Pico vs Q-switched laser how they differ, and which suits your pigment

The difference

Pulse length is the real difference

A Q-switched laser fires pulses lasting a few billionths of a second (nanoseconds). A picosecond laser fires pulses lasting hundreds of trillionths of a second. In practice the picosecond pulse is roughly ten to a hundred times shorter, and that changes how pigment breaks.

With a Q-switched pulse, the pigment particle heats up and fractures. With a picosecond pulse, the energy arrives so fast that the particle is cracked mainly by a pressure wave, a photoacoustic effect, into smaller fragments. Smaller fragments are easier for the skin's clean-up cells to carry away, and less heat spreads into the surrounding skin.

Wavelength matters as much as pulse length. 1064 nm passes deeper and is absorbed less by the skin surface, which suits darker skin and deeper pigment; 532 nm suits superficial brown spots and red ink; 755 nm and 785 nm target melanin and blue or green ink. Many modern platforms offer more than one wavelength and both pulse types.

Side by side

Pico vs Q-switched laser at a glance

Melasma

Melasma: low-fluence toning, pico, and their limits

Laser toning means using a Q-switched 1064 nm Nd:YAG laser at low energy with a wide beam, passed several times over the face across a course. A systematic review of 42 studies found it generally effective and safe for melasma, especially in Asia, but warned of mottled pale patches with high cumulative energy and of darkening when it is used too aggressively in darker skin. Recurrence after stopping was common.

Picosecond lasers have also been studied for melasma. A meta-analysis of six randomised trials found 1064 nm picosecond laser reduced melasma severity without significant side effects, while 755 nm picosecond laser was no better than lightening creams and caused PIH in some people.

Neither laser cures melasma. It is driven by sun, visible light, heat and hormones, so a doctor usually combines laser with daily broad-spectrum sunscreen, prescription creams and sometimes oral treatment. If someone promises to clear melasma permanently, treat that as a warning sign.

Tattoos

Tattoo removal: where picosecond pulls ahead

Picosecond lasers were first developed for tattoos, because tattoo ink particles are tiny and break more completely with a shorter pulse. A systematic review in the Journal of the American Academy of Dermatology found Q-switched Nd:YAG lasers safe and effective, with picosecond lasers performing better on blue, green and yellow inks; both worked for black ink.

Whichever laser is used, tattoo removal takes many sessions spaced weeks apart, because the body clears ink gradually between visits. Light or dark patches can appear afterwards and usually fade over months. Some colours, especially white and some skin-tone inks used in cosmetic tattoos, can darken when lasered, so a test area is usually done first.

Hori's naevus

Hori's naevus and deeper pigment

Hori's naevus, also called acquired bilateral naevus of Ota-like macules (ABNOM), is a deeper, bluish-grey or brown speckled pigment, usually on both cheeks, and is common in East Asian women. Because the pigment sits in the dermis, creams and peels do little, and it is often mistaken for melasma or freckles. A doctor should confirm which it is before any laser.

Both Q-switched and picosecond lasers are used. A 2026 meta-analysis of 40 mostly small studies found no clear difference in clearance between the two types, and found that more sessions were linked with better clearance; the authors rated the evidence as very low certainty. In one randomised split-face trial of 30 patients, the 755 nm picosecond side cleared better and had less PIH (about 28% compared with 54%) than the 755 nm nanosecond side.

Treatment is usually a short series spaced months apart, and temporary darkening for a few weeks after each session is common. Patience and strict sun protection matter as much as the laser.

Sessions and downtime

Sessions, spacing and downtime by concern

These are general patterns, not a plan. The number of sessions depends on the type of pigment, how deep it sits, your skin type and how well you avoid sun and friction. Results vary, and a doctor sets the course after examining the skin.

Asian skin

Keeping PIH risk down in Asian skin

• Get the pigment diagnosed first: melasma, Hori's naevus, sun spots and PIH need different settings.
• Do not have pigment laser while tanned; treatment is usually deferred.
• Expect conservative settings at the first session, and sometimes a test area.
• Use broad-spectrum sunscreen every day and seek shade; Singapore's UV is high all year.
• For melasma, a doctor may start lightening creams before laser.
• More sessions or more energy is not automatically better; over-frequent toning can cause pale, mottled patches.
• Report any new darkening or lightening between sessions so the plan can be adjusted.

Evidence

What the research says, honestly

A 2021 systematic review of 77 studies on picosecond lasers graded the evidence as level I for tattoo removal, level II for melasma and skin rejuvenation, and level I to IV for benign pigmented lesions, and concluded that picosecond lasers are safe and effective for a growing range of uses.

That does not make picosecond better for everything. For melasma, wavelength and settings seem to matter more than the pulse type, and for Hori's naevus the comparison is still uncertain. Q-switched lasers remain an effective, well-studied tool, particularly for low-fluence toning. Individual results vary.

Where to go

Pico and Q-switched laser in our network

Both lasers are medical treatments. At IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, beside Orchard MRT, Dr Sin Yong performs Pico Laser using the T2 Frax Radiance protocol, on a platform with a 785 nm picosecond output and 532 nm and 1064 nm nanosecond (Q-switched) outputs, and Laser Toning with a 1064 nm Q-switched Nd:YAG. He decides which suits you after examining the pigment. Both are priced at consultation by the clinic; WhatsApp +65 8815 3008.

SkinRev Lab, at CityLink Mall #B1-28 by City Hall MRT, is a non-invasive centre and does not perform lasers. The Needleless SkinBooster (S$288 per region before GST, first region from S$98) can support hydration and overall tone between laser courses, but it does not break up pigment or tattoo ink. See a doctor first about any spot that is new, changing, bleeding or irregular.

Sources

References & sources

1. Wu DC, Goldman MP, Wat H, Chan HHL. A systematic review of picosecond laser in dermatology: evidence and recommendations. Lasers Surg Med. 2021;53(1):9-49.
2. Gurnani P, Williams N, Al-Hetheli G, et al. Comparing the efficacy and safety of laser treatments in tattoo removal: a systematic review. J Am Acad Dermatol. 2022;87(1):103-109.
3. Feng J, Shen S, Song X, Xiang W. Efficacy and safety of picosecond laser for the treatment of melasma: a systematic review and meta-analysis. Lasers Med Sci. 2023;38(1):84.
4. Lee YS, Lee YJ, Lee JM, et al. The low-fluence Q-switched Nd:YAG laser treatment for melasma: a systematic review. Medicina (Kaunas). 2022;58(7):936.
5. Li F, Wang Y, Shen Z. Efficacy of Q-switched and picosecond lasers for acquired bilateral nevus of Ota-like macules: a systematic review and exploratory dose-response meta-analysis. Lasers Med Sci. 2026;41(1):180.
6. Yu W, Zhu J, Yu W, et al. A split-face, single-blinded, randomized controlled comparison of alexandrite 755-nm picosecond laser versus alexandrite 755-nm nanosecond laser in the treatment of acquired bilateral nevus of Ota-like macules. J Am Acad Dermatol. 2018;79(3):479-486.

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