The short answer
Post-inflammatory hyperpigmentation, or PIH, is the dark mark left after acne, eczema, friction or another injury to the skin. Many of these marks fade by themselves once the cause is under control.
The core of management is cause control, daily broad-spectrum sun protection and time. Prescription creams such as hydroquinone, tretinoin or azelaic acid are a doctor's decision after assessment. Pico laser is considered later, for marks that stay.
How pico laser for dark marks is used
A picosecond laser is used as low-energy toning across the mark, not as a higher-energy spot treatment. Settings favour longer wavelengths, low fluence, a larger spot and long intervals between sessions. For dermal pigment, 1064 nm or 785 nm may be used. The very short pulse works mainly through pressure, with less heat spreading into nearby skin than longer pulses produce.
Reading the depth of a mark
| What it looks like | Likely depth | What to expect |
|---|---|---|
| Brown, with a defined edge | Epidermis | Tends to clear faster |
| Grey or slate-blue, with a softer edge | Dermis | Clears slowly or incompletely |
| Pink or red | Vessels, not pigment | Not a picosecond target |
Who it may suit
Marks that remain after the cause has stopped may be considered.
Fitzpatrick IV to V skin may be considered, after a test area is treated first.
These are considered cautiously, if at all, with expectations set at consultation.
Who should wait, or look elsewhere
Marks from acne, eczema or friction that is still ongoing should wait. Laser over active inflammation is not advised.
These are post-inflammatory erythema. A laser absorbed by blood or the R2 Glow protocol is the relevant category.
Recent tanning, photosensitising medicines or recent isotretinoin mean treatment is deferred.
Melasma is ruled out first, as it is managed differently.
What it cannot do
Pico laser cannot stop marks forming while the cause is still active. It is not used for pink or red marks. Dermal pigment may clear slowly or only partly, and response varies from person to person. Laser also does not replace sun protection. Without it, marks can stay or return.
Risks and side effects
The laser can cause the problem it treats. Energy that is too high, stacked passes, repeat treatment before the skin settles, sun exposure and treating over inflammation are all causes. New darkening can take a long time to fade.
These have been linked to frequent repeated toning of the same area.
Redness and warmth are expected and pass. Blistering or pinpoint bleeding is uncommon, and is seen at higher energies.
Picking, scrubbing or restarting exfoliating acids too soon adds inflammation.
Sessions and fees
No fixed number of sessions or interval is set in advance. Intervals are long, and toning does not run on a standing schedule. A mark that darkens after treatment is reviewed and rested, not treated again. Fees are set in writing after assessment. They depend on the area, the depth and extent of the marks, whether a test area is used and how the plan is staged. Singapore's rules prevent prices from being advertised. Please get in touch to have your marks assessed.