Medical hair removal lasers: what's the difference? How to choose a device based on skin color and hair type

The differences in medical hair removal lasers stem mainly from the wavelength of light and suitability for different skin colors[1]Alexandrite is considered safer for fair to standard skin tones, diode for standard to moderately dark skin, and Nd:YAG for dark skin.[1][2]With any device, gray hair and blond hair are harder to treat, which remains the same.[3].

What differs by laser type?

All lasers work the same way: they cause hair's black pigment (melanin) to absorb light, convert it to heat, and damage the tissue that forms hair.[1][4]The difference lies in the wavelength of light—alexandrite at 755 nm, diode at 808–810 nm, and Nd:YAG at 1064 nm.[4].

The longer the wavelength, the deeper the light penetrates and the less it is absorbed by melanin on the skin surface.[3]For this reason, Nd:YAG with its longer wavelength is less likely to cause burns and other damage to skin, while IPL is more likely to cause them.[3].

The darker a person's skin tone, the more melanin in their skin absorbs light, making heat-related complications more likely.[1]With any device, cooling the skin while treating it helps protect the surface.[1].

Advantages and disadvantages by device?

Alexandrite is strongly recommended in the Japanese Association of Plastic Surgeons guidelines because it causes less pain by cooling the skin to protect the surface, and provides lasting results.[5]However, effectiveness varies with hair root depth, hair color, and skin color, and paradoxical hair growth (hypertrichosis) is also possible.[5].

Diode is a device developed for people with darker skin tones and allows relatively safe hair removal.[5]Nd:YAG is effective for hair removal regardless of skin type and is considered to have high safety even on dark skin.[5][2]On the other hand, some report that Nd:YAG tends to cause more pain and redness.[6].

IPL is different from lasers—it is light that combines multiple wavelengths. As a result, its power to target hair melanin is inferior to lasers, but it can be applied over a wide area at once and causes less pain.[5].

Ablative versus accumulative heating: which to choose if pain is a concern?

If you are concerned about pain, accumulative heating is also an option. The Japanese Association of Plastic Surgeons guidelines strongly recommend accumulative heating for those who want it, as it is effective for hair removal and causes less pain.[5].

However, research comparing ablative and accumulative heating in the same individuals is not included in this material. Rather than which works faster, it is more practical to choose based on your pain tolerance and skin condition.

Hair reduction and precautions based on research?

Hair reduction varies by laser type, number of sessions, and hair color, and research shows approximately 40–80% reduction.[3]In a study of 60 people treated sequentially with three laser types, hair reduced by 75.07% at six months with no long-term side effects.[4].

Even in a summary of research comparing devices for people with dark skin tones, it is not yet clear which is best.[7]Hyperpigmentation can also occur; in a study of alexandrite on the face, it was seen in 10% of subjects.[6].

Burns have been reported from light treatment performed by non-medical personnel.[2]Whether the facility can adjust settings based on skin color is also an important consideration when choosing.[2].

What should be examined at a consultation?

You should have the doctor examine your skin color and sun exposure level, hair thickness and color, and the area you want to depilate. These factors determine which device and settings are appropriate.

Then confirm the device to be used, pain management, and what will be done if hypertrichosis or hyperpigmentation occurs. Which device is right for you cannot be determined from an article alone, so have your skin and hair actually examined before deciding.