Why has Q-switch treatment been ineffective for my acne scars and hyperpigmentation? (photo)

Doctor's Answers 3

Sorry to hear that you have not had good results with your current Q-switched treatment. Q-switched Laser treatment has become relatively widespread in Singapore and patients have been asking me similar questions more often. Thank you for allowing me to clarify.

Why has Q-Switched Laser treatment been ineffective for your Acne scars and hyperpigmentation?

In order to understand this, we need to delve a little into how lasers interact with our skin.

  1. Laser energy has to be absorbed in the correct skin structure while sparing the rest of the skin (selectivity) to produce the desired effect.

    Selectivity is affected by the relative absorption of the laser wavelength in various components of the skin (‘chromophores’ such as melanin, water, and blood)

  2. The laser also needs to penetrate deeply enough with an adequate energy level.

    This is affected by laser parameters such as spot size and energy/fluence.

  3. Once absorbed, the biological effect of the laser would depend on the pulse duration.

    Shorter pulses would produce more of a photomechanical effect (to break apart the target) whereas longer pulses produce more photothermal (heat) or even photochemical (stimulation of chemical reactions) effect.

    In order to confine the laser energy to a particular skin structure, the pulse duration needs to be less than the target’s thermal relaxation time, which is a measure of how fast energy is dispersed.

While it is not clear what sort of Q-switch Laser treatment you have undergone, it is likely to be a nanosecond Q-switch Nd:YAG Laser with wavelengths of 1064nm and 532nm which is available in many aesthetics clinics (it seems to be more common in large chain clinics).

Most of the time, these lasers are used to do Laser Toning or ‘Laser Facials’ using 1064nm wavelength, low energy/fluence, and large spot size.

The 1064nm wavelength is very versatile as it is absorbed by melanin, blood, and water. However, it has relatively lower absorption compared to other laser wavelengths.

The Q-switching (quality switching) mechanism creates short nanosecond laser pulses, confining the laser energy to small structures such as melanin-containing cells (melanosomes) and generating a mostly photomechanical effect.

Nd:YAG laser has a relatively low melanin absorption.

NdYAG laser has a relatively low melanin absorption.

Q-switched Laser and Pigmentation

In my experience, while laser toning can be effective for Hyperpigmentation, including Post Inflammatory Hyperpigmentation (PIH) resulting from Acne, numerous sessions are required as the low energy and the relatively low melanin absorption of the 1064nm wavelength results in gradual pigment clearance.

I find that for my patients, lasers with higher absorption in melanin (such as Ruby Laser) or new 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.

Based on my experience, nanosecond 1064nm Q-switched Nd:YAG laser toning does not help much for Depressed Acne Scars.

Most effective scar treatments rely on creating critical controlled photothermal damage which:

  • Disrupt scar tissue
  • Stimulate skin remodeling
  • Promote new collagen synthesis.

The short nanosecond pulse duration and low energy together with the low water absorption of the 1064nm Q-switched Nd:YAG Laser does not produce enough critical photothermal damage to improve the scarring.

Scarring treatments that worked for my patients include:

  • Fractional Laser (such as CO2, Erbium Glass)
  • Fractional Radiofrequency Microneedling
  • Fractional Picosecond Q-switched Laser.

Fractional Lasers have longer pulse durations and wavelengths that are absorbed mainly by water (which constitutes 80% of skin). They generate critical photothermal effects to stimulate scar remodeling.

The more aggressive parameters penetrate deeper, producing more effect. However as the laser needs to penetrate the skin surface first, more aggressive settings typically result in more discomfort, downtime, and risk of complications such as PIH.

Fractional Radiofrequency Microneedling works similarly except that fractional radiofrequency energy is delivered via microneedles directly to the deep dermis, sparing the skin surface. This allows us to treat the skin more aggressively and deeply for better results while avoiding some of the drawbacks of fractional lasers such as pigmentary changes and downtime.

Having said all that, it is not true that Q-switched Lasers do not have any effect on scarring! Newer Picosecond Q-switched Lasers often have a fractional modality able to generate Laser Induced Optical Breakdown (LIOBs) which have been showed to improve Acne Scarring via an intense photomechanical effect.

From the photos you have provided, it appears that you mainly have Acne Scarring and Post Inflammatory Erythema. I do not see much Post Inflammatory Hyperpigmentation.

Treatments that could work for you would be:

  • Fractional Radiofrequency Microneedling
  • Fractional laser
  • Fractional Picosecond Laser.

