When is Q switch laser the best treatment for acne scars, and can it be combined with other treatments?

Doctor's Answers 5

Hi Janice Lim,

Q switch laser is mainly good for acne marks/post inflammatory hyperpigmentation (PIH). Q switch is primarily used for lightening brown marks/pigmentations. It does not really work for depressed scars. Having said that, PIH on the face often disappears over time unless the trauma is repeated.

Scars that have depression is best treated with fractional CO2 lasers. This is generally the gold standard considering the downtime, benefits and pain issue. Other treatments like subcision and TCA cross are less popular because of risk/downtime vs. benefit ratio.

Subcision is a technique where you use a needle and undermine the underlining fibrotic scars. It should be reserved for stubborn scars not helped as much from fractional CO2 lasers. This tends to be the rolling scars type and maybe the pitting scars. because of the long downtime of 2-4 weeks of bruising if done properly, it is reserved as the next alternative after fractional CO2 lasers. Occasionally, you may also get bumps from over healing althought this is quite uncommon.

I have done thousnds of fractional CO2 lasers and hundreds of subcision and I can tell you that if you just do subcision alone, results may often not be very good because other than softening the fibrosis under the scar, it does very little collagen remodelling.

I have patients who did a series of fractional CO2 laser and then subcision, and find subcision so great, while others who did subcision first and then fractional CO2 laser and finds fractional CO2 laser great.

The point is for some scars both may help bring it up further and people see the latter as the one that brings the effect. In practical sense, it makes more sense doing fractional CO2 laser from experience because for a downtime of a month with subcision and maybe no results, it is disheartening whearas fractional CO2 laser may help the lighter scars improve first and with a relatively shorter downtime, you may be more encouraged to continue.

TCA cross should be left to the last resort. It is reserved for bad ice pick scars which often dont respond to other treatments. It should be used discerningly unlike what many doctors who like to push and advertise or talk about because although it may give good results for those scars, it may also make your scar worse.

This depends ON YOUR OWN HEALING ability and you need to be prepared for such scenarios. Sometimes, before believing what we say, google about the side effects of that treatment and read about the bad things first. Advertisement and pushing of treatments online is common but the practical part of things doesnt always work out like what people say.

Hope that helps you do better research.

Compared to other lasers, most Q-switched lasers have limited effectiveness for treatment of acne scars.

Better treatment options include ablative and non-ablative skin resurfacing lasers. These lasers improve the appearance of acne scars by replacing scarred skin tissue with new skin over a series of laser treatments. They also induce collagen to contract acne scars to make it look smaller.

Ablative lasers include Fractional CO2 and Fractional Erbium lasers. These lasers are effective but have slightly longer downtime of about five days, as compared to non-ablative lasers.

Non-ablative lasers like Fraxel Dual and Fraxel Restore have the benefit of reduced downtime but may take slightly longer to see good results. There are pros and cons to whichever laser you choose.

Recently, PicoSure, a picosecond Laser was approved by the US FDA for treatment of acne scarring and tightening skin. It works by delivering an ultra-short pulse of energy to the skin in picoseconds (trillionth of a second) to create LIOB or laser-induced optical breakdown though photomechanical disruption. There are benefits in using this laser for darker skin types or for people who want minimal downtime.

Laser treatments can be combined with other treatments like subcision, Rejuran® healer, and Skinbooster injections. As acne scars vary from person to person, it would be best to see your doctor for a consultation to determine the best treatment or combination of treatments for you. Hope the above helps!


Dr. Terence Tan

I’m glad to hear that your acne has responded well to doxycycline. It is unfortunate that your battle with acne has caused persistent marks and scars. It must be difficult for you to deal with it. I hope my answer will be able to help you understand Q-switched Laser treatment of acne scars better.

When is Q-Switched Laser the best treatment for acne scars, and can it be combined with other treatments?

Q-switched Laser is the best treatment for acne scars when we want to treat:

1. Flat brown marks known as Post Inflammatory Hyperpigmentation (PIH)

2. Rolling scars when minimal downtime is desired, particularly in darker skin types, using a Fractional Picosecond Laser (such as Discovery Pico, Picosure, etc)

Post Inflammatory Hyperpigmentation

Post Inflammatory Hyperpigmentation (source)

Q-switching and PIH

Q-switching (quality switching) is a technique used to produce short laser pulses with high power. It is widely used in medical lasers. Such lasers may be of various wavelengths (such as 532/1064nm Nd:YAG, 694nm Ruby, 755nm Alexandrite) and pulse durations (nanosecond or the shorter picosecond).

