Cosmetics-induced skin pigmentation, medically known as pigmented cosmetic dermatitis, is due to certain ingredients in cosmetics to stimulate the skin, resulting in overactive melanocytes, or certain substances such as heavy metals absorbed percutaneously, triggering skin pigmentation.

There are three main specific causes:

First, for sensitive skin, certain ingredients in cosmetics may trigger allergic reactions, such as skin redness and stinging, which in turn lead to skin pigmentation.

Second, certain chemical ingredients in cosmetics, such as dyes, may lead to skin pigmentation, which is more common in color cosmetics products and less common in skin care products. In addition, the excessive heavy metal content of informal and substandard cosmetics, such as lead and mercury, may also cause damage to health, including triggering skin pigmentation.

Thirdly, photosensitizing substances in cosmetics may trigger phototoxic reactions and photomorphic reactions, triggering photosensitive dermatitis, leading to symptoms such as redness, swelling and itching of the skin, which may eventually lead to skin pigmentation.

These photosensitizers are commonly found in preservatives and fragrances in cosmetics, as well as in ultraviolet absorbers and sunscreens in sunscreen products. Photosensitizers are also found in retinoids, fruit acids, and essential oils containing furanocoumarins (such as lemon, orange, grapefruit, bergamot, and bitter orange).

There are several ways to prevent and treat pigmented cosmetic dermatitis:

1. When choosing skin care products, choose products produced by regular manufacturers through regular channels and avoid using skin care products of unknown quality.

2. For light-sensitive people, they should try to avoid using skin care products or cosmetics containing photosensitive substances. If you are not sure of your skin type, you can go to a professional organization to conduct a patch test to clarify your skin type.

3. For people who already have abnormal skin pigmentation, they should pay attention to avoiding sunlight and ultraviolet radiation and actively take physical sun protection measures. If the pigmentation is obvious, you can appropriately use anti-pigmentation preparations, such as hydrogen cream. In serious cases, one should seek medical advice and use antioxidants such as glutathione, tranexamic acid, vitamin C, etc., or undergo laser treatment under the guidance of a doctor.

Special reminder, facial skin pigmentation may not be caused by cosmetics, it may be caused by other pathological reasons, such as facial pigmented skin diseases (e.g. chloasma, pigmented lichen planus, etc.), thyroid disease, hypoadrenocorticism, cirrhosis of the liver, and long-term use of certain drugs.

When unexplained skin color changes on the face and neck occur, a clear diagnosis is needed, and a skin biopsy is performed if necessary. In addition, long-term use of anti-tuberculosis drugs such as pyrazinamide, anti-sore drugs such as hydroxychloroquine, anti-tumor drugs such as cyclophosphamide, and so on, may also be one of the triggering causes.