These may help with the Post Inflammatory Erythema too, so you may want to try them before dedicated treatments for the Post Inflammatory Erythema, such as long pulsed vascular lasers (e.g. pulsed dye, Nd:YAG, 532nm green laser).

It is also essential to control your acne in order to prevent new scars from forming. It would be pointless to focus on treating the scars while new scars are constantly being generated by poorly controlled Acne. Some research does suggest that Fractional Laser or Fractional Microneedle Radiofrequency treatments do help with Acne control.

In my practice, I start patients on topical and/or oral medications (before or when starting treatment) as well if their acne is not well under control.

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.

Hope this helps!

Warmest regards,

Dr. Wan Chee Kwang


  1. Bogdan Allemann I et al. Laser principles. Curr Probl Dermatol. 2011;42:7-23
  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. Deirdre Connolly et al. Acne Scarring—Pathogenesis, Evaluation, and Treatment Options. J Clin Aesthet Dermatol. 2017 Sep; 10(9): 12–23.
  4. Park KY et al. Comparison of fractional, nonablative, 1550-nm laser and 595-nm pulsed dye laser for the treatment of facial erythema resulting from acne: a split-face, evaluator-blinded, randomized pilot study. J Cosmet Laser Ther. 2014 Jun;16(3):120-3.
  5. Kwon HH et al. Novel device-based acne treatments: comparison of a 1450-nm diode laser and microneedling radiofrequency on mild-to-moderate acne vulgaris and seborrhoea in Korean patients through a 20-week prospective, randomized, split-face study. J Eur Acad Dermatol Venereol. 2018 Apr;32(4):639-644.
  6. Moneib H et al. Randomized split-face controlled study to evaluate 1550-nm fractionated erbium glass laser for treatment of acne vulgaris--an image analysis evaluation. Dermatol Surg. 2014 Nov;40(11):1191-200.

Sorry to hear that your Q-switched treatments have been ineffective for your acne scars and hyper pigmentation.

From your photo, you have Depressed Acne Scars like Ice pick scars. You also have Post-Acne Erythema (Redness).

Q-switched Nd:YAG nanosecond Lasers are good lasers for treating Brown spots/pigmentation due to their wavelengths of 532nm and 1064nm.

However, Q-switched Nd:YAG lasers cannot treat Depressed Acne Scars and Post-Acne Erythema.

For Depressed Acne Scars like Ice Pick Scars: I suggest more effective treatments like subcision, TCA cross, Fractional Lasers.

For Post-Acne Erythema: I suggest Vascular lasers like V beam, Yellow lasers, Spectra/Pico Plus Gold toning.

Check out this Guide to Acne Scar Treatments and Costs for more details.

You should speak to your doctor for more information!

Hope that this helps!

Warmest regards,

Dr Justin Boey

I agree with Dr Justin that there are several issues you have to combat and as such a combination of modalities needed. Q switch is not going to be the key answer.

1) You still have some acne which should be controlled with good mix of topical and oral medications. I always firmly believe that chasing after scars is pointless IF the outbreaks are not adequately dealt it.

2) You have post acne erythema which can be dealt with using Yellow lasers or in some clinics, even the use of IPL. I don't think IPL is useless, in fact I think its a cost effective method of treating some skin conditions if properly done.

3) Icepick and some mild rolling scars can be seen. Consider TCA cross and subcision + fillers to treat these issues.

Discuss with your doctor and I am sure there are doctors out there who will be willing to spend time talking to you instead of leaving the staff to sell packages.

Hope all goes well.

Similar Questions

When is Q switch 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 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.

Photo of Human

Answered By


How effective are the various types of chemical peels for acne scars?

Medical-grade Chemical Peels are highly effective treatments for Acne Scars. It is proven that TCA Cross 70% alone can give you good to excellent improvement (> 50% improvement) of atrophic acne scars, especially severe boxcar scars. I routinely perform TCA Cross for ice pick scars and deep box acne scars. TCA Cross, which stands for Trichloroacetic acid, is a medium to deep chemical peel. There is a wide range of concentrations of TCA cross (from 35% to 100%). I usually combine this with subcision, Lasers and Rejuran injections for enhanced results in treating ice-pick scars.

Photo of Human

Answered By


Ask any health question for free

I’m not so sure about a procedure...

Ask Icon Ask a Question

Join Human

Sign up now for a free Human account to get answers from specialists in Singapore.

Sign Up

Get The Pill

Be healthier with our Bite-sized health news straight in your inbox