Laser hair reduction: how it works and how many sessions

Key takeaways

• Laser targets pigment in the hair root. Dark, coarse hair responds well. Grey, white, blond and red hair respond poorly.
• Each session catches only the hairs in their growing phase, so a series is needed.
• Most people need about four to eight sessions; facial hair often needs more and longer maintenance.
• The correct term is long-term hair reduction. Regrowth is usually finer and lighter, and maintenance sessions may be needed.
• Shaving is fine before treatment. Waxing, threading and plucking are not, because the laser needs the root in place.

How does laser hair reduction work?

People ask me, "Doctor, does the laser burn the hair?" Basically, yes, but the clever part is where.

See, what happens is, the laser sends a beam of light of a specific wavelength. The dark pigment, melanin, in the hair shaft and root absorbs that light and turns it into heat. The heat travels down the hair to the follicle and damages the parts that make new hair. The surrounding skin, which has less pigment than the hair, is meant to absorb less. Mayo Clinic describes this simply: the laser targets the pigment in the hair, and the heat damages the follicle and slows future growth.

The medical term for this principle is selective photothermolysis, which the Indian standard guidelines on laser and IPL hair reduction use as their basis.

That is very important to understand for Indian skin. Brown skin also has pigment, so the laser must be chosen and set so that the hair absorbs much more energy than the skin. I explain this in detail in is laser hair reduction safe for Indian skin?.

Why do I need so many sessions?

Hair does not all grow at the same time. At any moment, some follicles are actively growing, some are resting and some are shedding. The laser works best on hairs in the active growing phase, when the hair is attached to a pigmented root.

So each session catches one batch. The next session, weeks later, catches the next batch as it starts growing. That is why spacing matters and why one session is never enough.

How many sessions sources describe: - The American Academy of Dermatology says most patients need two to six treatments, usually every four to six weeks. - Mayo Clinic says most people need four to eight sessions, spaced several weeks apart. - An Indian study of 200 women with skin types IV and V treated for facial hair advised patients to expect six to eight sessions, followed by maintenance every six to eight months.

Facial hair in women is often hormone-driven, which is why it can need more sessions and ongoing maintenance. My article on facial hair and PCOS explains why.

Is laser hair reduction permanent?

Not in the strict sense. The Indian guidelines recommend using the term "long-term hair reduction" rather than "permanent hair removal". The American Academy of Dermatology notes that most patients remain hair-free for months or years, and that hair that does grow back tends to be finer, lighter and sparser. It also notes maintenance treatments may be needed.

So I tell my patients plainly: expect much less hair, and finer hair, not zero hair forever.

How do I prepare for a laser session?

These preparation points come from the Indian guidelines and Mayo Clinic: - Shave the area a day before, so a short stubble of about 1 to 5 mm remains. This lets the laser reach the root without burning surface hair. - Stop waxing, plucking, threading, bleaching and epilation once treatment begins. Mayo Clinic advises stopping waxing and plucking at least four weeks before. - Avoid tanning. Tanned skin absorbs more laser energy and is more prone to burns. Avoid beach days, sunbathing and self-tanning creams before sessions, and use sunscreen. - Tell your doctor about medicines that make you sensitive to light, such as isotretinoin or some antibiotics, and about any history of cold sores, keloids, vitiligo or psoriasis. - Come with clean skin, free of makeup, creams and deodorant on the area.

A numbing cream may be used if you are sensitive.

What does a session feel like, and what happens after?

Most people describe each pulse as a snap or a quick warm sting. A cooling device or cooling gel makes it more comfortable. Smaller areas like the upper lip take a few minutes; larger areas like legs take longer.

After treatment: - Mild redness and swelling around the hair follicles are common and usually settle within one to three days, according to the American Academy of Dermatology. A cool compress helps. - Treated hairs shed over days to weeks. Mayo Clinic notes this is expected. It can look like the hair is growing, but it is the treated hair being pushed out. - Avoid direct sun on the area, and use sunscreen. - Rare side effects include blistering, crusting, infection and changes in skin colour, which are usually temporary.

Who is not a good candidate?

The Indian guidelines list situations where laser is avoided or needs care: - Age under 15 - Active skin infection in the area - Light-sensitive skin conditions such as lupus - Photosensitising medicines, keloid tendency, vitiligo or psoriasis in the area, a history of cold sores, and unrealistic expectations

Laser also works poorly on grey, white, blond and red hair, because there is little pigment for the laser to target. Mayo Clinic notes this as well.

How we approach this at Dr Tvacha

Laser hair reduction is one of the treatments available at our centres in Thane, Andheri, Bandra and Dahisar. Before the first session, I check your skin type, hair colour and thickness, medicines and, for women with facial hair, whether hormones need looking at. The Rs 499 skin consultation is the starting point, and the plan, number of sessions and fees are written down before you pay. Read about the Second Layer Skin Plan or find a centre.

Written by

Dr Amit KarkhanisAesthetic Physician · MBBS, Dip. Dermatology (UK) · Reg. No. 2001/02/1124

Founder of Dr Tvacha, practising in Thane since 2005. Leads the weight loss and hair programmes.