In short. Burns, post-inflammatory pigmentation, scarring, and infection after laser treatment, the aftercare that limits them, and the warning signs that need urgent care.
Key points
- Keep the treated area clean and covered with the recommended ointment until the surface has closed.
- Cool it gently if it feels hot.
- Do not pick, scrub, exfoliate, or peel the healing skin, and do not apply active acids or retinoids until cleared.
Laser and energy-based treatment is generally well tolerated, but it is not risk-free, and the risks are worth understanding before consent rather than after a complication. Most are manageable when recognised early; a few need medical attention the same day.
Burns and blistering
A burn occurs when more energy reaches the skin than it can absorb safely. It may follow an error in settings, an unrecognised recent tan, a cooling failure, overlapping passes, or simply skin that responded atypically. Superficial burns usually heal with careful wound care, but deeper burns can leave lasting pigment change or a scar. Blistering, severe pain that is not settling, or a break in the skin after a session should be assessed rather than managed at home.
Post-inflammatory pigmentation
The most common adverse outcome is darkening of the treated area, known as post-inflammatory hyperpigmentation. It is more frequent in darker skin types, after sun exposure during healing, and after treatments that were too aggressive. It usually fades over months with photoprotection and appropriate topical care, although it can persist. Less commonly, pigment is lost rather than gained, producing pale patches that are considerably harder to treat.
Scarring and infection
Scarring after laser treatment is uncommon but real, and the risk rises with deep ablation, infection during healing, and an individual tendency to hypertrophic or keloid scarring. Infection typically presents as increasing redness, warmth, swelling, pain, or discharge rather than as the expected post-treatment inflammation. Reactivation of cold sores is a particular risk after resurfacing in anyone with a history of the virus, which is why antiviral cover is often prescribed.
Aftercare that actually matters
Keep the treated area clean and covered with the recommended ointment until the surface has closed. Cool it gently if it feels hot. Do not pick, scrub, exfoliate, or peel the healing skin, and do not apply active acids or retinoids until cleared. Protect it from the sun completely — broad-spectrum sunscreen, hat, and shade — because sun exposure during healing is the single largest contributor to pigment problems. Avoid saunas, swimming, and strenuous exercise for a few days.
When to seek urgent care
Contact the treating service, or seek urgent medical attention, if you develop blistering or a break in the skin, pain that worsens rather than settles, spreading redness or warmth, fever, pus or foul discharge, a cold sore outbreak, or any change in vision after treatment near the eyes. Early review of these signs is straightforward; delayed review is where permanent problems begin.
Seek medical review promptly
- Blistering, broken skin, or pain that is increasing instead of easing in the days after treatment.
- Spreading redness, warmth, swelling, fever, or discharge from the treated area, suggesting infection.
- Any change in vision, or eye pain, after treatment performed near the eyes.
Frequently asked questions
What causes a burn during laser treatment?
More energy reaching the skin than it can absorb safely. That may follow an error in settings, an unrecognised recent tan, a cooling failure, overlapping passes, or simply skin that responded atypically. Superficial burns usually heal with careful wound care, but deeper burns can leave lasting change.
What is the most common adverse outcome after laser?
Post-inflammatory hyperpigmentation, a darkening of the treated area. It is more frequent in darker skin types, after sun exposure during healing, and after treatments that were too aggressive. It usually fades over months with photoprotection and appropriate topical care, though it can persist.
What aftercare limits laser complications?
Keep the area clean and covered with the recommended ointment until the surface has closed, cool it gently if hot, and do not pick, scrub, or exfoliate healing skin. Protect it completely from the sun, since sun exposure during healing is the largest contributor to pigment problems.
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.