In short. Both depend on contrast between hair and skin, and the assessment of hair colour and skin type decides who is likely to respond and who will not.
Key points
- Dark hair on lighter skin is the finding that predicts a response, and it predicts it for both instruments.
- That is why the assessment of hair colour and skin type comes first, and why the choice of instrument comes after it.
These two options are usually discussed as though the instrument decided the outcome. It does not. What predicts a response is the contrast between the colour of the hair and the colour of the skin around it, and that finding is the same for both instruments.
Who responds
A patient with dark, coarse hair on lighter skin. Coarse hair responds better than fine hair, because there is more pigment in it and the follicle is larger. Lighter skin provides the contrast the treatment depends on. No recent sun exposure and no medicine that makes the skin sensitive to light are part of the same picture.
Who responds poorly
A patient with light, grey, red or white hair. Those colours contain little of the pigment the treatment depends on, so there is nothing for the light to act on, and that is equally true of both instruments. A patient with fine dark hair may also respond less than they expect, for the same reason. Where the hair is the result of a hormonal condition, that condition is part of the assessment, because treating the hair without it is a partial answer.
One finding, both options
Dark hair on lighter skin is the finding that predicts a response, and it predicts it for both instruments. That is why the assessment of hair colour and skin type comes first, and why the choice of instrument comes after it.
Darker skin, and the risk that comes with it
Both options can be used on darker skin, and both carry a higher risk there, because the pigment in the skin absorbs some of the energy that was meant for the hair. That narrows the margin between a useful setting and a damaging one, and it makes the choice of setting a matter of judgement rather than a formula. It is also why the treatment is often started more cautiously on darker skin, and why the skin is watched between sessions.
What the assessment adds
The assessment establishes the colour and coarseness of the hair, the skin type and how it tans or burns, any previous light treatment and how the skin responded to it, the medicines being taken, and the area to be treated. Those findings decide whether either option is suitable, which one is proposed, and how the course is planned.
Findings that make either option unsuitable
- White, grey, red or very light hair, which does not have the pigment either option depends on.
- A medicine that makes the skin sensitive to light, taken without that being discussed first.
- An active skin condition or infection in the treated area, or a fresh tan, which is treated or waited out first.
Candidacy here is a finding rather than a preference, and it is the same finding on both sides of the comparison. A patient who knows what was found will know why one instrument was proposed, or why no course was offered.
Frequently asked questions
Who is most likely to respond to either option?
A patient with dark, coarse hair on lighter skin, with no recent sun exposure and no medicine that makes the skin light-sensitive. That description applies to both instruments, and it is the finding that predicts a response more than anything about the instrument itself. Coarse hair responds better than fine hair.
Who is unlikely to respond?
A patient with light, grey, red or white hair, because both options depend on pigment in the hair to carry the light into the follicle. A patient whose hair is fine and dark may respond less than expected for the same reason. And a patient whose hair is the result of a hormonal condition may need that assessed, because treating the hair without it is a partial answer.
Can I be treated if my skin is darker?
Both options can be used, and both carry a higher risk of burns and pigment change on darker skin, because the pigment in the skin competes with the pigment in the hair for the energy being delivered. That is why the settings are chosen for the skin in front of the clinician and why a recent tan is a reason to postpone rather than to proceed.
Risks & Limitations
- No result can be guaranteed, and hair reduction is not the same as permanent hair removal.
- Burns, blistering and pigment change are possible with both options, and are more likely when the settings do not match the skin or the skin has been tanned recently.
- Hair returns over the months after a course, and both options need maintenance rather than one course.
- Neither option works well on light, grey, red or white hair, because both depend on pigment in the hair.
When to Seek Care
- A blister, or skin that is weeping or breaking down in the treated area.
- Pain that is increasing rather than settling, or redness that is spreading.
- A change in skin colour — lighter or darker — that is spreading rather than fading.
- Any reaction in the treated area that is worsening rather than settling in the days after a session.
References & Further Reading
- American Academy of Dermatology (AAD) — hair removal and laser 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
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.