The short Q-switched laser pulses confine the laser energy to small structures such as melanin-containing cells (melanosomes) and produce mostly photomechanical effects. This makes it ideal for treating PIH as most of the laser energy goes to breaking up the excess melanin without too much collateral damage.

I find that for my patients, lasers with higher absorption in melanin (such as Ruby Laser) or newer Picosecond Q-Switched lasers with shorter, more intense picosecond pulses produce better melanin disruption and thus give much faster results. I also prescribe topical medications that inhibit melanin formation to speed up the resolution of PIH. Sunblock with SPF at least 30-50 is essential.

Q-switching and Scarring

Q-switched Lasers in the form of Fractional Picosecond Lasers are great at treating shallow rolling scars

  • ideal for busy patients as they generally do not require much downtime beyond mild temporary redness for about 1 day
  • ideal for darker skinned patients that have higher risks of complications (such as PIH) with other scarring treatments such as Fractional Lasers

In Fractional Picosecond Laser treatments, high powered Q-switched laser pulses are delivered in a picosecond (trillionth of a second) via a special fractional hand-piece that further concentrates the laser energy into many small pin-point treatment zones.

Added together, these treatment zones constitute a fraction of the treated skin surface, hence the appellation ‘fractional’. This concentrated laser power is absorbed by structures in the skin, triggering Laser Induced Optical Breakdown (LIOB) and associated shockwaves.

The intense photomechanical stimulus triggers scar remodeling and collagen production. As melanin absorbs the laser energy and forms a focus for the subsequent plasma formation and cavitation, LIOBs are actually produced more efficiently in darker skin patients.

Fractional Microneedling Radiofrequency or Fractional Laser may produce more obvious results, but each treatment has its own strength and weaknesses. It’s imperative to evaluate the type and configuration of scarring, skin type and colour, as well as patient lifestyle and budget.

Lasers and other energy-based scar treatments can be combined with scarring treatments such as Subcision, Filler, TCA Cross, Rejuran, Skinboosters for better results. In fact, combination treatment usually yields better results as most patients have a combination of scar types.

Acne treatments such as hydradermabrasion, chemical peels, oral and topical medication can also be done concurrently. The type and sequence of combination treatment has to be individualized to each patient. I personally prefer to start with the more obvious scars first.

Do consult a doctor who can assess your scars in person, explain the pros and cons of each treatment and advise on the most suitable approach for your skin, scar type, and lifestyle, as even the best treatment available may not be the best treatment for YOU.

Hope this explanation makes things clearer for you!

Warmest regards,

Dr. Wan Chee Kwang


1. Cho SB et al. Treatment of post-inflammatory hyperpigmentation using 1064-nm Q-switched Nd:YAG laser with low fluence: report of three cases. J Eur Acad Dermatol Venereol. 2009;23:1206–1207.

2. Bernstein EF et al. Treatment of acne scarring with a novel fractionated, dual-wavelength, picosecond-domain laser incorporating a novel holographic beam-splitter. Lasers Surg Med. 2017 Nov;49(9):796-802.

3. Bhargava S et al.Acne Scarring Management: Systematic Review and Evaluation of the Evidence. Am J Clin Dermatol. 2018 Aug;19(4):459-477.

Q-switched Laser is the best treatment for acne scars that are Brown Spots called Post-Inflammatory Hyperpigmentation.

Other types of Acne scars such as depressed scars (rolling scars is a type of depressed scar) and hypertrophic scars are better treated with subcision, fractional ablative/non-ablative lasers, fractional RF.

Yes, Q-switched Laser can be combined with other treatments if you have multiple types of acne scars. In fact, Acne scar treatments should be specific and customised for each type of acne scar.

In general, a single session of acne scar treatment can range from $300 to $800.

For specific details, check out this Guide on Acne Scar Treatment Costs in Singapore.

I suggest that you consult a doctor who offers a comprehensive range of acne scar treatments.

Hope that this helps!

Warmest regards,

Dr Justin Boey

I am happy to hear that your acne has come under control with doxycycline. Pertaining to your hyperpigmentation, you can utilise either Q switch laser/Picolaser or for some lesions, consider IPL/yellow laser to reduce the severity of the condition.

Q switch does nothing really for scars. It helps the hyper pigmentation primarily.

I like subcision with the use of Radiesse and have performed many of the procedures and patients (if well selected) like the results. Fractional Laser would be the next step once the deep scars are dealt with, and the downtime is about 4-5 days (reasonable).

TCA cross is best for icepick scars and the downtime is like 7-14 days (social downtime) as you may look dotty for the period. Discuss with your doctor clearly on your scars and treat accordingly


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