Where do brown spots on the hands come from, and how can they be removed?

The brown spots that appear on the hands are not solely the consequence of the passage of time.

They result primarily from the interaction between intrinsic skin ageing and repeated exposure to sunlight. The hands are among the areas most exposed to the sun on a daily basis, often without adequate protection, which promotes the gradual development of irregular pigmentation.

For a long time, it was mainly thought that these marks were due to a local overproduction of melanin. In reality, their formation appears to be more complex. Of course, melanocytes, the cells that produce melanin during melanogenesis, are involved in the process, but recent data show that the problem is not only due to excessive activation of these cells. In solar lentigines, melanin also accumulates because its elimination becomes less efficient. In other words, the skin no longer manages the distribution and clearance of the pigment towards the surface as effectively, which promotes its retention in certain areas.

This pigmentation anomaly is largely explained by gradual transformations of the epidermis. Under the effect of photoageing, the keratinocytes that make up most of this superficial layer no longer renew themselves in such a well‑coordinated way. Several studies have shown that basal keratinocytes proliferate more, while the cells above them desquamate more slowly. This imbalance alters the architecture of the epidermis and promotes the formation of elongated epidermal ridges. These microscopic deformations disrupt the normal upward transport of melanin towards the skin surface, which contributes to its local accumulation and to the darker appearance of the lesion.

The dermis is also involved in this process. With age and chronic sun exposure, fibroblasts, which are responsible for the production of collagen and elastin, become less functional and may enter a state of senescence. They then secrete more inflammatory mediators, metalloproteinases and signalling factors capable of influencing pigmentary activity. At the same time, UV radiation, by inducing significant oxidative stress, activates various inflammatory signalling pathways and disrupts the normal communication between keratinocytes, melanocytes, fibroblasts and even endothelial cells.

Brown spots on the hands result from a collective dysfunction of skin cells, rather than from a simple excess of melanin.

Of course, genetics plays a major role in these processes. Variants of the MC1R gene, well known for their role in the response to sunlight, modulate the activation of melanogenesis via the α-MSH/cAMP pathway, while genes such as MITF or TYR directly regulate the synthesis of melanin within melanocytes. Other genes involved in the management of oxidative stress, such as those regulated by the NRF2 pathway, determine the capacity of skin cells to neutralise free radicals. Thus, for an equivalent level of sun exposure, not all individuals necessarily develop brown spots on their hands.

Among the first visible signs of skin ageing or chronic sun exposure, brown spots on the hands can be a source of cosmetic discomfort. Before considering more invasive medical procedures, certain cosmetic active ingredients can visibly reduce their appearance. By targeting the excessive production of melanin or promoting the exfoliation of pigmented cells, these ingredients offer a gradual yet effective approach to evening out the appearance of the hands and preventing the formation of new spots.

• The vitamin C.

  Vitamin C, or ascorbic acid, is one of the most extensively studied active ingredients for its brightening effect on pigment spots. It acts by inhibiting tyrosinase activity, the enzyme that catalyses the conversion of tyrosine into melanin in the skin. Furthermore, its antioxidant properties enable it to neutralise free radicals generated by UV radiation or pollution, which also stimulate melanogenesis. When used regularly on the backs of the hands in the form of a serum or cream, vitamin C can help to reduce pigment spots.

  A recent study evaluated the effectiveness of a serum containing 15% pure vitamin C, 1% vitamin E and 0.5% ferulic acid on pigment spots on the backs of the hands in 60 volunteers aged 40 to 80 years. Applied twice daily for six months, this treatment proved effective in improving the uniformity of hand colour. Vitamin C, in combination with other antioxidants such as ferulic acid and vitamin E, therefore appears to be of interest for reducing hyperpigmentation.

• The azelaic acid and the glycolic acid.

  Azelaic acid is a naturally derived active ingredient with depigmenting properties of interest for reducing dark spots on the hands. It also acts by inhibiting the activity of the enzyme tyrosinase and has anti-inflammatory and antioxidant activity, enabling it to target different types of hyperpigmentation, including post-inflammatory marks. Glycolic acid, for its part, is an AHA known for its exfoliating effects, allowing it to remove melanin-loaded cells at the surface of the skin. It also accelerates cell renewal within the basal layer of the skin, the deepest layer of the epidermis, where the melanocytes that produce melanin are located.

