The skin is made up of millions of tiny cells joined together to form a protective outer layer. As a living organ, it grows, regenerates, adapts and responds to damage and insults triggered by a wide range of internal and external factors. Common skin conditions, namely, dry skin (eczema, xerosis and psoriasis) and itch (pruritus) are predominantly related to the dysfunction of the skin’s components and functions or defects found in the different structural layers (especially in the outer layer = epidermis) of skin. Dry skin is mainly characterised by the lacking of natural oils (sebum) as well as by lacking of water and moisture in general. Regardless of age, gender and race, many people are affected by dry skin conditions and itch, which include not only the people who suffer from it but also those who manage it. It can be physically and emotionally traumatic, equally, for both sufferers and their families.
What are dry skin conditions and what causes them?
Maintaining the skin’s function as a protective barrier and stopping irritants and allergens from entering the body is equally important to preventing the loss of crucial moisture from the skin to the outside world. If the skin barrier is not working properly, this can lead to the development or worsening of many dry skin conditions namely, eczema, xerosis, psoriasis as well as itch (pruritus) related conditions, affecting different body areas/parts with a various degree of severity.
Unlike the smooth, soft and healthy appearance of normal skin, dry skin lacks moisture, has a rough texture due to an imbalance and/or insufficiency of skin oils and may be scaly, flaky and prone to forming shallow cracks and can feel uncomfortable and itchy. While some people are born with a natural tendency towards dry skin those suffering from other health conditions such as asthma, hay fever or allergies may also develop dry skin.
Dry skin is often the result of a combination of genetic abnormalities, but also metabolic and environmental triggers (for example, excessive bathing and washing, excessive use of harsh, fragrant soaps and strong detergents, and frequent exposure to extreme weather conditions). Also, as we age, our bodies produce less sebum, naturally produced by the skin that helps to keep skin smooth and supple, leading to naturally drier skin.
In simple dermatology terms, eczema (also known as atopic dermatitis), as well as being incurable, is the most prevalent chronic (long-term) inflammatory skin condition in the world that can affect up to 3% of adults and 20% of children. While it can last into adulthood in some instances, many cases may improve or clear during childhood. The most common symptoms are intense and persistent itch and red, inflamed, dry and scaly skin in areas such as the joints.
The cause of eczema is not well known, however, it seems to result from a combination of (1) genetic, (2) immune and (3) environmental factors:
(1) Genetic factors: Children are more likely to develop eczema if a parent has had it or conditions like asthma or hay fever. If both parents have any of these three conditions, the likelihood increases.
(2) Immune factors: Eczema is also associated with malfunction and imbalance of the body’s immune system that can create inflammation (flares) in the skin.
(3) Environmental factors: There are many environmental factors that can either trigger or worsen eczema such as use of personal care products (soaps, detergents and fragrances); environmental allergens such as pollen; environmental stressors such as humidity and extreme temperatures; food intolerances and common skin irritants such as wool and synthetic fibers.
The basic characteristic of xerosis is the presence of dry, rough and scaly skin that has lost its normal properties and look due to the dehydration of the outermost layer of epidermis (stratum corneum) that is unable to retain water and loses moisture faster than it is replenished. A decline in natural oil (lipid) content gives rise to an increase in insensible water loss, which in turn destabilises the optimum environment for skin’s structure and function. This change inhibits the natural cycle of skin cell’s regeneration and shedding/peeling. This in turn further aggravates the disturbance of the stratum corneum and completes the self-perpetuating skin damage cycle. If not treated timely and appropriately, severe xerosis can lead to the onset of a type of eczema characterised by intensely itchy and cracked skin.
Psoriasis is a relapsing, long-term inflammatory skin disease with a strong genetic predisposition and autoimmune pathogenic traits. The worldwide prevalence is about 2-5%, but varies according to regions. In this disease, the skin keeps flaking and scaling, continuously producing psoriatic plaques due to rapid and excessive generation of epidermal cells which look like fishy skin that finally peels off.
What is itch and what causes itchy skin?
Itch (also known as pruritus) is defined as an unpleasant skin sensation which provokes the desire to scratch and is usually described as a continual and widespread scaling of the skin that affects the whole body. Itch can lead patients to scratch until they are bleeding, and scratching in turn can aggravate skin disease. Most types of itchy skin conditions are congenital, meaning that they are present at birth, and inherited, meaning that they result from genetic changes, so they may run in families. Itch is caused by mutations in genes that control the formation of skin cells, so they do not function properly. In some forms of itch, skin cells are formed at a faster rate than they are needed and they pile up on the skin surface, thickening the skin and making it dry. In other forms, the cells are produced at the normal rate but instead of shedding when they reach the surface, they cannot become detached from the cells beneath them and so they build up in layers.