Published 20 October 2026 · Reviewed by Dr Sin Yong
Underarm laser hair removal heats coarse, dark armpit hair in the follicle with a long-pulsed laser so that regrowth is reduced over a staged course. The underarm is set differently from the arm beside it: the skin is usually a shade darker, the hair is dense, and shaving, deodorant and friction all irritate it. Dr Sin Yong chooses the wavelength for the fold itself, and every session is doctor-performed.
Short answerThe underarm is one of the commonest areas requested and one of the most forgiving targets, because the hair is coarse and dark. The skin, though, is often darker than elsewhere, so the choice usually moves toward 1064 nm Nd:YAG or conservative 755 nm settings with close cooling. Hair removal does not lighten dark underarms; that is assessed as a separate concern.
Why the underarm is set differently from the rest of the body
The armpit is a fold, and a fold behaves differently from a flat surface. The skin there is thinner than on the arm, warmer, moister, and in most people a shade or two darker, partly from friction and partly from the same shaving and deodorant habits that bring people to ask about it. The hair is terminal, coarse and dense, and it is dark in almost everyone in Singapore regardless of ethnicity.
Illustrative image — not a patient.
Those two facts pull in opposite directions for a laser. Coarse dark hair is an excellent target: there is plenty of melanin in the shaft to absorb energy and conduct heat to the follicle. But darker skin around the follicle competes for the same energy, and the thin skin of the fold has less margin before it blisters or leaves a mark. The underarm therefore needs its own assessment rather than the settings used on the forearm a few centimetres away. The principles behind that assessment are on the main laser hair removal page; what follows is specific to the armpit.
The fold also carries the after-effects of what people do to it. Shaving rash, ingrown hairs, folliculitis from a blunt razor, deodorant irritation and the small cuts that come with shaving a concave surface are all common findings at the first visit, and any of them is allowed to settle before a pulse is delivered. Inflamed skin absorbs more energy and marks more readily, so treating through it is a false economy.
Which wavelength for underarm skin: 755 nm or 1064 nm
The platform used here carries both a long-pulsed 755 nm alexandrite and a 1064 nm Nd:YAG, and the choice for the underarm follows the skin of the fold, not the skin type written on the body chart. A person whose forearms are Fitzpatrick III can have underarms that behave like IV, and the wavelength follows the darker reading.
755 nm is strongly absorbed by melanin, which makes it effective on hair but less tolerant of pigment in the skin. On a lighter underarm it is used at conservative settings with close attention to cooling. 1064 nm is less readily absorbed by melanin in the upper skin and penetrates deeper, so more energy reaches the follicle rather than being taken up on the way through. That is why it is the usual choice for Fitzpatrick IV to VI and for an underarm that is naturally darker than the surrounding skin, and why reviews of laser hair removal in darker skin consistently point to the long-pulsed Nd:YAG as the wavelength with the wider safety margin there.
Underarm finding
Wavelength usually considered
Why
Light underarm skin, dark coarse hair
755 nm alexandrite, conservative settings
High contrast between hair and skin; strong melanin absorption works for you
Underarm darker than the arm, Fitzpatrick III
1064 nm, or 755 nm at lower settings
The fold is read as a darker zone; cooling matters most here
Fitzpatrick IV to VI
1064 nm Nd:YAG
Less surface absorption, deeper penetration, lower pigment-change risk
Recent tan, self-tan or sunburn on the arms
Deferred, or 1064 nm
Extra surface melanin shifts the balance toward epidermal injury
Active shaving rash or folliculitis
Deferred until settled
Inflamed skin absorbs more energy and marks more readily
Epidermal cooling runs with every pulse, and because the underarm is a concave surface the skin is held flat so that the cooled tip and the beam sit square to it. Neither wavelength is better in the abstract; they answer different skin, and the comparison between the two and the diode lasers used elsewhere is on diode vs alexandrite vs Nd:YAG.
“Hair removal clears the stubble shadow, not the pigment. If the underarm is dark, I name the cause first, because a laser aimed at hair will not fix it.”
