How to distinguish between allergic and non-allergic skin rashes: when to consult an allergist or immunologist

• Overview
• Allergic and non-allergic skin rashes
• Comparison
• Which diagnostic method is better?
• Professional diagnosis
• Summary

Skin Rashes: An Overview

Skin rashes are a common dermatological condition that affects people worldwide. Accordibg to a study from USA, every person has 1.6 skin rashes per year ¹. Skin rashes may present symptoms of any perceptible change in skin appearance, texture, or color. They can develop on any part of the body and there are various forms, including itchiness, mild red spots, bumps, blisters, moles, or scaly patches. Skin rashes can be caused by a variety of factors, including allergies, infections, medications, autoimmune diseases, and environmental irritants. They may also be a symptom of an underlying medical condition or a reaction to certain foods or chemicals.

There are allergic and non-allergic skin rashes. They have some differences in terms of their causes, symptoms, and treatment. It is important to distinguish between allergic and non-allergic skin rashes for proper diagnosis and management of skin rashes. Hence, it can help to determine the cause of the rash and provide appropriate treatment options.

By reading the entire content you will get a brief idea of allergic and non-allergic skin rashes, distinguish between the causes and symptoms, and get a clear idea of diagnostic methods for such rashes. You will get an idea about the condition at which you should consult an allergist or immunologist and how you can find such a medical provider in-person or online.

Allergic and non-allergic skin rashes

Allergic skin rashes

Allergic skin rashes are caused by an immune system response to an allergen, which can be a substance that the body perceives as harmful to some people, even though it is harmless to most people. The immune system of the person who comes into contact with the allergen produces an antibody called immunoglobulin E, which triggers the release of histamine and other chemicals that cause inflammation and itching in the skin.

Common allergens that can cause skin rashes are,

1. Plants: The plants such as poison ivy, poison oak, and poison sumac contain an oil called urushiol, which can cause an allergic reaction in most people who come in contact with it.
2. Cosmetics: Certain ingredients in cosmetics such as fragrances, preservatives, and dyes can cause allergic skin reactions.
3. Metals: Some people may develop an allergic reaction to metals such as nickel, which is commonly found in jewelry, clothing fasteners, and other metal items.
4. Medications: Certain medications such as antibiotics, anti-inflammatory drugs, and anticonvulsants can cause allergic skin reactions in some people.
5. Foods: Certain foods such as peanuts, tree nuts (such as almonds, walnuts, and cashews), seafood (such as shellfish, shrimp, crab, and lobster), eggs, milk, soy, and wheat can cause allergic skin reactions in some people.
6. Insect bites: When certain insects such as mosquitoes, bees, wasps, hornets, and fire ants bite or sting, hypersensitivity reactions may take place causing skin allergies.

Examples of allergic skin rashes include:

1. Contact dermatitis: This is a common allergic skin reaction that occurs when the skin comes into contact with an allergen or irritant. Contact dermatitis is divided into irritant contact dermatitis and allergic contact dermatitis. Irritant contact dermatitis is a nonspecific response of the skin to direct chemical damage that releases mediators of inflammation predominantly from epidermal cells while allergic contact dermatitis is a delayed (type 4) hypersensitivity reaction to exogenous contact antigens ². Symptoms include redness, swelling, itching, and sometimes blistering or oozing.
2. Hives: Hives are raised, itchy, and red bumps on the skin that can appear suddenly and disappear quickly. They are often caused by an allergic reaction to food, medication, or other allergens.
3. Atopic dermatitis (eczema): This is a chronic, itchy skin condition that is often associated with allergies and asthma. It can cause red, scaly patches on the skin.
4. Angioedema: This is a type of allergic reaction that causes swelling in the deeper layers of the skin. It can be triggered by certain medications, foods, or insect bites.

Non-allergic skin rashes

Non-allergic skin rashes are skin conditions that are not caused by an allergic reaction. They can be caused by a variety of factors.

