In short. The complications that should change your decision: burns and blistering, post-inflammatory pigmentation in darker skin, and the habits that cause them.

Key points

  • Complications cluster around a small number of choices: settings selected for the device rather than for the skin in front of it, overlapping passes over the same area, treatment of tanned skin, and a course that continues after the skin has already reacted.
  • None of these are accidents of the technology.
  • They are decisions, and they are the ones worth asking about.

Every treatment has a list of possible complications, and the useful question is which of them are common enough to change your decision. Here there are three: burns and blistering, post-inflammatory hyperpigmentation, and scarring. All three are uncommon in well-assessed skin treated conservatively, and all three become considerably more likely when a session is pushed.

Burns and blistering

A burn is not a rare accident that happens to careless clinics; it is a predictable consequence of delivering more light than the skin can absorb safely. It is more likely on freshly tanned skin, on darker skin treated with settings designed for lighter skin, when the handpiece overlaps the same patch repeatedly, and when a test spot has been skipped. The result ranges from a superficial burn that settles within a week to blistering that can leave a mark.

Pigment change, which is the commoner problem

Post-inflammatory hyperpigmentation — the skin reacting to injury by producing more pigment — is the complication patients are least often warned about. It is more common and more stubborn in darker skin, it can appear weeks after the session rather than immediately, and it can take months to settle. In some patients it is darker than the original problem was.

Less commonly, treated skin can lose pigment rather than gain it, leaving pale patches that are difficult to treat. Permanent colour change of either kind is uncommon, and it is the reason a test spot and a conservative first session exist.

The decisions that cause trouble

Complications cluster around a small number of choices: settings selected for the device rather than for the skin in front of it, overlapping passes over the same area, treatment of tanned skin, and a course that continues after the skin has already reacted. None of these are accidents of the technology. They are decisions, and they are the ones worth asking about.

Scarring, and the eyes

Scarring after this treatment is rare, and usually follows a burn or an infection in treated skin rather than occurring on its own. It is more likely in patients with a tendency to raised scars, which is one of the reasons that history is asked about. Eye protection is not optional: the light is bright enough to injure the eye, and shields are worn by everyone in the room for that reason.

Seek review promptly if

  • You have blistering, severe pain, or a wound that is weeping or crusting in the days after a session.
  • Your skin is becoming darker in the treated area and not settling, or is showing pale patches.
  • You are offered further sessions on skin that has not recovered, or with settings unchanged despite a reaction.

None of this makes IPL a dangerous treatment. It makes it a treatment with a real risk profile that depends heavily on who assesses you and how the first session is conducted. A conservative first session is not timidity; it is how the information you need is gathered safely.

Related reading

Frequently asked questions

How likely is post-inflammatory hyperpigmentation?

It is uncommon in lighter skin treated conservatively and considerably more common in darker skin, where it can also be more stubborn. It may appear weeks after the session and can take months to settle, which is why a conservative first session and a test spot matter.

Can IPL cause a scar?

Scarring is rare and usually follows a burn or an infection in treated skin rather than occurring on its own. A history of raised scarring is one of the reasons a clinic may decline to treat you, and it should be discussed before the first session.

How are the settings chosen for my skin?

From an assessment of your skin type, not from a number you can bring with you. What you can reasonably ask is how the settings were chosen, whether a test spot was done, and what would make the clinic reduce them.

Risks & Limitations

  • Pigmented spots darken before they flake away; that darkening is expected and is not a burn — blistering, crusting or increasing pain is.
  • Post-inflammatory hyperpigmentation is a real risk, is more common and more stubborn in darker skin, and can take months to settle.
  • Burns and blistering occur, particularly on tanned skin, with settings chosen for the device rather than the skin, and where passes overlap the same area.
  • Treated skin can occasionally lose pigment rather than gain it, leaving pale patches that are difficult to treat.
  • Scarring is rare and usually follows a burn or an infection in treated skin; a tendency to raised scarring is assessed before treatment.
  • No result is permanent. Pigment returns as the skin continues to produce it, and sun exposure is the main thing that decides how quickly.
  • The treatment changes colour, not contour. It does not tighten, lift, fill or remove wrinkles.
  • Eye protection is worn by everyone in the room, because the light can injure the eye.
  • Individual response varies; no outcome can be guaranteed.

When to Seek Care

  • Blistering, severe or increasing pain, or a wound that is weeping or crusting after a session.
  • Skin in the treated area becoming markedly darker over the following weeks rather than fading, or developing pale patches.
  • A cold sore, a spreading rash or a fever after treatment.
  • Any pigmented spot that is new, changing in size, shape or colour, or that looks different from the others on your skin.
  • Frequent severe flushing with other symptoms, which needs a medical assessment rather than a cosmetic plan.

References & Further Reading

  • American Academy of Dermatology (AAD) — patient information on laser, light and pigment conditions of the skin
  • British Association of Dermatologists (BAD) — patient information on laser and light treatment
  • U.S. Food and Drug Administration (FDA) — consumer information on laser and light-based devices
  • Cochrane Library — systematic reviews of laser and light treatment for pigment and vascular skin concerns

Medically reviewed by Ke He, MD (何锞), Deputy Director & Head of Skin & Laser Aesthetics. Last reviewed: 19 September 2026.

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.