Laser Hair Removal: How It Works and How Many Sessions

How does laser work on hair?

The melanin pigment in the hair absorbs the laser energy, which turns into heat that damages the follicle and weakens its ability to grow new hair. That is why laser works best on dark, coarse hair and less well on blonde, white or red hair, which contain little pigment.

Hair grows in cycles, and laser mainly affects hairs in the active growth phase. Because not all hairs are in that phase at the same time, several spaced-out sessions are needed.

How many sessions do I need, and how far apart?

Most people need around 6 to 8 sessions, some need more, followed by occasional top-ups when needed. The interval between sessions depends on the area; these are common approximate ranges:

Hair growth driven by hormonal conditions such as polycystic ovary syndrome may need more sessions, together with medical follow-up of the underlying cause.

• Face: about every 4 to 6 weeks.
• Underarms and bikini area: about every 4 to 8 weeks.
• Legs and back: about every 6 to 12 weeks.
• Your doctor will set the schedule that suits how your hair responds.

What types of laser are there, and will one suit my skin?

Your doctor chooses the device and its settings according to your skin and hair colour. Alexandrite lasers generally suit fair to olive skin, diode lasers are used across a wide range of skin tones, and Nd:YAG lasers have a longer wavelength and are considered a safer choice for brown and dark skin.

Intense pulsed light (IPL) devices are not true lasers and may be less suitable for darker skin. What matters more than the device name is choosing the right settings and assessing your skin first, which lowers the risk of burns and changes in skin colour.

How should I prepare for a laser session?

Good preparation makes the session safer and more effective. Follow these steps, and always follow your doctor's instructions:

• Shave the area about a day before, and avoid waxing, plucking or threading for 4 to 6 weeks before treatment, because the laser needs the follicle in place.
• Avoid direct sun exposure and tanning for about two weeks before the session.
• Stop strong exfoliating creams and topical retinoids on the area a few days before, as your doctor advises.
• Arrive with clean skin, free of deodorant, creams or make-up on the area.
• Tell your doctor about all medicines and supplements you take, and any history of cold sores (herpes) or light sensitivity.

What aftercare is needed, and what are the side effects?

Mild redness and small bumps around the follicles are normal for a few hours to a day or two. After about 1 to 3 weeks the treated hairs start to shed, which can look like regrowth when they are actually being pushed out of the skin.

Less common effects include blisters, burns and lightening or darkening of the skin, which are more likely with tanned skin or unsuitable settings; rarely, hair growth can increase in nearby areas. To reduce these risks:

• Apply cool compresses and a gentle moisturiser your doctor recommends.
• Avoid very hot water, saunas and intense exercise for a day or two.
• Use a broad-spectrum sunscreen of SPF 30 or higher every day and avoid direct sun, especially in our hot summers.
• Do not scratch or exfoliate the area, and do not pluck between sessions; shaving is fine.

Who should postpone laser sessions?

Laser suits many people, but some situations call for postponing treatment or a specific assessment by your doctor first:

• Pregnancy; treatment is usually postponed until after the birth because of limited safety data.
• A recent suntan or self-tan.
• Taking medicines that make the skin sensitive to light, or recent use of isotretinoin for acne; your doctor will decide when it is suitable to start.
• An infection, wound or active inflammation in the area.
• Changing moles or undiagnosed skin spots in the area, which need to be examined first.