Common causes of non-allergic skin rashes are,

1. Infections: Viral, bacterial, and fungal infections can cause a wide variety of skin rashes such as chickenpox, shingles, impetigo, ringworm, and athlete’s foot.
2. Autoimmune disorders: Conditions such as lupus, psoriasis, and scleroderma can cause chronic skin rashes.
3. Medication reactions: Some medications can cause skin rashes as a side effect. This is often a result of an interaction between the medication and the body’s immune system.
4. Physical irritants: Certain substances and conditions can irritate the skin and cause a rash. Examples include harsh soaps, detergents, and fabrics, as well as extreme temperatures and sun exposure.

Examples of non-allergic skin rashes include:

1. Psoriasis: A chronic autoimmune disorder that causes red, scaly patches on the skin. The causes may include genetic factors and environmental factors.
2. Rosacea: A chronic skin condition that causes redness, flushing, and acne-like bumps on the face. This may be related to genetic and environmental factors.
3. Heat rash: A rash that occurs when sweat ducts become blocked, causing small red bumps on the skin.
4. Seborrheic dermatitis: A common skin condition that causes red, scaly patches on the scalp, face, and other areas of the body. The causes for this condition are thought to be related to an overgrowth of a type of yeast called Malassezia. Hormonal changes, stress, and neurological disorders may also play a role.
5. Tinea infections: Fungal infections that can cause ringworm, jock itch, and athlete’s foot, among other skin conditions.
6. Impetigo: A contagious bacterial infection that causes red, itchy, and oozing blisters on the skin.
7. Hives: A skin rash characterized by raised, itchy, and often red welts on the skin that can be triggered by a variety of factors other than allergies including stress, and infections.

Comparison of allergic and non-allergic skin rashes

Allergic skin rashes and non-allergic skin rashes have differences in appearance, symptoms, and causes.

Differences in appearance:

• Allergic skin rashes are often characterized by redness, itching, and swelling of the skin. They may appear as raised bumps, blisters, or hives. Hives may also be raised and have a pale center.
• Non-allergic skin rashes may appear as dry, scaly patches of skin, or as red, inflamed areas. They may be accompanied by itching, burning, or stinging sensations. It can be often painful.

Differences in symptoms:

• Allergic skin rashes are typically accompanied by other allergy symptoms such as sneezing, a runny nose, or watery eyes. They may also be accompanied by other systemic symptoms such as fever or difficulty breathing.
• Non-allergic skin rashes are not usually accompanied by other allergy symptoms; but may cause discomfort, itching, or pain in the affected area.

Differences in causes:

• Allergic skin rashes are caused by an immune response to an allergen, which can include a wide range of allergens such as foods, medications, or environmental triggers like pollen or pet dander, insect bites or stings, exposure to certain metals such as nickel, and by the usage of certain cosmetics.
• Non-allergic skin rashes can be caused by a variety of factors such as infections, autoimmune disorders, genetic factors, medication reactions, and physical irritants like harsh soaps or extreme temperatures.

It’s important to note that some skin rashes can have causes of both allergic and non-allergic skin rashes. For example, a person may have an allergic reaction to a certain medication; but also develop a non-allergic rash from prolonged sun exposure or fungal infection.

Which diagnostic method is better? Self-diagnosis or professional diagnosis?

It is not recommended to rely solely on self-diagnosis for skin rashes, as many skin conditions can have similar symptoms but require different treatments. It is important to seek professional diagnosis and treatment from a healthcare provider who can properly evaluate the rash and determine the underlying cause of the rash.

Self-diagnosis of skin rashes, whether allergic or non-allergic, can carry several risks. They are,

1. Misdiagnosis: Skin rashes can have similar symptoms but different underlying causes, and misdiagnosis can lead to inappropriate treatment or delay in proper treatment. For example, a person with an allergic skin rash may mistakenly believe it is a non-allergic rash and continue to be exposed to the allergen, leading to more severe symptoms.
2. Delay in treatment: A delay in seeking professional diagnosis and treatment can allow a skin condition to worsen and potentially lead to complications. For example, a person with a non-allergic skin rash may delay seeking medical attention, allowing a bacterial infection to develop and spread.
3. Inappropriate treatment: Self-diagnosis can lead to inappropriate treatment, such as using over-the-counter medications that may be ineffective or harmful for the particular type of rash. For example, using a topical steroid cream on an infectious rash can worsen the infection.
4. Failure to recognize underlying conditions: Some skin rashes can be a symptom of a more serious underlying condition, such as lupus or certain types of cancer. Failure to recognize these underlying conditions can delay proper diagnosis and treatment.

