How does laser reduce hair?
Laser light is absorbed by the melanin in the hair, converts to heat and heats the follicle enough to damage it. It acts mainly on hairs in the growth phase.
Hairs do not all grow at the same time; at any moment just some of the hairs in an area are in the growth phase where laser is effective. This is why sessions are repeated at intervals, catching a different group of hairs each time. Shedding of treated hairs is usually noticed over days to a few weeks.
The aim is usually to reduce the number and thickness of hairs rather than remove every one. Some follicles weaken and produce finer, lighter hair, while others may reactivate over time.
How many sessions are needed and how are intervals set?
Most people need between six and ten sessions or more. Intervals are shorter for faster-growing areas such as the face and neck, and longer for areas such as the back and legs.
The number depends on hair thickness and colour, the area, hormonal status and skin tone. A maintenance session after the main course is common, especially when hormonal factors are involved.
Between sessions tweezing, waxing and epilators are avoided because they pull the hair out from the root and remove the target the laser needs. Shaving is used instead, so the target stays in the follicle.
How do skin type and hair colour change the result?
Dark hair on lighter skin is the easiest combination to treat. On darker skin, competition for the light from skin melanin means longer wavelengths and more careful settings. White and grey hair usually do not respond enough.
Hair and skin melanin absorb the same light. The darker the hair is relative to the skin, the more selectively the light works. As the skin gets darker the risk of burns and colour change rises, so the device type and energy are adjusted, and more sessions may be needed.
In light blond, red, grey and white hair there is little melanin to target, so the response may be weaker than expected and other methods may be discussed. See the page on laser for different skin tones for more detail.
How should I prepare?
Avoid tanning and root-removing hair removal for at least four to six weeks beforehand, and arrive with the area shaved and clean. Medicines you take should be reported at consultation.
Some photosensitising medicines, isotretinoin use, and an active infection or wound in the area can delay treatment. Cosmetic laser hair removal is usually postponed during pregnancy.
Tell the practitioner about any recent peel, sunburn or tan on the area. A small test patch with a few days of observation is a sensible way to check how your skin responds.
What are the possible side effects and risks?
Redness, swelling around the follicles and temporary warmth are common. Less often, burns, blistering, temporary or lasting colour change, infection and, rarely, increased hair growth have been reported.
Risk relates to skin tone, sun exposure, device settings and aftercare. Adequate cooling improves comfort and protects the skin; cooled systems are covered on the cooling laser hair removal page.
If there is severe pain, blistering, widespread redness or a wound, speak to the treating doctor rather than applying ointments or medicines on your own.
Frequently asked questions
How long do the effects of laser hair removal last?
Laser can reduce hair count and thickness for a long time, but it cannot be said that every follicle is gone. If hormonal factors are present, hair can return and maintenance sessions may be needed.
Can laser hair removal be done in summer?
Treating tanned skin raises risk. It may be possible with strict sun protection, but the doctor sets the settings and timing individually. See the page on laser in summer.
Can I have laser hair removal during pregnancy?
Cosmetic laser hair removal is postponed during pregnancy and often during breastfeeding. The safest approach is to wait until after.
How should I remove hair between sessions?
Shaving is used because it does not pull out the root. Tweezers, wax, epilators and chemical pulling are not advised since they remove the target in the follicle.
Does laser work on white or grey hair?
With little melanin the response is usually limited. Other methods may be considered; the doctor explains the options at consultation.
Sources (5)
- American Academy of Dermatology: Laser hair removal: Overview
- American Academy of Dermatology: Laser hair removal: FAQs
- Journal of the European Academy of Dermatology and Venereology: Evidence-based review of hair removal using lasers and light sources (2006)
- Journal of Cosmetic and Laser Therapy: Efficacy of lasers and light sources in long-term hair reduction: a systematic review (2022)
- Dermatologic Surgery: Paradoxical hypertrichosis after laser therapy: a review (2010)
This content is for general information and does not replace a personal medical assessment.