Dr Sin YongOn underarm laser hair removal
Dark underarms and ingrown hairs: what laser hair removal does and does not change
Two concerns come to the same consultation so often that they are worth separating. The first is ingrown hair. Shaving cuts a coarse hair at an angle, and as it regrows the sharp tip can curl back into the skin or grow out sideways under the surface, producing a tender bump and sometimes a pustule. Reducing the number and thickness of regrowing hairs reduces the amount of shaving, and that is the mechanism by which laser hair reduction helps ingrown hairs rather than any direct effect on the bumps themselves. Inflamed or infected bumps are settled first, and where bumps persist the cause is examined, since folliculitis and other conditions can look similar.
The second is underarm darkening. People often expect laser hair removal to lighten the armpit, and it does not. The darkening has several causes: friction, the shadow of hair stubs under the skin, post-inflammatory pigment from years of shaving or deodorant irritation, and in some people a genuine thickening and pigmentation of the skin that points to a metabolic cause. Removing the stubs removes the grey shadow, which some people read as lightening, but the pigment in the skin is a separate problem with its own assessment on the dark underarms treatment page and its causes set out under dark underarms.
How the two are planned together
Hair reduction is planned first where shaving irritation is driving the pigment, because continuing to shave an area being treated for pigment undoes the work
Pigment is assessed separately, with the cause named before any treatment for it is proposed
The two are not treated in the same session on the same skin; the fold is allowed to settle between them
Excessive sweating is a third, separate concern and has its own page under hyperhidrosis
Saying this plainly at consultation matters, because a person who expects a lighter underarm from hair removal will be disappointed by a result that is otherwise exactly what the laser was meant to do.
What decides the number of visits for the underarm
Laser hair removal is staged across visits because only follicles in their active growth phase respond at any one time, and at any moment a proportion of underarm follicles are resting. The underarm has a relatively short cycle compared with the scalp, and the proportion of follicles in the growth phase at a given time is one of the things that sets the spacing between visits. Nobody is given a count at this clinic, because the number that is right for one armpit is wrong for another. What decides it is set out in full on what decides the number of sessions; for the underarm the main variables are:
Hair cycle: the next visit is timed to when a fresh cohort of follicles has entered growth, which is assessed rather than fixed
Colour contrast: dark hair on lighter skin responds at settings that darker skin cannot be given, so a darker underarm may be treated more conservatively and over more visits
Hair density and coarseness: dense coarse hair responds well but sheds in stages, and later visits are set for the finer hair that remains
Previous treatment: IPL or diode elsewhere changes what hair is left and how it responds; bring the records
Hormones: pregnancy, polycystic ovary syndrome and some medicines change underarm hair over time, and new growth after a course is not a failure of the earlier treatment
Regulators describe what lasers achieve as a long-term, stable reduction in the number of hairs that regrow, not an absence. Hair that does return is usually finer and lighter, which is why later visits in a course behave differently from early ones, and why the plan is reviewed at each visit rather than agreed as a fixed package.
How underarm laser hair removal is done here
Treatment runs on the R2 Glow platform, a long-pulsed laser carrying both 755 nm alexandrite and 1064 nm Nd:YAG, and every session is performed by Dr Sin Yong after examining the fold on the day. The underarm is shaved beforehand, not waxed, plucked or epilated, so that the hair shaft and its pigment stay in the follicle for the laser to find; shaving a day or two ahead is ideal, because a freshly shaved fold is often nicked and raw.
Deodorant and antiperspirant are washed off before treatment. Some antiperspirants leave aluminium salts on the surface that are better removed, and fragranced products on freshly lasered skin sting. The skin is checked for irritation, cuts, folliculitis and the darker patches described above, protective eyewear is fitted, and the arm is positioned so that the fold is flattened. Settings are chosen for the fold itself; where the underarm is markedly darker than the surrounding skin, a test patch is treated and reviewed before the full area.
Underarms are commonly planned together with a brazilian and the legs in the same consultation, but each area is set independently, because the skin and the hair differ from one to the next. Men asking about the underarm are assessed on the same principles. Pregnancy, an active infection or cold sore, recent isotretinoin, photosensitising medicines and a recent tan are reasons to wait, and the full list is on the owner page under who should not have laser hair removal.