It is important to seek professional diagnosis and treatment from a healthcare provider. Seeking professional diagnosis for allergic and non-allergic skin rashes has several advantages. They are,

1. Accurate identification of the cause of the rash: A healthcare provider can perform a physical exam and possibly diagnostic tests to accurately identify the underlying cause of the rash. This can help differentiate between different types of rashes, including allergic and non-allergic rashes, and ensure appropriate treatment.
2. Appropriate treatment: A healthcare provider can provide appropriate treatment based on the underlying cause of the rash. This can include prescription medications, topical treatments, or lifestyle modifications, depending on the type and severity of the rash. In addition, a healthcare provider can monitor the progress of treatment and adjust it as necessary.
3. Prevention of complications: Professional diagnosis and treatment can prevent potential complications from skin rashes. For example, a healthcare provider can treat an infectious rash with antibiotics to prevent the infection from spreading to other parts of the body.
4. Recognition of underlying conditions: Some skin rashes can be a symptom of an underlying condition, such as lupus or diabetes. A healthcare provider can recognize these underlying conditions and provide appropriate referrals for further evaluation and treatment.

Professional diagnosis of allergic and non-allergic skin rashes

Whom should you consult?

When you experience symptoms of allergic or non-allergic skin rashes, it is always advisable to consult professionals such as allergists or immunologists who can accurately diagnose the skin condition. He/she will be a certified subspecialist in allergy and immunology ³.

Role of allergist or immunologist in diagnosing allergic and non-allergic skin rashes:

An allergist or immunologist is a medical professional who specializes in diagnosing and treating conditions related to the immune system, including allergic and non-allergic skin rashes.

In diagnosing skin rashes, an allergist or immunologist will typically start by performing a physical exam and taking a medical history. This may involve asking questions about the duration and severity of the rash, any known allergens or irritants that may be causing the rash, and any other symptoms that the patient may be experiencing.

Based on the initial assessment, the allergist or immunologist may then perform additional tests to help identify the underlying cause of the rash. These tests may include:

• Skin prick tests: A skin prick test involves exposing the skin to small amounts of common allergens to see if a reaction occurs.
• Patch tests: A patch test involves applying small amounts of common allergens to the skin and then monitoring for any signs of an allergic reaction.
• Blood tests: Blood tests can help identify specific allergens or antibodies in the blood that may be contributing to the rash. Some common blood tests include complete blood count (CBC), specific immunoglobulin E (IgE) blood test, autoimmune markers test, inflammatory markers test, and viral serology.
• Skin biopsies: In some cases, a skin biopsy may be performed to examine a small sample of skin tissue under a microscope to help identify the underlying cause of the rash.

Once the underlying cause of the rash has been identified, the allergist or immunologist can then provide appropriate treatment recommendations. This may include avoiding known allergens or irritants, using topical or oral medications to manage symptoms, or undergoing immunotherapy to help desensitize the immune system to specific allergens.

Signs of allergic and non-allergic skin rashes that you may need to consult an allergist or immunologist:

Signs of allergic skin rashes that may require consultation with an allergist or immunologist include:

• Allergic skin rashes accompanied by intense itching or a burning sensation.
• Redness and swelling which may occur in localized areas or across a larger part of the body.
• Raised, itchy welts on the skin appear suddenly and can be a sign of an allergic reaction.
• Fluid-filled blisters Formed on the skin.
• A rash that spreads quickly over a large area of skin.
• Other symptoms, such as difficulty breathing, wheezing, or swelling of the face or throat, can be serious and require immediate medical attention.

Signs of non-allergic skin rashes that may require consultation with an allergist or immunologist include:

• Persistent or worsening symptoms: If a skin rash does not improve or worsens over time, it may be a sign of an underlying condition that requires medical attention.
• Difficulty identifying the cause of the rash: Some skin rashes can be difficult to diagnose, and an allergist or immunologist may be able to help identify the cause of the rash and recommend the appropriate treatment.
• Previous history of allergies or allergic reactions: People with a history of allergies or allergic reactions may be at higher risk of developing skin rashes, and may benefit from a consultation with an allergist or immunologist.

How can you find an allergist or immunologist?

