What a laser course actually involves

Melanin is the target, and melanin is also in the epidermis. The whole craft is delivering heat to the follicle without depositing it in the skin above.

For lighter skin with dark hair, a 755 nm alexandrite is strongly absorbed and highly efficient. As skin gets deeper, that same strong absorption becomes the hazard, and the 1064 nm Nd:YAG becomes the correct tool: less avidly absorbed by melanin, penetrating further, safer in Fitzpatrick IV to VI, and requiring longer pulse durations and careful cooling. An 810 nm diode sits between the two.

A clinic with one wavelength will treat everyone with it. That is the practical reason we ask about background and sun exposure at assessment, and the reason a course designed for one person is not a template for another.

Intense pulsed light for sun-induced pigment and redness: three to five sessions, three to four weeks apart. It is the wrong tool for melasma, and using it there is the most common way we see melasma made worse.

Non-ablative fractional resurfacing for texture, scarring and tone: three to five sessions, four to six weeks apart, with a genuine cumulative effect and a review at three months, which is when the collagen response has actually happened rather than when it feels as though it should have.

Ablative fractional resurfacing: fewer sessions, considerably more downtime, and a different consent conversation altogether.

• Hair reduction. Redness and small raised bumps around each follicle for a few hours, occasionally a day. Makeup the same day if needed. Treated hairs shed over one to three weeks, which is regularly mistaken for regrowth.
• Pigment. Treated spots darken within a day to look like coffee grounds, then flake away over roughly seven to ten days. They must not be picked.
• Non-ablative fractional. Swelling on days one and two, a sandpaper texture and a bronzed look for three to five days, makeup usually possible from day three.
• Ablative fractional. Seven to fourteen days of visible healing and several weeks of residual pink.

• Recently tanned skin, including self-tanner. Two weeks clear of both, minimum, and longer after a real holiday.
• Isotretinoin currently or recently. The traditional six-month rule is being revised by newer evidence; we remain conservative about it.
• Photosensitising medication — some antibiotics, some diuretics, oral retinoids, St John's wort.
• Pregnancy. Not because harm is established, but because it is not, and this is elective.
• A history of cold sores, without antiviral prophylaxis, for anything near the mouth.
• Melasma, for most pigment-targeted light. Heat is a trigger, and the standard tools make it worse.
• A tendency to keloid or hypertrophic scarring, which changes what is appropriate and sometimes rules it out.
• Gold-containing medication, and permanent cosmetic tattooing inside the treatment field.

Six sessions of leg hair reduction at ten-week intervals is a year, plus the patch test and a review. That is the honest shape of it, and it is one of the reasons we start most courses in the autumn, when skin has not been tanned and the following months are largely indoors.

Missing appointments does not simply postpone the end date. For hair, it lets the growth cycles drift out of step with the schedule, and the last two sessions do less than they should have. Booking the whole course at the outset is not an administrative preference — it is the difference between finishing and drifting.

There is more on the seasonal reasoning in why we start laser courses in the autumn.