The follow-up question
A patient comes back six months after her first PicoSure session and says, "The spots are coming back. Did it not work?"
It worked. The Pico did what a Pico does. The conversation she and I need to have is about what that is, what it is not, and why the picosecond laser is one of the most useful tools in modern pigment medicine without being a one-shot solution to anything.
What picosecond actually means
A picosecond is one trillionth of a second. To put that in scale: in the time it takes you to blink, a picosecond laser fires roughly four hundred million pulses, each one impossibly brief.
The previous generation of pigment lasers worked in nanoseconds, one billionth of a second. Both are extraordinarily short. The difference between a nanosecond pulse and a picosecond pulse is roughly the difference between a single hand clap and a fingersnap repeated a thousand times in the same instant. The biology that picks up the energy responds to each differently.
Pigment in the skin sits in clumps inside cells called melanocytes. Older lasers heated the pigment, broke it down by thermal energy, and relied on the surrounding tissue to clean up. The longer the pulse, the more heat spilled into nearby skin, and the higher the risk of post-inflammatory pigment as a side effect.
A picosecond pulse is so brief that the energy delivered behaves less like heat and more like a mechanical shock. The pigment clump shatters into smaller fragments without warming the tissue around it the same way. The body's own clearance system carries the fragments away over the following weeks. Less collateral heating. Less risk of paradoxical pigment. Finer fragmentation. More efficient clearance. That is the whole pitch, and most of it is true.
Why this matters more for some pigment types than others
Not all pigment is the same. The Pico advantage is real, and it is not uniform across every pigment problem.
For superficial epidermal pigment, the sunspots and freckles that sit close to the skin surface, picosecond technology works very well. The fragments are small enough that the body clears them efficiently, and the side effect profile is favourable.
For deeper dermal pigment, including some types of melasma and certain post-inflammatory pigmentation, the story is more nuanced. Pico can help, and treatment has to be more careful. Settings appropriate for surface pigment can drive deeper pigment cells into an inflammatory response that worsens the appearance instead of improving it. This is where doctor judgement and patient selection matter more than the device itself.
There is a longstanding caution in dermatology about aggressive laser treatment in melasma, including with picosecond devices. The condition has vascular and hormonal drivers in addition to pigment, so a laser that perfectly targets pigment can still miss the underlying mechanism. A patient with melasma who is told that a single laser will solve her problem has been promised more than the technology can deliver.
For tattoo ink and certain birthmarks, picosecond lasers have shifted what is possible in a way the previous generation rarely managed. Inks once considered untreatable now respond, and the number of sessions required has dropped meaningfully.
What a single session can and cannot do
In real patients, single-session expectations rarely hold up. Most pigment problems benefit from a course of treatments spaced weeks apart, with the body's clearance doing its work between sessions. For surface pigment, three to six sessions for visible improvement is typical. For deeper or more stubborn pigment, longer.
What a single session can do: lift the appearance of recent, well-defined surface lesions. Brighten the overall tone of skin that has accumulated low-grade sun damage. Make the next session more effective by softening the field.
What a single session cannot do: clear pigment laid down over fifteen years of cumulative sun exposure in one go. Stop new pigment from forming. Treat a condition that has hormonal or inflammatory drivers without addressing those drivers.
This last point is where most disappointment lives. The patient sees a clean result two weeks after her session. Two months later the same areas are darkening again. She concludes the laser did not work. The laser worked. The pigment-producing cells were never the target the laser could reach.
The honest limit, and what the consultation looks like
PicoSure is one of the most useful tools the clinic has for pigment, and it earns its place in many treatment plans. It is one element of a longer plan, not the plan itself. The pigment cells that produce the colour you are trying to remove are still there after the session, and so are the conditions that activated them in the first place: sun exposure, hormones, heat, inflammation.
A good consultation about pigment treats the laser as one element among several. We talk about how the pigment got there. We talk about what triggers it. We talk about what daily protection looks like for the life you actually live, the school run at noon, the cooking over a hot wok, the office windows you sit beside without noticing. The session itself is the most visible part of the work and rarely the most important part.
The patient who returns six months later asking whether the Pico worked is in fact asking the right question. The answer is: it worked on the pigment that was there. The question we should both be asking next is what is putting new pigment there, and what the plan is to address it.
That conversation is more boring than a laser session and far more decisive in how her skin will look in three years.