  A 24-week study was conducted in 60 patients with melasma. Although the condition did not affect the hands, the underlying pigmentary mechanisms are comparable. Participants were divided into two groups. The first group received a 30% glycolic acid peel every three weeks, in addition to twice-daily application of a cream containing 20% azelaic acid. The second group used the cream alone. Assessment was based on the MASI (Melasma Area and Severity Index) score. While improvement was observed in both groups, the reduction in MASI score was markedly greater in patients treated with the combination of glycolic acid and azelaic acid.

• The arbutin acid (or alpha-arbutin).

  Often described as a natural hydroquinone, the remarkable effectiveness of arbutin acid against dark spots is due to its affinity for the active site of tyrosinase. Arbutin acid therefore acts through competitive inhibition : by binding to the active site of the enzyme, it blocks its activity and, consequently, melanin synthesis. A study conducted in India on 36 women with dark spots highlighted the depigmenting properties of arbutin acid.

  For 56 days, the participants applied, twice daily, a cream containing 10% 3,4,5‑trihydroxybenzoic acid glucoside (THBG) and 2% α‑arbutin, in addition to a sunscreen with SPF 50+ used once a day. The effectiveness of the protocol was assessed using a mexameter to measure melanin content, and the MASI score. The results showed a significant reduction in skin pigmentation and in the MASI score, with no adverse effects observed.

• The liquorice extract.

  Under its INCI name Glycyrrhiza Glabra Root Extract, liquorice extract contains 95% glabridin, a compound involved at several levels in regulating the phenomenon of hyperpigmentation. It significantly reduces the amount of endothelin-1, a mediator involved in melanogenesis and released by keratinocytes after UV exposure. Furthermore, liquorice extract inhibits the activity of phospholipase A2 (PLA2), an enzyme released by epidermal keratinocytes after UV exposure or during inflammation, which stimulates tyrosinase activity and thus melanin production. However, to date, the depigmenting effects of liquorice extract have only been demonstrated in vitro.

• The tranexamic acid.

  Tranexamic acid is a synthetic derivative of lysine, an amino acid found in the skin. This active ingredient acts on hyperpigmentation by blocking the interaction between keratinocytes and melanocytes and by competitively inhibiting the active site of tyrosinase, which suppresses its activity and, consequently, the synthesis of melanin.

  Several studies have demonstrated the value of tranexamic acid in the management of dark spots. A recent study assessed the effectiveness of a serum and a cream formulated with 3% tranexamic acid in reducing hyperpigmentation in 22 individuals aged 45 to 67 years. After eight weeks of daily application, a significant reduction of 13% in the colorimetric intensity of the spots and of 6% in their size was observed. Furthermore, 77% of participants reported a visible reduction in their dark spots.

Although certain cosmetic active ingredients can help reduce dark spots, their effects remain gradual and limited; in cases of pronounced hyperpigmentation, only aesthetic medicine can provide rapid and visible results.

As a first-line approach, laser treatment is one of the most effective solutions for brown spots on the hands. Among the most commonly used techniques are the Q-switched laser, IPL (intense pulsed light), and non-ablative fractional lasers. These devices specifically target the melanin contained in the spots : the light energy emitted by the laser is absorbed by clusters of pigment, causing them to fragment into smaller particles that are then gradually eliminated by the body. One to three sessions, spaced several weeks apart, are generally sufficient to achieve a marked improvement. The procedure is rapid and minimally invasive, but may cause some temporary side effects, such as redness or the formation of scabs.

The results obtained with a laser are often highly satisfactory, but they require a thorough prior dermatological assessment in order to rule out any suspicious lesions and to adapt the protocol to the skin phototype.

A recent study assessed the effectiveness of intense pulsed light on brown spots on the backs of the hands in 15 participants aged 40 to 73 years, who underwent three monthly treatment sessions. Follow-up was carried out one and three months after the final session, with image analyses via the VISIA system, a digital imaging system used in dermatology and aesthetic medicine. The results, presented in the table below, show a significant reduction in the number of brown spots, as well as in their intensity and contrast.

Another aesthetic medicine option is professional chemical peels. These are based on the same principle as cosmetic exfoliating treatments but use higher concentrations. Among the most commonly used active agents are glycolic acid, trichloroacetic acid (TCA) and lactic acid, either alone or in combination. The aim is to induce desquamation of the superficial layers of the epidermis containing the melanin clusters, while stimulating the production of more uniform cells. Depending on the depth of the peel, several days of social downtime may be necessary. Multiple sessions are often required and, again, a prior assessment by a healthcare professional is necessary to confirm the protocol and ensure that it is appropriate for the individual situation.

Prevention is better than cure: to avoid brown spots on the hands, it is advisable to protect them daily with a sunscreen.

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