In short. A picosecond laser delivers pulses about a thousand times shorter than an older nanosecond pigment laser. The pulse ends before heat can spread, so pigment fractures under a pressure wave rather than being slowly heated. That usually means less injury to surrounding skin and a faster recovery — but it does not make pigment clear in one session, and darker skin still needs cautious settings.
Key points
- Shorter pulses mean less heat to surrounding tissue, not more power.
- Used for sun spots, freckles, PIH, selected melasma, and tattoo removal.
- It does not resurface texture, tighten skin, or replace fractional lasers.
- Melasma is treated with extreme caution and is rarely a laser-first problem.
- Three to six sessions, six to eight weeks apart, is a common plan.
What is different about a picosecond pulse?
A nanosecond pulse heats pigment long enough for neighbouring tissue to warm with it. A picosecond pulse ends before that heat spreads, so the pigment particle fractures under a sudden pressure wave. The fragments are smaller and are cleared by the lymphatic system more efficiently. This matters most for stubborn pigment, tattoo inks that resist older lasers, and darker skin tones where thermal injury is the main concern.
| Picosecond | Nanosecond (Q-switched) | |
|---|---|---|
| Pulse length | Trillionths of a second | Billionths of a second |
| Main effect | Photoacoustic fragmentation | Photothermal heating |
| Heat to surrounding tissue | Lower | Higher |
| Typical use | Pigment, tattoos, selected melasma | Pigment, tattoos |
| Recovery | Usually faster | Variable |
What does it treat, and what does it not?
It is used for sun spots, freckles, post-inflammatory hyperpigmentation, melasma with extreme caution, and tattoo removal across a range of colours. It does not resurface texture, lift tissue, or replace skin-tightening devices. For acne scars, deep wrinkles, or laxity, fractional lasers or energy-based devices are the appropriate tool.
What happens in a session?
After skin-type review and a test spot, the clinician treats the area with a focused handpiece. The sensation is brief and sharp; topical numbing is routine. Brown marks look like fine dust for about a week before clearing. Redness settles within hours to a couple of days. Most plans involve three to six sessions, spaced six to eight weeks apart.
Is it safe in Asian skin?
Picosecond pulses reduce, but do not eliminate, the risk of post-inflammatory hyperpigmentation in melanin-rich skin. Treatment is staged conservatively: lower fluence, longer intervals, test spots, and strict sun protection between sessions. Pigment rarely clears in one pass, and pushing harder does not make it clearer.
Who should postpone or reconsider?
- Active tan, recent sunburn, or photosensitizing drugs — defer until the skin is calm.
- Active melasma, eczema, or a history of keloid scarring — review risk and benefit with a dermatologist first.
- Persistent pain, blistering, or unusual pigment change after a session — early review can limit long-lasting colour shift.
Sources
- NICE — guidance on laser treatment for pigmented skin lesions
- Cochrane Library — reviews of laser and light treatments for pigmentation
- American Society for Laser Medicine and Surgery — patient safety information
Internal links
Frequently asked questions
How does a picosecond laser differ from an older pigment laser?
The pulse is about a thousand times shorter than a Q-switched nanosecond pulse, so pigment fractures under a photoacoustic pressure wave instead of being slowly heated. Less heat spreads to surrounding tissue, which usually means less collateral injury and a faster recovery.
Does it work for melasma?
Melasma is treated with extreme caution and is rarely a laser-first problem. Picosecond pulses reduce, but do not eliminate, the risk of post-inflammatory hyperpigmentation, so treatment is staged with lower fluence, longer intervals and strict sun protection. Pigment rarely clears in one pass.
Is a single session ever enough for a tattoo?
Tattoo removal often requires many sessions and may leave residual colour or a faint ghost of the original. The number depends on ink colour, depth, age and density. Some colours respond poorly to any laser, so clearance is discussed honestly rather than promised.
Risks & Limitations
- Burns and blistering if settings do not match the skin.
- Post-inflammatory hyperpigmentation, particularly in darker skin types, which may take months to settle.
- Hypopigmentation (lightening) of treated skin, which can be permanent.
- Scarring, including hypertrophic scarring, which is uncommon but real.
- Infection, including reactivation of herpes simplex after resurfacing.
- Acne or milia flare during recovery.
- Results are incremental and most concerns need several sessions. Melasma may rebound or worsen with aggressive treatment.
When to Seek Care
- Blistering, weeping or broken skin beyond the expected reaction.
- Severe pain that is worsening rather than settling.
- Spreading redness, warmth, pus or fever.
- New darkening or firmness that looks like scarring at the treated area.
- Any change in a treated pigmented lesion — it should be reviewed, not retreated.
References & Further Reading
- American Academy of Dermatology (AAD) — laser and energy device information
- American Society for Laser Medicine & Surgery (ASLMS)
- National Medical Products Administration (NMPA, China) — device registration status
- Cochrane Library — systematic reviews in laser dermatology
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.