Aesthetics

Laser hair removal: sessions, skin types and results

Laser and intense pulsed light treatment thins hair rather than deleting it, which is why the honest term is long term reduction and not removal. A first session takes roughly 10 to 25 percent of the hair in the treated patch, a minimum course runs 4 to 6 sessions spaced 4 to 6 weeks apart, and the pooled trial evidence, a Cochrane review from 2006 of 11 randomised controlled trials with 444 participants, found about 50 percent reduction up to 6 months after treatment with 755 nm and 810 nm devices. Maintenance appointments once every 6 to 12 months belong in the plan from the start.

What the light is aiming at

Every hair removal device in a clinic works on one principle, selective photothermolysis. Light of a chosen wavelength is absorbed by a pigment, that pigment heats, and the heat damages the structure around it before it spreads further. In hair removal the pigment is melanin, which absorbs light between 300 and 1200 nm, and the devices built for the job emit between 600 and 1200 nm.

Melanin sits in the hair shaft and in the matrix cells at the base in far higher concentration than in the follicle wall. The shaft takes the energy and passes the heat outwards to the matrix and to the stem cells in the bulge. That mechanism sets the two limits everyone meets. Hair without pigment has nothing to absorb the beam, and pigment in the epidermis competes for the same light, which weakens the effect on the follicle and puts energy where it can burn.

It also explains why you shave before an appointment rather than wax. Plucking and waxing pull out the target, so reference guidance asks for 6 weeks without epilation beforehand, and one clinic protocol published in 2024 asks for 1 month without waxing or threading. The area is shaved close enough to leave slight stubble, enough shaft to absorb the light and not so much that the energy is spent above the skin.

Why sessions are spaced 4 to 6 weeks apart

Hair does not grow continuously. Each follicle cycles through a growth phase, a short regression and a rest, and the matrix is only sensitive to the laser during the growth phase, anagen. Any single appointment reaches only the follicles growing that week and misses the rest. Spacing the sessions is how the others are caught as they come back.

The minimum course in the reference literature is 4 to 6 sessions spaced 4 to 6 weeks apart. Dermatology patient information puts most courses at 2 to 6 treatments taken once every 4 to 6 weeks, and the 2024 clinic protocol books the review for the next session at the same 4 to 6 weeks. Fine vellus hair returns afterwards, so maintenance treatments once every 6 to 12 months are part of the arrangement, not a sign that something failed.

Areas differ. Underarm and pubic hair respond better than hair on the arms, legs and chest, and hormonal status is one of the listed factors that decides the outcome, which is why unwanted growth driven by hormones is investigated before it is treated. Appointment length follows the area as well: an upper lip takes minutes, a back or a pair of legs can run past an hour, and a numbing gel, where one is used, needs 30 to 60 minutes before the first pulse.

What the trials actually report

Dermatology patient information tells people to expect a 10 to 25 percent reduction in hair after the first treatment, with most patients needing 2 to 6 treatments, several months or even years without visible hair afterwards, and regrowth that tends to be finer and lighter in colour.

The trial evidence is thinner than the advertising. A Cochrane review published in 2006 pooled 11 randomised controlled trials with 444 participants, none of high methodological quality, and found a short term effect of about 50 percent hair reduction up to 6 months after treatment with alexandrite and diode devices. For ruby, Nd:YAG and intense pulsed light the reviewers found little evidence of an effect. Long term hair removal was not documented with any treatment.

That is the honest frame. About half the hair gone at 6 months is a real result and a modest one, follow up in most of those trials stopped there, and the adverse effects the reviewers saw, pain, redness, swelling, burned hairs and pigment changes, were reported infrequently rather than measured systematically. Photographs taken in a clinic before and after a course are not evidence, and a percentage quoted without the follow up period attached is not either.

Wavelength, phototype and burn risk

Wavelength is the decision that matters most on deeper skin, because longer wavelengths reach further down and are absorbed less by the melanin sitting in the epidermis. A 694 nm ruby and a 755 nm alexandrite are described for Fitzpatrick types 1 to 3. An 810 nm diode penetrates deeper, delivers its fluence with less epidermal damage and is used up to type 5. A 1064 nm Nd:YAG absorbs least in melanin and is the one described across all 6 types. Intense pulsed light is not a laser but a filtered flashlamp emitting 500 to 1200 nm, with a larger spot, a lower price and, in the same reference, less effect than a true laser.

Put a short wavelength on type 5 or 6 skin and the epidermis takes energy meant for the follicle. Redness, pain and a burning sensation are the common outcomes, and swelling around the follicles is expected rather than a complication. The more serious list runs to blistering, crusting, loss or gain of pigment, purpura and sometimes scarring, and a change in skin colour does not always reverse. The controls are wavelength, fluence, spot size and cooling, plus an operator who treats skin like yours every week.

Two further risks belong in the consent conversation. Paradoxical hypertrichosis, denser hair at or around a treated area, is rare but is reported more often in skin type 3 and with intense pulsed light systems. The eye is vulnerable to a stray beam, so every person in the room, patient, operator and assistant, wears eyewear matched to that wavelength, and reflective or metallic objects are kept away from the field.

Who may hold the device and what stops the appointment

In England the question of who may hold the handpiece is still open. The 2023 consultation on licensing non-surgical cosmetic procedures proposed non-ablative laser hair removal and intense pulsed light treatments for the green tier, the lowest risk group, where any practitioner is eligible provided they meet agreed standards. The same scheme proposed a minimum age of 18 unless a doctor approves the procedure and a healthcare professional carries it out. That consultation closed on 28 October 2023, the response of 7 August 2025 left the categories unsettled and set no date, and no licence is required yet, so the questions you ask still do most of the regulating.

