity of the reaction. If the symptoms were not detected, the doctor might confirm that the allergy is negative¹⁶.

Home Remedies for Food Allergies

The following are some home remedies for the food allergy symptoms:

• Cold Compress: Place a cold compress, made of clean cloth dipped in cold water, for about 10 to 20 minutes over the itchy skin. May help reduce itchiness and inflammation.
• Proper Hydration: Drinking enough water may help the mucus get thin and making it easier to breathe and keeping the airways clear. It may also keep the nose lining and throat healthy. This may help reduce the irritation caused by allergies¹⁷.
• Quercetin-Rich Foods: Consume foods rich in quercetin, which is known to have anti-allergic properties (antihistamine). These might help reduce histamine release by suppressing the immune system. Foods include apple, berries, grapes, broccoli, etc¹⁸.
• Probiotics: Consume probiotic foods. They may help reduce the intensity of food allergy by supporting gut health and the immune system. These can include curd, yoghurt, buttermilk, fermented foods, etc¹⁹.
  Note: Those who are allergic to milk or fermented foods are recommended not take these foods. Confirm with your doctor before consuming such foods.
• Ginger: Consume ginger root along with other foods. They are known to have anti-inflammatory properties, which may help reduce the digestive problems, such as nausea and vomiting²⁰ caused by allergies.
• Vitamin C-Rich Foods: Consume foods rich in Vitamin C these are known to reduce inflammation as they have several antioxidants and also known to suppress the activity of histamines released, reducing the allergy symptoms. These include citrus fruits, strawberries, kiwi, broccoli, leafy greens, etc²¹.

Note: Although these might help reduce the symptoms of food allergy, they are never a placement for proper treatment. The most effective way known to reduce the food allergies is to avoid consuming such allergic foods. Remember that food allergy treatment at home is not a safe option. The home approaches might help alleviate certain skin and digestive-related symptoms however, they may get worse even if these are followed. Therefore, always consult a doctor if you are having severe allergic reactions, rather than completely depending on these home approaches. Unattended allergic reactions can be life-threatening and fatal.

When to Consult a Doctor?

The following is a list of food allergy symptoms that may need immediate medical attention:

• Difficulty breathing or swelling of the face, lips, or throat
• Dizziness, fainting, or feeling very weak
• Repeated allergic reactions after eating the same food
• Severe digestive symptoms like vomiting, diarrhoea, abdominal pain
• Tightness in the chest
• Chronic skin rashes or itching
• Loss of consciousness and BP fall¹

Conclusion

Food allergies can range from mild discomfort to serious, life-threatening reactions, so it is important to take them seriously. Recognising symptoms early and avoiding trigger foods can help avoid the complications. If you notice any unusual reactions after eating, do not ignore them and seek medical advice. With proper care and awareness, food allergies can be managed safely.

Also Read: Drug Allergy: Symptoms, Causes, Diagnosis, Tests & Treatment

Frequently Asked Questions (FAQs)

References

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