Overview

Skin rashes are characterized by change in color, feeling or texture of the skin,¹ and many of them are presented as itchy, red, painful and irritated.²

They are usually brought about by many factors,² for instance; skin infections, allergies, medication, etc. For that reason, it’s necessary to figure out the actual cause of the skin rash before treatment, by assessing appearance, location, symptoms or by performing specified skin testing.¹

Among the several causes of skin rash, one of them is food allergies,³ whose prevalence is rising, similar to all allergic diseases. Allergies are developed when the immune system mistakenly responds to food as if it were harmful,⁴ with some of the common food allergens including: milk, eggs, peanuts, tree nuts, fish, shellfish and some fruits.⁵

Risk Factors Of Food Allergies

For someone to develop one  of these food allergies, chances are they were  exposed to one or more risk factors, namely;

• If you had allergies in childhood, they are more likely to persist into adulthood⁶
• Early onset of atopic dermatitis (eczema) poses a risk of food allergy development⁵
• If a family member has either asthma, eczema or food allergy, there's a high likelihood of you developing some form of food allergy⁶

Types Of Food Allergies And Their Effect On Skin

These food related reactions could start within minutes, or take up to two to six hours for delayed reactions,⁷ with varying severity for different individuals. They are dependent on the type of allergy presented, which could either be;

Immunoglobulin E-mediated (igE) food allergy

Symptoms occur within a few seconds or minutes after eating and is the most common type of allergy. 

It’s also what triggers histamine production - a chemical released during an immune response - which contributes to some of the skins’ allergic symptoms by;

• Affecting nerves on the skin, prompting itchiness⁵
• Causing expansion of nerve vessels leading to swelling and reddening of surrounding skin⁵

Non-immunoglobulin E-mediated (non-igE) food allergy

Caused by other cells in the immune system and not immunoglobulin. Symptoms take longer to develop, but when they do, they include skin conditions like eczema, where approximately 40% of individuals with food allergies also develop chronic atopic dermatitis (eczema).⁸

In addition to contact dermatitis, eczema and hives are two of the most common types of skin rashes related to food allergies.⁹

Hives (Urticaria)

Also referred to as Urticaria, this skin condition is triggered by foods like eggs, peanuts, nuts and shellfish,¹⁰ and is majorly characterized by an itchy rash that is raised, patched,¹¹ and red or skin-colored, that could appear anywhere on the body.¹⁰

Hives sometimes occur concurrently with angioedema,¹² and even get mistaken for it. Angioedema is characterized by swelling in the eyes, mouth, hands, feet or throat, and may become a medical emergency depending on the severity of swelling.

The symptoms of hives could be short-lived  (active hives) or last longer   (chronic hives), occurring almost daily for more than six weeks, which will necessitate you to see a professional for cause analysis.¹⁰

After which, management will involve itch relief, use of immunity modifiers like antihistamines, and after the trigger is identified, you'll be advised to completely avoid and eliminate it.¹⁰

Eczema (Atopic Dermatitis)

This condition, also known as atopic dermatitis, is characterized by long-term inflammation, itchy, irritated, cracked, swollen and red skin.¹³

Its onset is usually in children below three years of age and could have relapse episodes throughout the following years, possibly even into adulthood.

It's brought about by hereditary factors especially if either parent has history of atopic dermatitis, diet of high polyunsaturated fatty acids and sugars,¹³ and environmental factors such as extreme temperatures, microbes, irritants and psychological stress.¹⁴

According to a hypothesis, early onset atopic dermatitis (eczema) increases the chances of food allergies development by creating a dysfunctional skin barrier that allows food allergens to reach immune cells more easily, hence activating biological processes that cause food allergies and other comorbidities such as asthma.¹⁵

The most common food allergy triggers for those with eczema include: chicken eggs, milk, soy, fish, wheat, peanuts and tree nuts.¹³

While it has no cure, most children tend to outgrow the skin condition past puberty, but sometimes it still persists into adulthood. When active, symptoms can only be managed  by topical or non-topical treatments to help restore the skin barrier, reduce inflammation and improve the quality of life.¹³

These treatments and possible preventive measures include:

• Emollients and topical corticosteroid application even when there's no flare to reduce the incidence of food allergies
• Bathing with soap replacements with specific ingredients shown to be gentle to eczema
• Avoiding triggers such as food allergens, wool and synthetic materials, extreme temperatures and humidity, etc
• Supplementation with Vitamin D especially for those with low levels to alleviate the symptoms like skin irritation¹³

Systemic Contact Dermatitis

This is an allergic immunological reaction that occurs after allergen exposure via different routes in addition to oral ingestion.