The reference literature is blunt about that gap. Nurses, dermatologists, plastic surgeons, primary care providers and cosmetic surgeons all perform the treatment, oversight is lacking, complications are common and patients are often given expectations nobody can meet. Patient information from a dermatology body says the same in plainer words, that burns, lasting changes in skin colour and scars can follow treatment in inexperienced hands, and advises choosing a board certified dermatologist. Ask how many people with your phototype the operator treats in a normal week, and on which device.

Some answers stop or postpone the session. The 2024 clinic protocol screens for pregnancy and breastfeeding, for active viral, bacterial or fungal infection at the site, for a history of cold sores, for a tendency to scar or form keloids, for anticoagulants and for photosensitising medication of any kind, herbal and homeopathic preparations included. A fresh tan from a holiday or a lamp is a reason to wait, salon treatments in the past 1 to 2 weeks are asked about, waxing and threading stop 1 month before, and topical retinoids and glycolic acid stop 2 days before. Tattoos, moles and eyebrows inside the field are covered with opaque tape so the light cannot reach them, consent is signed again before every repeat session, and direct sun is avoided for at least 1 week afterwards, with sunscreen reapplied to the treated area every 2 to 3 hours and a moisturiser at night if the skin is dry. Our guide on how much sunscreen the face needs covers the amount, and the Results Timeline sets out when a course shows.

What to settle before the first session

Frequently asked

How many sessions will I need?

Reference guidance sets a minimum of 4 to 6 sessions spaced 4 to 6 weeks apart, and dermatology patient information puts most courses at 2 to 6 treatments once every 4 to 6 weeks. Maintenance treatments once every 6 to 12 months are usually needed after that.

Is laser hair removal permanent?

No. The procedure delivers long term reduction rather than removal, and a Cochrane review published in 2006 pooled 11 trials with 444 participants and found no long term hair removal documented with any device, only about 50 percent reduction up to 6 months with alexandrite and diode treatment.

Does it work on darker skin?

Yes, with the right wavelength. A 1064 nm Nd:YAG is described across all 6 Fitzpatrick types and an 810 nm diode up to type 5, while 694 nm and 755 nm devices are described for types 1 to 3 and carry a higher risk of burns, blistering and pigment change on types 5 and 6.

Why does grey or blonde hair respond poorly?

The light is absorbed by melanin in the hair shaft, so a follicle with little or no pigment gives the beam almost nothing to heat. White, grey and most blonde hair therefore responds poorly whatever the device between 694 and 1064 nm.

What are the side effects?

Redness, pain, a burning sensation and swelling around the follicles are expected, and minor effects usually settle within 1 to 3 days. Blistering, crusting, purpura, loss or gain of pigment, cold sore outbreaks and scarring are less common, and paradoxical hypertrichosis, denser hair at the treated site, is rare but reported more often in skin type 3 and with intense pulsed light.

Can I have it during pregnancy?

Pregnancy and breastfeeding sit on the standard pre-treatment questionnaire and are a reason to postpone. There is no evidence of benefit that would justify treating during pregnancy, and hair growth driven by hormones may change on its own afterwards.

Sources

• Laser Hair Removal, StatPearls · Peer reviewed reference chapter hosted by the National Library of Medicine, updated 25 July 2023; source for selective photothermolysis, melanin absorption from 300 to 1200 nm, the 694, 755, 810 and 1064 nm devices with the Fitzpatrick types described for each, intense pulsed light at 500 to 1200 nm, the minimum of 4 to 6 sessions at 4 to 6 week intervals, maintenance every 6 to 12 months, anagen sensitivity, 6 weeks without epilation beforehand, eye protection, the complication list and paradoxical hypertrichosis in skin type 3 and with intense pulsed light.
• Laser and photo epilation for unwanted hair growth, Cochrane plain language summary · Cochrane systematic review summary, published 18 October 2006, which is the age of the pooled evidence quoted here; source for the 11 randomised controlled trials with 444 participants, none of high methodological quality, about 50 percent hair reduction up to 6 months with alexandrite and diode devices, little evidence for ruby, Nd:YAG and intense pulsed light, the absence of documented long term removal and the infrequently reported adverse effects.
• Laser hair removal, frequently asked questions · American Academy of Dermatology patient information; source for the 10 to 25 percent reduction after the first treatment, 2 to 6 treatments, sessions once every 4 to 6 weeks, minor side effects lasting 1 to 3 days, the rarer blistering, infection, scarring and colour change, numbing gel needing 30 to 60 minutes, eye protection for everyone in the room and the warning about inexperienced hands.
• Standard operating protocol for utilizing energy-based devices in aesthetic practice · Journal of Cosmetic Dermatology protocol paper from 2024 in PubMed Central; source for the pre-treatment screening for pregnancy, breastfeeding, active infection, cold sores, keloid tendency, anticoagulants and photosensitising medication, for waxing and threading stopping 1 month before, active creams 2 days before, covering tattoos, moles and eyebrows with opaque tape, consent before every repeat session, the review at 4 to 6 weeks, the follow up calls on day 1 and day 5, sun avoidance for at least 1 week afterwards, sunscreen every 2 to 3 hours on the treated area and a moisturiser at night in case of dryness.
• The licensing of non-surgical cosmetic procedures in England, consultation document · Department of Health and Social Care consultation that closed on 28 October 2023 and now carries the consultation outcome, updated 7 August 2025; source for non-ablative laser hair removal and intense pulsed light being proposed for the green tier open to any practitioner meeting agreed standards, for the proposed minimum age of 18 unless a doctor approves and a healthcare professional performs the procedure, and for the response leaving the placement of individual procedures to further work with no start date set.

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This guide is for general information. It does not replace advice from a dermatologist, physician or qualified practitioner, or an examination.