Aftercare for the underarm: deodorant, shaving and sweat
Afterwards the fold feels warm and looks red, with small raised bumps around the follicles that settle on their own. A cool compress helps. For the rest of the day the area is kept cool and dry: no hot showers, saunas or vigorous exercise, no tight or synthetic sleeves rubbing on it, and no deodorant or antiperspirant on skin that is still pink. A fragrance-free product is usually fine from the next day once the skin has settled, and a strongly fragranced or alcohol-based one is left until the skin has fully settled. Sweat itself is not a problem, but the friction and heat of a hard workout are, which is why exercise is put off while the skin is warm.
In the period that follows, treated hairs push out and shed, which can look like regrowth; it is the hair leaving the follicle. Shaving is fine once the skin has settled, with a clean razor and no pressure. Waxing, plucking and epilating are avoided between visits because they remove the hair the next session needs. Small crusts sometimes form over the densest hair; they come away on their own and are not picked. A blister, spreading redness, or a patch that turns darker or lighter than the surrounding skin is reviewed rather than waited out.
The general sequence of recovery, scab care and sun advice is on the laser hair removal aftercare page. Questions after treatment come back through WhatsApp during clinic hours and are answered in English and Chinese.
Your next step
1. MessageWhatsApp +65 8023 7170 with what is bothering you. A reply comes from the clinic, not a bot.
2. AssessmentDr Sin Yong examines you himself on Orchard Road, with ultrasound where earlier filler is involved.
3. A plan in writingWhat he would do, what he would not, the fee factors, and the option of no treatment.
Every treatment is performed by Dr Sin Yong personally. Singapore Medical Council registered · invited to share his clinical expertise internationally for CLASSYS, DEKA, Fotona, Hironic and Ilooda.
Book an assessment with Dr Sin Yong on Orchard Road; say if the underarm is also dark or irritated, so both can be looked at. How consultations work.
No. It removes the grey shadow of hair stubs under the skin, which some people read as lightening, but pigment in the skin is a separate problem with its own causes: friction, shaving and deodorant irritation, and in some people a metabolic one. Underarm darkening is assessed on its own, and the options are on the dark underarms treatment page. Reducing shaving does help stop the irritation that keeps feeding the pigment.
Not on the day. Deodorant and antiperspirant are washed off before treatment, and fragranced or alcohol-based products sting on freshly lasered skin and can irritate it. A fragrance-free product is usually fine from the next day once the redness and bumps have settled. Keep the fold cool and dry for the rest of the day, avoid tight sleeves rubbing on it, and put off heavy exercise while the skin is still warm.
It can be, when the wavelength matches the skin of the fold. Underarm skin is often darker than the arm beside it, so the choice usually moves toward 1064 nm Nd:YAG, which is less absorbed by surface melanin and reaches the follicle with a wider safety margin, with epidermal cooling and a test patch where the fold is markedly darker. A recent tan, sunburn or self-tan is a reason to wait.
It helps by reducing the cause. Ingrown hairs come from shaving coarse hair at an angle so that the sharp tip curls back into the skin. Fewer, finer regrowing hairs mean less shaving and fewer sharp tips, which is the mechanism. Laser does not treat an existing inflamed or infected bump, which is settled first, and where bumps persist the cause is examined, since folliculitis can look similar.
Yes, shave; do not wax, pluck or epilate. The laser needs the hair shaft and its pigment in the follicle, and waxing removes both. Shaving a day or two before is ideal, because a freshly shaved fold is often nicked and raw, and inflamed skin absorbs more energy and marks more readily. Between visits, shaving is fine once the skin has settled, with a clean razor and no pressure.
Long-pulsed Nd:YAG laser-assisted hair removal in pigmented skin: a clinical and histological evaluation. Archives of Dermatology 137(7), 2001. source
Laser hair removal: a review. Dermatologic Surgery 39(6), 2013. source
A review of the adverse effects of laser hair removal. Lasers in Medical Science 21(3), 2006. source
About this page: written and medically reviewed by Dr Sin Yong, MBBS (NUS), MRCS (Edinburgh) · Last reviewed 20 October 2026 · Illustrative images only, not patients · Editorial policy
