Hyperpigmentation and skin whitening

Melanocytes are very sensitive cells. Some scientists even believe that melanocytes act as a sentry post that reacts to all negative influences. The main stimulus for melanocytes is UV radiation, but melanin synthesis can also increase in response to inflammation, mechanical irritation (for example, rubbing), a number of infections, parasitic diseases. That is why one of the complications during cosmetic procedures that can be perceived by skin cells as external aggression (peelings, plastic surgery, application of toxic substances to the skin, etc.) is skin darkening - hyperpigmentation.

The risk of hyperpigmentation is especially high in dark-skinned people, whose pigment cells react very actively to any stressful effects. Pigmentation is affected by female sex hormones - estrogens, so hyperpigmentation sometimes appears during pregnancy, when taking hormonal drugs. A number of internal diseases also lead to increased pigmentation.

The list of hypermelanoses is quite extensive, but in cosmetology practice we most often encounter the following problems.

Chloasma (melasma)

Brown or light-brown spots that appear on the face in most cases during pregnancy ("pregnancy mask"), when taking hormonal contraceptives or due to other reasons. The appearance of melasma is explained by the congenital increased sensitivity of melanocytes to stimulating effects - UV radiation, estrogens, etc. Melasma, of course, is an obvious cosmetic defect, but it does not always require treatment.

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Ethnically dark skin

Ethnically dark skin means skin whose dark pigmentation is constitutional (Negroid and Mongoloid skin). Whether or not to undertake total bleaching of ethnic skin is a special question, and each cosmetologist decides it for themselves in accordance with their views on life.

Those who answer this question positively should be prepared for serious problems. Bleaching dark skin inevitably involves interference with the normal physiological processes occurring in the skin. Since dark skin usually resists bleaching, the most powerful products have to be used to achieve a noticeable effect.

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Freckles

Freckles are light-brown, red, yellow (gold) spots that appear on the skin in the spring and summer. Young girls usually turn to cosmetologists with freckles, not fully realizing that skin health cannot be sacrificed for beauty. Therefore, they are ready to apply the most draconian measures to quite pretty freckles. However, it is wiser to prioritize skin health by choosing the most gentle method, even if the effect does not appear too quickly.

Lentigo

These are brown or light brown spots that are slightly raised above the skin surface. In the lentigo area, a combination of hyperpigmentation and keratosis (thickening of the stratum corneum) is observed. A distinction is made between solar lentigo, which is one of the signs of skin damage by UV radiation, and senile lentigo, which usually appears in old age.

Pigmentation after skin injury

Residual hyperpigmentation at the site of the inflammatory process is a common consequence of acne, as well as one of the possible complications after cosmetic procedures associated with skin damage (laser skin resurfacing, dermabrasion, peeling, hair removal, etc.).

The appearance of hyperpigmentation after cosmetic procedures is explained by the fact that melanocytes (cells that produce black and brown pigment) are activated not only in response to UV radiation, but also when the skin is damaged, inflammatory, and other processes accompanied by the appearance of free radicals. Melanocytes are especially easily activated in the so-called ethnic skin - Mongoloid, Negroid, so people with dark skin should be especially careful. Hyperpigmentation can be caused by:

• Any procedures that cause thinning of the stratum corneum - all types of chemical peeling, laser resurfacing, dermabrasion.
• All procedures that involve trauma to the skin - subcutaneous injections, introduction of any implantable materials, facial cleansing for acne, plastic surgery, and also see point 1.
• Anything that causes skin irritation - all types of hair removal, cosmetics that cause an allergic reaction or have a toxic effect on cells, and also see point 1.

Additionally, the skin's tendency to hyperpigmentation is increased by certain substances that increase the skin's sensitivity to UV radiation (photosensitizers). To reduce the risk of developing hyperpigmentation after cosmetic procedures, the following rules must be followed:

• Do not neglect the recommended skin preparation for the procedure. It usually includes the use of antioxidants, UV filters and agents that suppress melanin synthesis.
• After the procedure, do not stop using UV filters before the recommended time. You should know that hyperpigmentation can occur even when the skin is irradiated through glass. And even more so, you cannot sunbathe, even with sunscreen.
• Choose the least traumatic of the proposed cosmetic procedures.
• If you are taking medications, consult a doctor to see if they increase your skin's sensitivity to the sun. Do not take St. John's wort extract (it is a photosensitizer) and do not get carried away with herbs containing a significant amount of psoralens (celery, dill, etc.), do not use photosensitizing essential oils (bergamot oil, all citrus oils) before going outside.
• After procedures that lead to a decrease in the thickness of the epidermis, it is necessary to use preparations that protect the skin from damaging factors and accelerate its recovery.

