In short. Skin type, recent sun, medicines, current products and previous treatments change what is safe. None of them can be read from a photograph.

Key points

  • Skin type, recent sun, medicines, current products and previous treatments together decide what is safe to do now and at what settings.
  • A plan made without them is a plan made in the dark, and the risk of the treatment is carried whether or not the skin was ready for it.

Two people with the same mark on the same part of the face are not necessarily candidates for the same treatment. What decides the plan is not the mark alone but how the skin around it behaves, and that is established by a history and an examination rather than by a photograph.

How your skin behaves after injury

Some skin produces extra pigment after injury, some loses it, and some does neither. A history of a mark that darkened after a cut, a burn, a spot or an earlier procedure is the single most useful thing an assessment can establish, because it predicts how the skin is likely to respond to a treatment that injures it deliberately. This is why a test spot on a small area, reviewed before a full course, is a reasonable first step rather than a delay.

Skin type, thickness and oiliness

Skin varies in how much pigment it carries, how thick the surface layer is, and how active the oil glands are. Those three findings decide how much energy a device can safely deliver, how the skin is prepared beforehand, and how long the interval between sessions should be. They are felt and looked at in daylight, and they are not always obvious from a photograph taken on a phone.

Sun exposure, medicines and what you are using now

Recent sun exposure leaves pigment cells active and the surface repairing. Some medicines and some prescribed skin products make the skin more sensitive to light, and a course begun without that information risks a burn or a mark. What you apply at home matters too: a routine built on strong exfoliating acids changes how the skin tolerates a peel or a resurfacing treatment, and it is adjusted before the course rather than during it.

What previous treatments did, and what they did not

A history of previous treatments is a record of how this particular skin responded, which is more useful than any general expectation. It also establishes what has already been tried, so that the same approach is not repeated with the same result. Where a course produced no change, the useful question is whether it was aimed at the wrong structure, delivered at the wrong depth, or given for too few sessions.

The assessment is the safety step

Skin type, recent sun, medicines, current products and previous treatments together decide what is safe to do now and at what settings. A plan made without them is a plan made in the dark, and the risk of the treatment is carried whether or not the skin was ready for it.

Findings that defer a treatment

  • A mole or lesion that is changing, bleeding or not healing is assessed before anything else.
  • Active infection, a cold sore, or skin that is broken, blistered or raw in the area.
  • A recent sunburn or a tan, until the skin has settled and the colour has faded.

Related reading

Frequently asked questions

Why does a photograph not tell the practitioner enough?

A photograph records colour and shape, and it does not record how skin behaves. It does not show how easily the skin marks, whether it stings under a product, how thick the surface is, whether vessels blanch under pressure, or how the skin responded to a previous treatment. Those are the findings that decide settings and staging, and they come from an examination in daylight and from your history.

Does a recent holiday in the sun really change the plan?

It changes what is safe to do now. Skin that has been tanned or recently burned has pigment cells that are already active and a surface that is still repairing, so a treatment that would be routine on settled skin carries a higher risk of an uneven result or of a mark afterwards. The usual approach is to wait until the tan has faded and the barrier has settled, rather than to proceed and hope.

Which parts of my skin history does the assessment need?

A list of what you currently use on your skin, including anything active or prescribed; the medicines you take and any allergies; any previous aesthetic treatments and how your skin responded; and whether you have ever developed a dark or light mark after a cut, a burn or a procedure. That last question is one of the most useful things you can tell a practitioner, and it is not visible on your skin.

Risks & Limitations

  • Every skin treatment carries risk, and no result can be promised.
  • Pigment often returns after treatment, especially after sun exposure, because the cells that produce it remain in place.
  • Skin that marks easily after injury can darken or lighten after a treatment, which is why a test spot is used to judge the risk.
  • Results are judged over months rather than weeks, and maintenance is often needed to hold them.

When to Seek Care

  • A mole that is changing in size, shape or colour, or one that bleeds, itches or crusts.
  • A spot, sore or crusted patch that has not healed over a few weeks.
  • A rash with fever, joint pain, mouth ulcers or blistering, or one that involves the eyes or mouth.
  • A treated area that becomes increasingly painful, red, hot and swollen, which may be an infection.

References & Further Reading

  • American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
  • National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
  • Cochrane Library — systematic reviews
  • Chinese Medical Association Plastic Surgery Branch — clinical guidance

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.