It could occur through inhalation, intravenous or intramuscular administration of certain dietary allergens, with the most common triggers being BOP (Balsam of Peru) and nickel.¹⁶ 

While atopic contact dermatitis occurs from external exposure to allergens leading to localized inflammatory response, systemic contact dermatitis could either be localized or widespread.¹⁶

Major allergens related to BOP include: citrus fruits, tomatoes and spices such as cinnamon, vanilla/vanillin and cloves.¹⁶

Nickel on the other hand, involves dietary nickel that results in acute vesicular hand dermatitis. This could be from wheat bread, oatmeal, soy products, beans, lentils, peas, nuts, seeds, canned foods, black tea, etc.¹⁶ All vary in contents depending on local soil conditions and use of fungicides.¹⁷ 

Improvement from allergic reactions may require avoidance of triggers for 6 to 8 weeks.¹⁶

Other potential food allergens include: propylene glycol common in commercially prepared food items such as barbecue sauce, food colorings and salad dressings; chamomile which has the allergen sesquiterpene lactones,¹⁸ and formaldehyde from the artificial sweetener aspartame which has previously triggered eyelid dermatitis.¹⁹

Considerations To Make When Dealing With Food Allergies

1. Food Elimination Diets

While food elimination might be necessary to deal with particular allergies, there is an underlying risk of nutritional deficiencies which would later affect growth, development and a potential occurrence of anaphylaxis²⁰ after uncontrolled reintroduction of the eliminated food.¹⁴

This is only advised when there's documented food allergies, to act as evidence of direct correlation with the condition in question capable of reducing symptoms occurrence.¹⁴

It is therefore advised that parents give complementary foods rich in similar nutrients to help counter the nutritional deficiencies risk, and reintroduce restricted foods after 12-24 months.¹⁴

2. Proper Food Allergy Diagnosis

A positive skin-prick test, patch test or allergen-specific serum immunoglobulin E test alone, cannot diagnose food allergy as they identify sensitization to specific foods. Proper food allergy diagnosis involves both sensitization and specific clinical symptoms upon exposure to food, best done by the double-blind, placebo-controlled food challenge.¹⁴

Allergy Management And Prevention Strategies 

While the best way to manage any allergic reaction is by avoiding the particular food trigger, below methods can also come in handy:

1. Early Introduction Of Food Allergens

In a study sponsored by NIAD, participants who regularly consumed peanut from infancy had reduced likelihood of getting peanut allergies in adolescence by 71%.²¹ It's also recommended to introduce complementary allergenic solid foods one at a time, four to six months of age when breastfeeding.⁸

2. Diet And Treatment Tracking

In the event of a reaction, journaling what you eat, what helps to manage symptoms, causes and what worsens your allergic reactions can help to prevent recurrence.²²

3. Allergen Declaration

The Food Standards Agency requires food businesses to provide allergen information, follow labeling rules and handle food allergens effectively to prevent cross-contamination.²³

Consumers on the other hand need to be cautious enough to always go through food labels and practice proper handling during preparation, to avoid last minute cross-contamination or even contact reactions.

4. Education On Allergy Management

Children and caregivers need extensive education on matters of allergy management. This involves  reading and understanding food labels, checking restaurant meals, being keen on symptoms and being confident in  using relief options and medication.³

5. Emergency Preparedness 

Patients with food allergies and a history of severe reactions should be given antihistamines, self-injectable epinephrine and a written emergency plan for unintended allergen contact or ingestion.³

Conclusion

With the rising prevalence of food allergies, it is necessary to learn and understand, as much as possible, the implications of its symptoms. 

With skin rashes being our point of interest and one of the early identifiers of potentially severe reactions, comprehensive knowledge detailing the different types, risk factors, triggers, and ways of managing them will help promote better prevention and management strategies, prompting well informed dietary and lifestyle choices.

This will not only ensure good health and safety, but also sustain the quality of life for all affected individuals.