What causes melasma?

Melasma is a common skin condition characterized by the appearance of brown spots on the face, particularly on sun-exposed areas such as the forehead, cheeks, upper lip and chin.

What is melasma?

Melasma, also known as"pregnancy mask" when it occurs in pregnant women, is a hyperpigmentation of the skin resulting from increased melanin production.

What is melanin?

Melanin is a fundamental biological pigment that plays a crucial role in determining skin, hair and eye color in humans and other animals.

Synthesized by specialized cells called melanocytes, melanin is found mainly in the epidermis, the outer layer of the skin.

There are several types of melanin:

• Eumelanin, which is black or brown in color
• Pheomelanin, which is reddish or yellowish

Melanin production is triggered by exposure to the sun's ultraviolet (UV) rays, a process that serves to protect the skin from damage caused by these rays.

Melanin absorbs UV rays, minimizing their penetration into the deeper layers of the skin and reducing the risk of cell mutations and skin cancer. This protective function explains why darker-skinned people, who naturally produce more melanin, are generally less likely to suffer sunburn and certain types of skin cancer than lighter-skinned people.

In addition to its protective and aesthetic roles, melanin is also involved in various biological processes, such as hearing and the regulation of free radicals. However, excessive or irregular melanin production can lead to pigmentation disorders such as melasma, age spots and post-inflammatory hyperpigmentation, underlining the importance of this pigment in skin health and appearance.

What causes melasma?

1. Sun exposure

Sun exposure is the most common cause of melasma. Ultraviolet (UV) rays stimulate melanocytes to produce more melanin, leading to the appearance of brown spots. Sun protection with regular use of sunscreen is essential to prevent and treat melasma.

2. Hormonal changes

Hormonal fluctuations play a crucial role in the development of melasma. This is why the condition is particularly common in pregnant women and those taking the contraceptive pill. Hormonal treatments can also trigger or aggravate melasma by increasing melanin production.

In fact, hormones such as estrogen and progesterone can significantly stimulate melanin production.

3. Genetic predisposition

Genetic predisposition is another important factor. People with a family history of melasma are more likely to develop the condition. Ethnic background can also influence the prevalence of melasma, with people with darker skin at greater risk.

4. Irritating cosmetics

Certain cosmetics and skin treatments can irritate the skin and trigger excessive melanin production. It is therefore advisable to use suitable, skin-friendly products, especially for those predisposed to melasma.

What are the different types of melasma?

1. Epidermal melasma

Epidermal melasma is characterized by excessive pigmentation in the superficial layers of the skin, mainly the epidermis. This type of melasma is generally easier to treat, as depigmenting agents and topical treatments can better penetrate and target melanocytes in this superficial layer. Characteristics of epidermal melasma include well-defined, dark brown spots that are more visible under ultraviolet light.

2. Dermal melasma

Dermal melasma is characterized by deeper pigmentation in the dermis, the skin's underlying layer. This type is often more difficult to treat, as topical agents cannot easily reach the melanocytes located in the dermis. Dermal melasma spots generally appear as greyish-brown patches and are less defined. Under ultraviolet light, these spots are not as visible as those of epidermal melasma.

3. Mixed melasma

Mixed melasma combines the characteristics of epidermal and dermal melasma. It is characterized by both superficial and deep areas of pigmentation. This type of melasma presents a variety of shades, from dark brown to brown-gray, and is visible under ultraviolet light. Treatment of mixed melasma can be more complex, requiring combined approaches to target both the superficial and deep layers of the skin.

4. Melasma indeterminate

In some cases, the depth of pigmentation cannot be clearly determined with the naked eye, or even with the use of specialized devices such as Wood's lamps. This type of melasma is classified as indeterminate until further evaluation can be performed.

 

How is melasma treated?

Melasma treatment depends on the type of melasma (epidermal, dermal, mixed) and the severity of the pigment spots. Here are the main approaches used to treat melasma:

1. Sun protection

Sun protection is essential to prevent melasma worsening. Daily use of a broad-spectrum sunscreen with a high SPF (SPF 30 or higher) helps reduce exposure to UV rays, which can stimulate melanin production and darken existing spots.

2. Topical treatments

• Hydroquinone: This is the most commonly prescribed depigmenting agent for melasma. It inhibits the enzyme responsible for melanin production. Concentrations vary and may require a medical prescription.

• Azelaic acid: This acid acts by inhibiting tyrosinase, an enzyme involved in melanin production. It is often used as an alternative to hydroquinone, especially for sensitive skin.

• Alpha-hydroxy acids (AHA) and beta-hydroxy acids (BHA) such assalicylic acid: These exfoliating acids can help even out skin tone by removing dead skin cells and stimulating cell renewal.

• Kojic acid: Another depigmenting agent that can be used alone or in combination with other ingredients to reduce pigmentation.

3. Chemical peels

Chemical peels, such as those using glycolic, salicylic or trichloroacetic acid, can be used to exfoliate the upper layers of the skin, reduce pigmentation and even out skin tone. They are particularly effective for epidermal melasma.

4. Laser and Intense Pulsed Light (IPL) treatments

Laser and IPL treatments selectively target areas of excessive pigmentation. They can be effective in treating dermal or mixed melasma, fragmenting pigments and stimulating cell regeneration. These treatments must be carried out by qualified professionals to avoid undesirable side effects.

5. Combination treatments

In many cases, a combined approach is the most effective. For example, the use of hydroquinone or azelaic acid in the morning, followed by a chemical peel or laser treatment at appropriate intervals, can provide optimal results while minimizing risks to the skin.

6. Avoid triggers

Avoiding factors that can trigger or aggravate melasma is also important. This includes not only excessive sun exposure, but also the use of skin-irritating products and managing stress, which can influence hormones and aggravate melasma.