Why do we have dry skin?

An insufficient sebum production is the primary cause of skin dryness. It results from both internal and external factors.

• Hereditary.

  In some individuals, skin dryness is due to a genetic predisposition. Indeed, a mutation on the gene coding for the filaggrin protein is often responsible. This protein is normally expressed in epidermal cells and helps to maintain the skin barrier function.

• Hormonal fluctuations.

  Sebum production is also influenced by hormonal factors. Thus, it is possible for the skin to become dry during puberty, pregnancy or menopause, periods when significant hormonal variations occur. Indeed, female sex hormones, the oestrogen and progesterone, are closely linked to ageing and skin dryness. Oestrogens notably have the effect of stimulating the synthesis of collagen and elastin by fibroblasts, structural proteins of the epidermis. As for progesterone, it stimulates the production of sebum by the sebaceous glands, which promotes the maintenance of the skin's hydrolipidic film. At menopause for example, the synthesis of oestrogen and progesterone by the ovaries is halted. This causes a decrease in sebum production, and thus a weakening of the hydrolipidic film. The skin is then more exposed to skin dryness.

• Some skin conditions.

  The psoriasis or eczema can also be responsible for skin dryness. These chronic inflammatory diseases often manifest themselves through the appearance of red patches and skin dryness. The causes of these conditions remain largely unknown, but it appears that the risk factors are primarily of two types: genetic and infectious.

• The natural ageingprocess.

  The skin's ability to produce sebum decreases with age. Indeed, the activity of the sebaceous glands weakens in our thirties, which compromises the hydrolipidic film. The synthesis of ceramides also begins to decline, impacting the skin barrier. Additionally, the level of hyaluronic acid also gradually decreases, starting as early as our twenties. This molecule plays a key role in skin hydration and is notably capable of retaining up to 1,000 times its weight in water.

• Some environmental factors.

  External factors can also contribute to skin dryness. Prolonged exposure to the sun or to dry and freezing air during winter can weaken the epidermis. These elements can lead to the degradation of the hydrolipidic film that protects the skin. This film tends to thin out and can no longer perform its function properly.

• The use of unsuitable products.

  When one has dry skin, it is recommended to favour gentle, nourishing and lipid-replenishing treatments, and to avoid any product containing matifying active ingredients such as zinc or azelaic acid. The use of alcohol derivatives and synthetic fragrances is also discouraged, as these products are drying.

• Hard water.

  After a shower with hard water, feelings of skin tightness may occur, accompanied by various issues such as irritations, itching, or even the appearance of red patches. The explanation is as follows: the calcium and magnesium ions, which make up the hardness of the water, form microcrystals on the skin, causing the prickling sensations.