In short. Laser and light treatment for pigmentation uses wavelengths melanin absorbs to damage pigment while sparing surrounding tissue. Pigment type and depth determine the device: superficial lentigines suit intense pulsed light, dermal pigment such as nevus of Ota needs Q-switched or picosecond lasers, and melasma needs low settings. Diagnosis comes first, because laser destroys diagnostic evidence.
Key points
- Melanin absorbs broadly, so selective photothermolysis damages pigment while sparing surrounding tissue.
- Pulse duration and mechanism separate Q-switched, picosecond, intense pulsed light and resurfacing devices.
- Pigment depth and skin type drive device choice and settings.
- A lesion must be diagnosed first; laser can destroy melanoma evidence.
- Post-inflammatory hyperpigmentation is the commonest risk, especially in darker or tanned skin.
How does laser light clear pigment?
Different targets absorb different wavelengths of light. Melanin absorbs across a broad range that includes short, visible and near-infrared wavelengths, so a device tuned to a wavelength melanin absorbs well, fired briefly enough to confine heat to the pigment package, can damage pigment while sparing the tissue around it. This is selective photothermolysis, the basis of every pigment laser in use.
Which device suits which pigment?
| Situation | Device approach | Main caution |
|---|---|---|
| Superficial lentigo | Intense pulsed light | May clear in one or a few sessions |
| Dermal pigment such as nevus of Ota | Q-switched or picosecond laser | Many sessions; lightening often incomplete |
| Diffuse pigment with texture | Fractional or non-ablative resurfacing | Works on texture and pigment together |
| Melasma | Low settings, with topical maintenance and photoprotection | Can rebound and worsen |
| Undiagnosed or changing lesion | None until diagnosed | Laser destroys the evidence |
The classes differ in pulse duration and mechanism. Q-switched lasers deliver very short pulses that shatter pigment packages, and have long been the standard for dermal pigment such as nevus of Ota. Picosecond lasers are faster still, producing a more mechanical effect with, in principle, less heat and less surrounding damage. Intense pulsed light is not a laser but a broad-spectrum light source, useful for superficial lentigines and for the redness that accompanies sun damage. Fractional and non-ablative resurfacing devices work on texture and on diffuse pigment together.
Diagnosis comes before the device
Planning matters more than the device itself, and planning starts with diagnosis. Lasering a lesion that has not been identified is unacceptable: if a pigmented lesion is a melanoma, the treatment destroys the evidence and delays the diagnosis.
Planning the session
After diagnosis, skin type and its tendency to darken after injury, pigment depth, and whether the condition is active and inflammatory such as melasma or stable such as a lentigo all shape the plan. A test spot in an inconspicuous area is the practical check. The interval between sessions, the number of sessions and aftercare follow from those decisions.
The risks are real, not theoretical
Post-inflammatory hyperpigmentation, where the treated area darkens rather than lightens, is the most common complication and is more likely in darker skin tones, tanned skin and at aggressive settings. Hypopigmentation, blistering, textural change and scarring can occur. Clearance is often partial rather than complete, pigment can return over time, and melasma in particular can rebound and worsen after laser treatment. These are reasons for caution and planning, not for refusing treatment altogether.
What a course of treatment looks like
Most pigment laser treatment is a course, not an event. Superficial lentigines may clear in one or a few sessions. Dermal pigment such as nevus of Ota typically needs many sessions spaced weeks to months apart, with cumulative and often incomplete lightening. Melasma is handled differently again, with low settings and a strong emphasis on topical maintenance and photoprotection, precisely because it is so prone to worsening.
Strict sun avoidance before and after each session is part of the treatment, not advice around it. Tanned skin is a relative contraindication, and unprotected skin after a session is how many complications begin.
When should you pause before agreeing?
- Confirm that the lesion has been diagnosed, and never accept laser treatment for a spot that is changing, bleeding or undiagnosed.
- Ask how the settings account for your skin tone and your history of darkening after injury.
- Ask what happens if the pigment returns, darkens instead of lightening, or needs many more sessions.
Sources
- American Academy of Dermatology — laser and light therapy for pigmented lesions
- NICE — guidance on laser treatment for skin pigmentation
- British Association of Dermatologists — patient information on laser treatment
Internal links
Frequently asked questions
How do pigment lasers clear a lesion?
Melanin absorbs a broad range of wavelengths, so a device tuned to a wavelength melanin absorbs well, fired briefly enough to confine heat to the pigment package, damages pigment while sparing the tissue around it. This is selective photothermolysis, the basis of every pigment laser in use.
Why must a lesion be diagnosed before laser treatment?
Because laser treatment destroys the evidence a pathologist needs. If a pigmented lesion is a melanoma, treating it first delays the diagnosis, and every pigment laser plan at Chongqing West District Hospital therefore begins with diagnosis rather than with the device.
What are the risks of pigment laser treatment?
Post-inflammatory hyperpigmentation, where the treated area darkens rather than lightens, is the most common complication and is more likely in darker skin tones, tanned skin and at aggressive settings. Hypopigmentation, blistering, textural change and scarring can occur, and clearance is often partial.
Risks & Limitations
- Most chronic skin disease is managed rather than cured, and relapse is expected.
- Treatments typically need 8–12 weeks before response can be judged fairly.
- Topical treatment can cause irritation, dryness, peeling and photosensitivity.
- Systemic therapy may require blood monitoring and carries organ, metabolic and pregnancy risks.
- Isotretinoin in particular requires strict monitoring and pregnancy prevention.
- Pigment change is often slow and may be incomplete.
- No treatment works for everyone, and response cannot be predicted with certainty.
When to Seek Care
- A mole or lesion that changes in size, shape or colour, or starts to bleed, itch or crust.
- Fever with a widespread rash, blistering, or rash involving the eyes, mouth or genitals — seek emergency care.
- Rapidly spreading redness, swelling or pain in the skin.
- Facial swelling or difficulty breathing — possible severe reaction; seek emergency care immediately.
- New or worsening symptoms while taking a monitored medication.
References & Further Reading
- American Academy of Dermatology (AAD) — public and clinical guidance
- World Health Organization (WHO) — skin and infectious disease resources
- Chinese Medical Association, Dermatology Branch — clinical guidance
- Cochrane Library — systematic reviews in 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.