Melasma involves the skin barrier, basement membrane, dermis and vessels — not pigment alone. Why session counts alone cannot define a treatment course.
Written and reviewed by Dr. Lee Yumin, MeSOnBom Clinic
Hello. This is Dr. Lee Yumin of MeSOnBom Clinic.
When a cool breeze starts to appear morning and evening, the change of season becomes noticeable in dermatology practice too.
Skin exposed to strong ultraviolet light through the summer tends to show darker melasma and blemishes, and enquiries about pigmentation treatment naturally increase at this time of year.
In melasma consultations I am often asked, "If I have about ten pico toning sessions, will the melasma go?"
But the course of melasma treatment is difficult to define by a number of sessions alone.
Even where melasma looks the same, the treatment method and duration can differ with the depth and distribution of the pigment and the condition of the skin barrier.
Today I want to explain why melasma treatment takes longer than expected, and what matters most to watch during the course of treatment.
Melasma is a chronic pigmentary condition in which changes across several layers of the skin are involved, not only the visible melanin.
Continuing treatment while monitoring the condition of the skin therefore matters more than removing pigment in a short period.
Although it may look like a similar brown pigmentation on the surface, the changes occurring within the skin are not all the same.
Unlike freckles and some blemishes, which sit relatively superficially, research reports that melasma skin shows not only epidermal pigment change but also basement membrane damage, solar elastosis in the dermis, vascular changes, mast cells and senescent fibroblasts. [References ①, ②]
In other words, melasma is not resolved by removing a single visible pigment; it is a condition in which the skin environment that produces and maintains the pigment must also be considered.
Because of this, pigmentation treatment cannot proceed identically for every case of melasma — the direction of treatment needs to be adjusted while checking the present pattern of pigmentation, the skin's condition, and its response to treatment.
The outcome of pico toning is difficult to judge from a fixed number of sessions.
More important than how many sessions have been done is how the pigment is changing during the course, and how the skin is responding to treatment.
A pico laser delivers energy in extremely short pulses measured in picoseconds, and is used when targeting melanin pigment.
Results of melasma treatment with a pico laser can differ according to the wavelength used and the treatment conditions.
A 2023 analysis pooling several studies confirmed lightening of melasma after pico laser treatment, but reported differences in outcome according to the wavelength used and the treatment conditions. [Reference ②]
When planning pigmentation treatment, then, it is more important to observe how the pigment and the skin's condition are changing during the course than to take the number of pico toning sessions as the measure.
Melasma can involve changes in the skin barrier, the basement membrane, the dermis and vascular elements as well as the pigment itself.
There can therefore be limits to treating repeatedly with only the visible pigment as the target.
Recent research analysing the skin microenvironment in melasma likewise reports impaired skin barrier function, basement membrane damage, solar elastosis and vascular change together. [Reference ①]
Where the skin is dry and sensitised, or redness is also present, the direction of treatment needs to be adjusted in light of the skin's present condition rather than repeating pigment treatment alone.
A study of laser-based melasma treatment analysing 52 studies and 1,058 patients also explains that, given the variability of outcomes and the possibility of recurrence, laser treatment needs to be approached in combination with strict sun protection and topical treatment. [Reference ③]
The reason melasma treatment takes time cannot, in the end, be explained simply by the pigment being deep.
It is because the factors currently affecting the melasma in the skin must be identified, and the direction of treatment adjusted to the skin's condition.
Q. How long does melasma treatment usually take?
A. Melasma is a pigmentary condition that can recur chronically, and the duration of treatment differs with the skin's condition and the method used. Rather than fixing a duration at the outset, it is better to treat for a period and then adjust the plan while observing the change in pigment and the skin's response. [References ①, ④]
Q. Will more pico toning sessions improve melasma faster?
A. Not necessarily. Results with a pico laser are reported to differ with wavelength and treatment conditions, so building a pigmentation treatment plan suited to the skin's condition matters more than increasing the number of sessions or the intensity. [Reference ②]
Q. Can melasma darken again after treatment?
A. Yes. Melasma has a tendency to recur, with ultraviolet light, hormones and various changes within the skin all involved. Sun protection and consistent skin care therefore remain important after treatment. [References ①, ④]
In treating melasma, establishing the present state of the pigmentation and the characteristics of the skin matters more than how many pico toning sessions are done.
The intensity and the intervals need to be adjusted while observing the changes that appear during the course.
Even where melasma looks the same, the depth of pigment, the condition of the skin and the response to treatment differ, so adjusting intensity and interval while watching those changes matters more than meeting a set number of sessions.
If you are considering treatment for melasma, please establish the present state of the pigment and your skin fully, and then build a plan suited to you.
① Ali L, Al Niaimi F. Pathogenesis of Melasma Explained. International Journal of Dermatology. 2025;64(7):1201-1212.
② Gu D, et al. What lies behind melasma: a review of the related skin microenvironment. International Journal of Dermatology. 2025;64(2):256-265.
③ Feng J, et al. Efficacy and safety of picosecond laser for the treatment of melasma: a systematic review and meta-analysis. Lasers in Medical Science. 2023;38(1):84.
④ Chua KR, et al. Assessing the Safety and Efficacy of Picosecond Alexandrite Lasers in the Management of Melasma: A Systematic Review and Meta-Analysis of Randomised Control Trials. Australasian Journal of Dermatology. 2026;67(3):140-150.
⑤ Aljoaib NN, et al. Efficacy and Safety of Laser-Based Therapies for Melasma: A Systematic Review and Meta-Analysis. Cureus. 2026.
Written by Dr. Lee Yumin — MeSOnBom Clinic
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