Eczema Causes

What is eczema?

Eczema or atopic dermatitis is an inflammatory condition of the skin characterized by redness, itching, dryness, and rash. It typically starts in early childhood, before the age of two, but can also affect adults. Eczema is the most common skin condition in children.1

Inflammation is the response of the body’s immune system to external harmful stimuli such as bacteria, viruses, toxins, foreign substances, etc. With eczema, the body’s immune system reacts to different substances in the environment producing an allergic reaction resulting in inflammation of the skin and manifestation of other symptoms.

Eczema is a chronic relapsing condition, where symptoms can be of varying degrees of severity at different stages of life. Those that have eczema are more likely to develop other atopic (allergic) conditions, such as environmental and food allergies, asthma, and allergic rhinitis.

Symptoms of eczema

The following are the common symptoms of eczema:

  • Itching - the most common and causes immense discomfort to the person
  • Redness
  • Papules – a raised area of skin tissue, usually seen in one-year-olds
  • Patches – discolouration of the skin, seen in children 
  • Plaques – raised thick shiny lesions
  • Scaly rash 
  • Bleeding – usually occurs because of excessive scratching 
  • Oozing clear fluid from the rash site
  • Dry flaky skin
  • Skin thickening 

Location of Eczema Rash and Symptoms 

Eczema can affect any part of the body. The common sites affected by eczema differ according to the age groups:

  1. One-year-olds – face (especially the cheeks), scalp, trunk, and extremities (arms and legs). 
  2. Older children – flexural surfaces (that is the skin where your joints bend). For example, inside your elbows, behind your knees, and in the neck folds. 
  3. Adults – extremities (arms and legs).1

Phases of Eczema

Eczema symptoms are recurrent in their appearance. There are periods when the symptoms are not detectable, as well as periods when the symptoms are extremely severe (flare-ups).  

  1. Acute Phase (severe, short duration)  – In this phase, there are multiple small fluid-filled sacs (vesicles) that can rupture or ooze clear fluid (weeping). This fluid can also collect and dry on the surface of the skin (crusting).
  1. Subacute Phase (condition between acute and chronic, moderate intensity) – In this phase, there are multiple dry, scaly, red papules (raised area of skin tissue, less than 1cm) and plaques (raised thick shiny lesions, more than 1cm) on the skin.
  1. Chronic Phase (persistent, long-standing) – Due to repeated scratching and rubbing of the skin, it becomes thickened. This is also called lichenification, where the skin is hyper-pigmented (darker in colour than usual), thick, and leather-like.2

Excessive rubbing or scratching can result in the excoriation of the skin and the development of secondary infections.

Eczema Causes vs. Triggers

The exact cause of eczema or atopic dermatitis is not clearly known. It is likely to be caused by a combination of multiple factors, including genetics, a hypersensitive immune system, and environmental factors that result in disruption of the normal skin barrier. This makes the skin of people with eczema more sensitive to certain triggers in the environment. Any contact with these triggers can cause symptoms like itching, redness, etc., to appear.

Causes of Eczema

Family History of Eczema

Children who have one parent or both parents or a sibling with eczema are more likely to develop it themselves as well. It also occurs in people who have other allergic conditions and can develop alongside other conditions, such as asthma and allergic rhinitis. 70% of people who suffer from eczema have a strong family history of allergies.3

Dysfunctional Skin Barrier

The skin is made up of multiple layers of cells and tissues that prevent water loss from the body, retain moisture in the skin and form a protective barrier against foreign substances like microbes (bacteria and viruses) and allergens (substances that cause an allergic reaction of the immune system).

In people with eczema, this barrier is compromised because of a special gene mutation. The skin is not able to retain moisture and is dry, making it more likely to react to certain triggers. Allergens such as pollens, house dust mites, certain foods, microbes, and irritants penetrate the skin when the barrier is dysfunctional to trigger an exaggerated immune response.

Immune System Dysfunction:

IgE is a special type of antibody produced by the immune system in allergic reactions. When you come in contact with anything that you are allergic to, the body produces these antibodies that cause the release of chemicals. This is an exaggerated reaction of the immune system that can also lead to damage.

The cells of the immune system, called T-helper type 2 cells, increase the production of IgE, while T-helper type 1 cells suppress the production of IgE.

People who have eczema have an increased number of T-helper type 2 cells in their bodies that make them more susceptible to having exaggerated responses to triggers in the environment.2

How does the immune system cause eczema?

People with eczema have a genetic makeup that renders their immune system sensitive. Whenever their skin comes in contact with any trigger in the environment, such as pollens, dust mites, irritants in soaps and shampoos, etc., their immune system reacts in an exaggerated manner causing damage and inflammation of the skin. 

Triggers of Eczema

Triggers are irritants in the environment that causes an exacerbation of eczema symptoms. Avoiding these triggers can help control disease activity and limit the symptoms. Some of the common triggers of eczema are:

  • Environmental triggers – things in the environment like pollens, dust, house mites, moulds, pet fur, and cigarette smoke.
  • Irritants – skin irritants like fragrances in cosmetics, some soaps and detergents, and shampoos.
  • Food allergens – these commonly act as triggers in infancy. Some of these foods include eggs, peanuts, soy, milk, wheat, tree nuts, fish, and shellfish.
  • Temperature changes: extremes of temperature can worsen eczema.
    •  Cold weather can cause dryness of the skin.
    •  Hot weather causes excessive sweating and worsens itching.
  • Skin infections – mostly viral infections.
  • Clothing of certain materials – synthetic fibre and wool (in early childhood).
  • Stress – emotional stress can worsen itching.

Conclusion

Eczema, or atopic dermatitis, is the most common skin condition in children. It is characterised by an exaggerated immune response of the body to different environmental factors resulting in inflammation of the skin. 

The symptoms of eczema are intense and troublesome itching, redness, and rash. The rashes can further be complicated by repeated scratching leading to thickening of the skin, excoriation, scarring, and infections.

Genetic dysfunction of the normal skin barrier combined with a hypersensitive immune system causes eczema. Environmental factors such as pollen, house dust mites, cigarette smoke, extremes of weather, and certain foods can trigger the immune system and cause a flare-up of the symptoms. Avoiding these triggers can help control the disease. 

References

  1. Frazier W, Bhardwaj N. Atopic Dermatitis: Diagnosis and Treatment. Am Fam Physician. 2020; 101(10):590–8.
  2. Berke R, Singh A, Guralnick M. Atopic dermatitis: an overview. Am Fam Physician. 2012; 86(1):35–42.
  3. Avena-Woods C. Overview of atopic dermatitis. Am J Manag Care. 2017; 23(8 Suppl):S115–23.

Aatika Owais

Bachelor of Medicine & Bachelor of Surgery (MBBS); Dow University of Health Sciences, Karachi, Pakistan

Dr. Aatika is a junior doctor, with an avid interest in surgery and clinical research, having hospital experience complimented with excellent patient management skills.
She has experience in writing research articles and peer-reviewing articles for medical journals.
She is registered with Pakistan Medical Council and with the General Medical Council, UK as a fully licensed doctor. She is an aspiring neurosurgeon and believes in utilizing research to uncover new therapies and procedures to deliver high-caliber patient care.

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