1. Ask your primary care doctor for a referral: Your primary care doctor whom you consult may be able to recommend an allergist or immunologist in your area.
2. Check with your health insurance provider: Many health insurance plans have a list of approved specialists, including allergists and immunologists. Check your insurance provider’s website or call their customer service line to find a specialist covered by your plan.
3. Use online directories: There are several online directories that can help you find allergists or immunologists in your area. Ask for recommendations: Ask family members, friends, or colleagues who have had similar symptoms or conditions for recommendations for allergists or immunologists.
4. Online resources: Once you have a list of potential allergists or immunologists, do some research to learn more about their qualifications, experience, and patient reviews. You can use online resources such as online dermatology sites to help with your research.

How can you seek professional advice in the diagnosis and treatment of allergic and non-allergic skin rashes?

To seek professional advice for allergic or non-allergic skin rashes, individuals can start by scheduling an appointment with a healthcare provider, such as a dermatologist. During the appointment, the healthcare provider will perform a physical examination of the affected area and may ask questions about medical history and lifestyle factors that may be contributing to the rash. In some cases, the healthcare provider may also perform diagnostic tests, such as skin allergy testing or skin biopsies, to help determine the underlying cause of the rash.

In addition to in-person appointments, there are also online dermatologists who can provide professional consultations for skin rashes. Online dermatologists work by using telemedicine technology to connect with patients remotely, typically through a video chat or messaging platform. Patients can provide pictures or descriptions of their skin rash to the online dermatologist, who can then make a diagnosis and provide treatment recommendations.

Online dermatologists can be a convenient and accessible option for individuals who may have difficulty accessing in-person healthcare, such as those who live in remote areas or have mobility or transportation issues. However, it is important to choose a reputable online dermatology service that employs licensed healthcare providers and follows standard practices for diagnosis and treatment.

It is important to note that some skin rashes may require an in-person evaluation and diagnostic testing for accurate diagnosis and treatment. In these cases, an online dermatologist may recommend that the patient seek in-person care.

Summary

Skin rashes can appear due to allergic conditions or non-allergic conditions. Allergic skin rashes are caused by an immune response to allergens such as certain plants, cosmetics, metals, medications, food, and insect bites. Non-allergic skin rashes are caused by infections, autoimmune disorders, medication reactions, and physical irritants. Both allergic and non-allergic skin rashes differ in their appearance, symptoms, and causes.

It is better to seek professional diagnosis and treatment methods rather than relying on self-diagnosis; since it can help in accurate identification, provide appropriate treatment, and prevent complications. It is advisable to consult an allergist or immunologist for diagnosis and treatment purposes.

You can seek in-person medical care or consult an online dermatologist. If you are hesitant to seek help due to concerns about in-person appointments or access to healthcare, know that many healthcare providers now offer telemedicine options, including online dermatologists. Online dermatologists can provide professional consultation, diagnose skin rashes, and recommend appropriate treatment plans. Don’t let fear or uncertainty prevent you from seeking the help you need. Seeking professional help for skin rashes can provide peace of mind and help prevent potential complications.

References:

1. Henry W. Lim MD a, Scott A.B. Collins MD b, Jack S. Resneck Jr. MD c, Jean L. Bolognia MD d, Julie A. Hodge MD, MPH e, Thomas A. Rohrer MD f, Marta J. Van Beek MD, MPH g, David J. Margolis MD, PhD h, Arthur J. Sober MD i, Martin A. Weinstock MD, PhD j, David R. Nerenz PhD k, Wendy Smith Begolka MBS l, Jose V. Moyano PhD, The burden of skin disease in the United States, https://doi.org/10.1016/j.jaad.2016.12.043
2. Graham Litchman; Pragya A. Nair; Amber R. Atwater; Beenish S. Bhutta, Contact Dermatitis, National Library of Medicine, https://www.ncbi.nlm.nih.gov/books/NBK459230/
3. Philip Fireman, MD, Chairman, N.Franklin Adkinson, MD, J.Spencer Atwater, MD, Mark Ballow, MD, Stephen I. Wasserman, MD, Role of the allergist/immunologist as a subspecialist, https://www.jacionline.org/article/S0091-6749(97)70238-0/fulltext#%20