Pigmentation at the site of the inflammatory process may pass spontaneously, but more often additional intervention is required. Since the appearance of pigmentation at the site of inflammation indicates increased sensitivity of melanocytes to stress factors, bleaching should not create additional stress.

At present, the best strategy for bleaching hyperpigmentation in people with Caucasian skin is developed. The skin of Negroid and Mongoloid people requires a special approach, and its bleaching should be done only by professionals.

Whitening ingredients and their mechanism of action

There are currently a great many ingredients in cosmetology that have a whitening effect to varying degrees. However, the most proven and effective are several ingredients:

Hydroquinone

Hydroquinone, or 1,4-benzenediol, inhibits melanin synthesis by blocking the oxidation of tyrosine to 3,4-dihydroxyphenylamine (DOPA). Since 1961, hydroquinone has been the most commonly used bleaching agent in the United States (it is the only bleaching agent approved by the FDA). Hydroquinone has a strong bleaching effect (whitening occurs in 4-6 weeks), but at the same time, this substance is toxic. In cosmetology, a concentration of 2% hydroquinone is usually used (in the United States, products containing 2% hydroquinone are considered over-the-counter drugs, while products with a concentration of 4% are sold only by prescription).

At a concentration of 5%, hydroquinone begins to damage melanocytes, which are particularly sensitive to it. Higher concentrations can already have a toxic effect on all skin cells. Long-term use of hydroquinone can cause ochronosis - a skin disease accompanied by darkening of the skin and progressive destruction of collagen and elastin fibers. In Europe and the United States, this condition is rare, but in African countries, where hydroquinone is used extremely actively, ochronosis has become a serious problem. Other problems with the use of hydroquinone are skin irritation, hyperpigmentation, and discoloration of the nails.

Hydrogen peroxide

Whitens skin by oxidizing melanin. Hydrogen peroxide is very effective, but can damage skin because it produces free oxygen radicals.

Kojic acid

5-hydroxy-4-pyran-4-one-2-methyl (kojic acid) is a metabolic product of fungi of the species Aspergillus (used in sake production), Aerobacter, and Penicillum. Kojic acid inhibits tyrosinase. Kojic acid is an effective skin whitener, but it can irritate the skin and cause allergic reactions. In addition, it is an unstable substance; it is destroyed by light (it is used only at night) and during long-term storage. More stable is kojic acid dipalmitate. Kojic acid is introduced into cosmetics in a concentration of 1–4%.

Ascorbic acid and its derivatives

Ascorbic acid oxidizes melanin and inhibits its synthesis. Since ascorbic acid is unstable in aqueous solutions, its stable derivatives are more often used in cosmetology - ascorbyl palmitate and magnesium ascorbyl phosphate, which are converted into ascorbic acid in the skin under the action of enzymes.

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Arbutin and deoxyarbutin

Hydroquinone-Beta-D-glucopyranoside (arbutin) is found in a number of plants, but its usual source in cosmetology is bearberry. Unlike hydroquinone, arbutin is non-toxic and suppresses melanin synthesis by reducing the activity of the enzyme tyrosinase. The whitening effect of arbutin is weaker than that of hydroquinone, and it does not affect already formed melanin. Recently, deoxyarbutin has appeared on the cosmetic market, which, according to the manufacturer, whitens the skin more effectively than arbutin.

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Among the whitening ingredients, it is also worth mentioning

Paper mulberry extract - effective in concentrations starting from 0.4%, does not irritate the skin.

Licorice extract - contains glabridin, which inhibits tyrosinase. Glabridin also reduces skin inflammation and prevents UVB-induced pigmentation.

Aloein is a substance found in aloe that inhibits tyrosinase. Because it penetrates the skin slowly, it is often used in liposomal preparations or in combination with substances that increase skin permeability.

The following plant extracts are used as auxiliary ingredients: birch, chamomile, coffee, rue, cucumber, grapefruit, ivy, lemon, papaya, pineapple, rice germ, sea buckthorn, green tea, grapes.

Whitening result

The result that can be expected from the use of any whitening method depends, first of all, on the patient's ethnicity and the nature of the pigmentation - whether its manifestation is pathological or is it a physiological condition in this particular case. In addition, the possibilities of treating melanogenesis disorders also depend on which stages of this process are affected.

So, in order to choose one or another whitening method, you need to try to get answers to the following questions:

• Are the melanocytes in their normal functional state, characteristic of a given skin type, or is their hyperactivity caused by some factors observed?
• Are the factors that caused hyperpigmentation still active and can they be eliminated?
• Is this pigmentation temporary, caused by pregnancy, taking hormonal contraceptives, certain medications, etc.?
• What area of skin will be treated?
• Is this problem even solved within the framework of cosmetology?

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