Several types of lasers are used for hair removal, but the four main categories are alexandrite, diode, Nd:YAG, and ruby lasers. The right choice depends largely on your skin tone and hair color, because each laser operates at a different wavelength that interacts with melanin differently. Most modern clinics rely on alexandrite and diode lasers as their workhorses, with Nd:YAG reserved for darker skin tones and ruby lasers mostly phased out of routine practice.
How Lasers Remove Hair
All hair removal lasers work on the same core principle: selective photothermolysis. The laser emits a beam of light at a specific wavelength, and melanin (the pigment in your hair shaft and follicle) absorbs that energy. Because the hair shaft and the cells at the root of the follicle contain far more melanin than the surrounding skin, the laser energy concentrates there. That energy converts to heat, which destroys both the hair root and the stem cells responsible for regrowth.
Wavelengths between 600 and 1,200 nanometers (nm) are the sweet spot for reaching melanin deep in the follicle while passing through the outer layers of skin with minimal damage. Shorter wavelengths within that range are absorbed more strongly by melanin, making them powerful but also riskier for darker skin. Longer wavelengths penetrate deeper and are gentler on pigmented skin, though they may need more energy to get the job done. This tradeoff is why different laser types exist.
Alexandrite Laser (755 nm)
The alexandrite laser operates at 755 nm and is widely considered the gold standard for hair removal on lighter skin tones, specifically Fitzpatrick skin types I through III (fair to light-medium complexions). Its wavelength sits in a range where melanin absorption is very high, which means it’s exceptionally efficient at heating and destroying follicles in fewer pulses. It also covers large treatment areas quickly, making it a popular choice for legs, backs, and other broad surfaces.
The downside is that same strong melanin absorption. On darker skin, the epidermis contains enough melanin to compete with the hair follicle for laser energy, raising the risk of burns, blistering, or pigment changes. If you have medium-brown to dark skin, an alexandrite laser used alone is generally not the safest option.
Diode Laser (800 to 810 nm)
Diode lasers typically emit light at around 810 nm, placing them slightly deeper into the infrared spectrum than the alexandrite. This longer wavelength penetrates a bit further into the skin and absorbs slightly less superficial melanin, which gives the diode laser a wider range of compatible skin tones. It works well on light to medium-dark skin and is one of the most common lasers you’ll encounter at clinics.
Modern diode platforms have pushed this versatility even further. High-power triple-wavelength diode systems combine 755, 810, and 1,064 nm into a single pulse, essentially bundling the strengths of three laser types into one device. A clinical study of one such system found excellent hair reduction in 95.5% of treated areas across skin types IV and V (medium-brown to dark skin), with a strong safety profile. These combination devices are becoming increasingly popular because they let practitioners treat a broader range of patients without switching machines.
Nd:YAG Laser (1,064 nm)
The Nd:YAG laser emits at 1,064 nm, the longest wavelength used in hair removal. At this wavelength, the laser penetrates deeply into the dermis while the epidermis absorbs relatively little energy. That makes it the safest standalone laser for Fitzpatrick skin types IV through VI, which includes medium-brown, dark-brown, and very dark skin tones.
Clinical research using long-pulsed Nd:YAG treatments on darkly pigmented skin has confirmed selective follicular injury without epidermal disruption, meaning the laser damages the hair follicle while leaving the outer skin intact. The tradeoff is that the 1,064 nm wavelength is less efficiently absorbed by melanin overall, so treatments can require higher energy settings and may be slightly less comfortable. Hair reduction rates are generally a bit lower per session compared to alexandrite or diode lasers on ideal candidates, but for darker skin tones, the safety advantage is significant.
Ruby Laser (694 nm)
The ruby laser was one of the first lasers used for hair removal, operating at 694 nm. Its short wavelength is absorbed very aggressively by melanin, which made it effective for people with very fair skin and dark hair. However, that same characteristic made it prone to causing burns and pigment changes, especially on anyone with a tan or naturally darker complexion. Early studies noted superficial burning and both lightening and darkening of the skin as common side effects. Today, ruby lasers have been largely replaced by alexandrite and diode systems, which offer better speed, larger spot sizes, and improved safety profiles. You’re unlikely to encounter a ruby laser at a modern clinic.
IPL: Not Actually a Laser
Intense pulsed light (IPL) devices are often grouped with lasers in marketing materials, but they work differently. A laser produces a single, focused wavelength of light. IPL emits a broad spectrum of wavelengths in a diffused beam, which means the energy is spread across more targets and less precisely concentrated on the hair follicle. IPL can reduce hair growth, and it’s the technology behind most at-home devices, but it’s generally less powerful and less precise than true laser systems. For significant, long-lasting reduction, clinical-grade lasers tend to outperform IPL.
Which Laser Matches Your Skin Tone
The Fitzpatrick scale, a six-point classification of skin pigmentation, is the standard tool practitioners use to choose a laser type. The guiding principle is straightforward: the darker your skin, the longer the wavelength you need to avoid epidermal injury.
- Fitzpatrick I to III (fair to light-medium skin): Alexandrite, diode, or triple-wavelength diode lasers are all strong options. Alexandrite tends to be the fastest and most efficient in this range.
- Fitzpatrick IV to V (medium-brown to dark skin): Diode lasers (especially triple-wavelength systems) and Nd:YAG lasers are the safer choices. Alexandrite used alone carries higher risk of pigment changes.
- Fitzpatrick VI (very dark skin): The long-pulsed Nd:YAG at 1,064 nm is the recommended laser. Practitioners also use lower energy settings and longer pulse durations to protect the epidermis.
Hair color matters too. All of these lasers target melanin, so they work best on dark hair. Light blonde, red, gray, and white hairs contain little melanin and respond poorly to any laser type.
What to Expect During Treatment
Laser hair removal isn’t a one-and-done procedure. Hair grows in cycles, and the laser can only destroy follicles that are actively producing a hair at the time of treatment. At any given moment, only a portion of your follicles are in this active growth phase. That’s why treatments are spaced out over multiple sessions: typically 4 to 6 weeks apart for facial hair and 6 to 8 weeks apart for body hair, aligning with the different growth cycles in each area.
Most people need six to eight sessions for meaningful long-term reduction, though the exact number varies by body area, hair density, and the laser being used. Common side effects across all laser types include mild redness, slight swelling around the follicles, and temporary skin irritation. Pigment changes (either darkening or lightening of the skin) can occur, particularly in darker skin tones or when an inappropriate laser type is used. These changes are usually temporary but underscore why matching the laser to your skin type matters.