Why repeated toning leaves melasma unchanged

A split-face design within the same patient

To find out whether toning works on melasma you have to compare it against an untreated side under the same conditions. Melasma and daily habits differ so much between people that comparing across patients mixes those differences into the result. The researchers divided each face in two, treating one side with toning and the other with a placebo procedure.

Participants had Fitzpatrick skin types I to IV and a melasma score (mMASI) of 2 or above. The mMASI combines how far the pigment spreads with how dark it is into a single score. Treatment was given three times at monthly intervals.

Both sides received exfoliation, 4% hydroquinone and sunscreen. Toning was not tested on its own. The design asked what toning adds on top of that topical regimen.

The assessors scored the results without knowing which side had been treated. This is called blinding and is used to keep expectation out of the assessment.

Improvement on the treated and the untreated side

Both sides improved to a similar degree. The side that received toning did not improve more than the other.

Both improved because both were on hydroquinone and sunscreen. That is where the lightening came from, and no additional contribution from toning was detected on top of it.

What patients themselves perceived moved differently. Perceived improvement peaked around week 8 and had fallen back by six months. It felt better while treatment was ongoing, and that impression faded with time.

Toning on top of topicals versus toning on its own

What the trial shows is that adding toning for someone already using hydroquinone and sunscreen properly produced no measurable gain.

Reading that as toning being useless goes too far. Toning without topicals was not one of the arms in this trial.

In order of operations: when the patches are not moving, checking how sunscreen and topicals are actually being used comes before adding sessions. That is where the improvement in this trial came from.

What this trial does not answer

Start with skin type. Only Fitzpatrick I to IV were enrolled. The higher the number the darker the skin, and darker skin is more prone to rebound pigmentation after toning. Patients treated for melasma in Korea who fall in that higher range are barely represented here.

• Both sides used hydroquinone and sunscreen. This was not a test of toning on its own
• Only Fitzpatrick I to IV were enrolled, so darker skin is not represented
• The result covers three sessions at monthly intervals. Other intervals and session counts were not examined
• The design was not built to capture late responses such as rebound pigmentation or hypopigmented spots
• In a split-face design the two sides of one face are never perfectly identical

Melasma is driven by ultraviolet light, hormones and heat at once, which makes isolating the contribution of any single device difficult to begin with.

When the patches are not moving

If sessions keep being added and the patches stay the same, there is something to check before looking for a stronger device. What produced the improvement in this trial was the topical treatment and the sunscreen.

Counting how many times a day sunscreen is reapplied, how many months the lightening cream has been in use and how long the gaps in between have been comes first.

Melasma is closer to a condition that is managed than one that is cleared. Perceived improvement peaking at week 8 and dropping by six months fits the same picture.

The practical takeaway

What this trial shows is that more toning may not be the answer. Added on top of topicals and sunscreen, toning produced no measurable extra lightening.

It is equally hard to move from there to toning being useless. Toning without topicals was not compared, and Fitzpatrick V and above were essentially absent.

If the conversation starts with the number of sessions, it is worth raising sun protection and topicals alongside it.

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