Hair Removal

LASER HAIR REMOVAL

by Dr W J Clayton Fellow of the American Society of Laser Medicine and Surgery
Associate Specialist in Dermatology, Royal Free Hospital, London NW3 2QG www.skinlaserclinic.co.uk

	Who is suitable
	Which laser?
	Is it permanent?
	How does it compare?
	Is it safe?
	The hair growth cycle
	How does it work?
	Unwanted effects
	What preparation is required?
	What after care is needed?

WHO IS SUITABLE ?
The best results are obtained when there is a large difference between the colour of the hair and the colour of the skin, i.e. black hair on fair skin. In these people the laser can be turned up very bright with little risk of harming the skin. Brown hairs do less well, ginger hairs respond poorly and blonde or white hairs hardly at all. Mediterranean, Middle and Far Eastern skin types can be treated with care. Darker skin types than these are not suitable for the stronger lasers because the skin pigment absorbs too much laser energy causing unwanted damage. Men and women can both be treated, and all parts of the body can be treated.

WHICH LASER ?
Q-switched Nd:YAG laser produces infra red light, it is not well absorbed by hair and skin pigment and is therefore not as effective as the other lasers, but it is safer on darker skins.
Long pulsed Ruby and Alexandrite lasers. Most of the rather limited independent scientific evaluation of laser hair removal has been done on the Ruby laser. The Alexandrite is very similar but with a slightly longer (deeper red) wavelength.
Diode laser produces a deep red light half way between the bright red of the Ruby and the infra-red of the Nd:YAG. High powers are used which can be painful.
Intense Pulsed light sources are not lasers but use a very bright flash bulb and a range of filters to deliver light to the skin. There are more variables to adjust than with a laser and its effectiveness is therefore more dependant on the experience of the operator.

IS IT PERMANENT ?
Laser hair removal is new and the longest observation period reported in the scientific literature is two years. Four out of the seven patients followed up still had stable hair loss. To the general public permanent means forever. In the laser community permanent means for longer than the normal hair cycle on that part of the body. Radiotherapy can induce hair loss for longer than the hair growth cycle, yet the hair can recover. Hair follicles are not completely destroyed by laser treatment, and they have great regenerative powers. It is therefore difficult to claim that laser hair removal is permanent; indeed most people will experience some regrowth within a year. To give you a more reasonable idea of what to expect a recent study published in the British Journal of Dermatology found that "three months after 4 treatments 95% of patients rated their response as considerably or moderately improved." They also found that "this degree of patient satisfaction is reflected in the high proportion who requested continued treatment at other sites after the treatment phase of the study was completed." A reduction in hair numbers and size for three months or more would be typical; but individual responses cannot be guaranteed.

HOW DOES IT COMPARE?
Waxing, plucking and bleaching do not damage the hair follicle so regrowth is quick. Skilled electrolysis does damage the hair follicle and is therefore permanent if done well, however eventually scarring and pigmentary changes can occur: unskilled electrolysis, including home based tweezer electrolysis, achieves little more than plucking. Electrolysis is slow, one follicle at a time and although each session is inexpensive, compared with laser therapy, only small areas can be treated. A laser flash is typically one centimetre across and can repeated every second, thus many hundreds of follicles can be treated at each visit. People with dark hair and fair skin generally feel that laser is the most effective method they have tried. Laser hair removal causes some discomfort, but most people find it more tolerable than waxing or electrolysis. In very sensitive areas an anaesthetic cream or skin cooling is usually sufficient.

IS IT SAFE ?
These lasers all produce a bright pure red light that is not cancer forming. It does not penetrate far into the skin, just a few millimeters. It is not like X-rays or radiotherapy. However it is dangerous to eyesight and protective goggles must be worn.

THE HAIR GROWTH CYCLE
Several treatments are required at the start of laser therapy because of the natural growth cycle of hair follicles. Each hair follicle goes through growing and resting phases, and the hair follicle is most vulnerable to laser treatment early in the growing phase. The number of active follicles and the length of the growth phase varies. The first treatment will only damage some of the follicles. After a few weeks previously resting follicles break into growth, these can then be lasered and the treatment repeated at approximately monthly intervals. In this way, after 3 - 6 treatments, most of the hair follicles in any particular site can be suppressed. Thereafter periodic top ups are all that is required.

HOW DOES IT WORK?
A laser is simply a source of very bright light that is all of one colour. The light is fired as a very brief flash and the energy is absorbed by dark hair follicles yet diffuses safely away in pale skin. The light energy is turned into heat as it is absorbed and the length of the flash is carefully controlled so that this heat does not spread and damage other parts of the skin. In this way the dark hair follicles can be selectively heated and damaged. This is sufficient to cause the hair to fall after a week or two and any subsequent regrowth to be finer and sparser.

UNWANTED EFFECTS
Laser light is extremely bright and protective goggles must be worn. Skin pigment may be darkened by this bright light, a sort of artificial tanning, but it occurs in the pattern of the laser spots and looks unsightly. If it occurs at all it will gradually fade but may take many months to do so. If the skin pigment absorbs too much laser energy the pigment can be damaged leaving pale patches, again these usually slowly recover. The same process can cause the skin to overheat resulting in blistering and possibly scarring. These unwanted effects are unlikely on pale skins. Individuals vary in their sensitivity to laser light so a test patch is essential. Recent tans are particularly vulnerable. You are advised to be as pale as possible before considering laser hair removal.

WHAT PREPARATION IS REQUIRED ?
There must be a dark hair in the follicle, so waxing and plucking should be stopped well before the treatment. You can trim snip or shave. On the day of treatment you should not apply deodorants, perfumes, talc or moisturisers containing sunscreen.

WHAT AFTER CARE IS NEEDED ?
Little special after care is required as the effects on the skin should be minimal. Often there is little to see. Some swelling and redness around the hair follicles, like goose bumps may occur but should be gone by the next day. If you have any concerns, especially if any blistering occurs, you should contact the laser clinic.

Dr W J Clayton
Associate Specialist, Dept Dermatology, Royal Free Hospital, London NW3 2QG
www.skinlaserclinic.co.uk