Why does pigmentation occur after laser treatment?

Asian skin typically has more melanin and a higher reactivity of melanocytes (Fitzpatrick skin types III to IV), which means the risk of PIH is higher than in Caucasians. The risk of pigmentation increases with darker skin types. In particular, with ablative lasers (such as CO₂) that remove the skin surface, the frequency of PIH is reported to be significantly higher in skin type IV and above. In clinical practice, we often see that even with the same laser, pigment reactions vary greatly depending on skin type.

Therefore, for Asian skin, it is important to use equipment that allows energy to be divided over multiple sessions rather than applied strongly at once, and to select wavelengths and modes according to the skin's condition. For example, a triple-wavelength laser (such as Soprano Titanium) used in hair removal and pigment treatments, which allows control of depth and energy delivery, can help reduce the burden on Asian skin.

Ultraviolet (UV) radiation is the most powerful direct stimulator of melanocytes. If you do not protect your skin after a procedure, pigmentation is more likely to occur, and any existing pigmentation may become darker. Immediately after laser treatment, the skin barrier is temporarily weakened and inflammatory signals remain. When UV exposure is added, the stimulation of melanin production overlaps, potentially increasing both the likelihood and duration of pigmentation.

For at least 4 weeks after the procedure, it is recommended to apply a sunscreen with SPF 50+ and PA+++ or higher every day, and reapply every 2 to 3 hours when outdoors. UV (especially UVA) reaches the skin even on cloudy days and through indoor windows, so it is advisable to maintain protection regardless of season or weather. Combining physical barriers such as hats and umbrellas can be even more helpful.

If PIH has already developed, it will usually fade gradually over time, so the priority is not to add further strong irritation in a hurry. Epidermal pigmentation is known to improve over several months (approximately 3 to 9 months), while pigment that has reached the dermis may take longer. Maintaining sun protection during this period is crucial for the speed of recovery.

If you wish to speed up recovery, you may consider stepwise options such as prescription whitening agents (hydroquinone, tranexamic acid, vitamin C, etc.), low-intensity laser toning, or gentle peels at a dermatology clinic. However, applying strong stimulation to the pigmented area again could worsen it, so it is safer to decide which method to use and when based on an evaluation of the pigment depth and skin condition.

The key to prevention lies in three elements: sun protection, restoring the skin barrier through moisturizing, and avoiding physical irritation. During the recovery period after the procedure, using a gentle cleanser and moisturizer to quickly restore the skin barrier is the fastest way to reduce inflammation. If scabs or flakes form, do not pick at them; let them fall off naturally.

Physical irritation such as scrubs, exfoliants, or abrasive cloths, as well as high-temperature environments like saunas and steam rooms, can stimulate inflammation and should be avoided for at least 1 to 2 weeks. Consult your clinic about when to resume using retinoids or high-concentration acid-based skincare products. If redness persists or the area begins to darken, visiting the clinic early to establish a management plan can help reduce pigmentation. We recommend determining the appropriate treatment intensity and care plan for your skin type through a consultation with a dermatologist.