Principles of Treatment
- General principle: the laser emits light preferentially absorbed by hair melanin. The energy converts to heat at the level of the hair follicle, progressively weakening its ability to regrow.
- Laser types: several wavelengths exist (e.g. alexandrite, diode, Nd:YAG). The choice of system depends on skin phototype, hair colour, and the area to be treated.
- Patient adaptation: the practitioner determines the protocol (energy, pulse duration, number of sessions) based on morphology, hair growth cycle, and skin history. Efficacy is reduced on white, grey, very fair, or red hair, which contain little melanin.
Session Process
- Prior consultation: a medical assessment is required to gather the patient's history, examine skin and hair, check for contraindications (medications, pregnancy, tanning, etc.), and explain the treatment plan. A test on a small area may be performed.
- Before the session: shaving the area 24–48 hours before is generally required; waxing, epilating, or plucking must be avoided for several weeks; and recent sun exposure should be limited. Photosensitising products and certain medications will be noted and possibly suspended.
- Process: the patient wears eye protection. The practitioner calibrates the device and performs successive passes over the area. A cooling system or topical anaesthetic cream may be used to improve comfort. Duration varies by area (a few minutes for underarms, up to one hour for large body areas).
- Comfort and sensations: tingling, warmth, or a stinging sensation are common but transient. The experience depends on individual sensitivity and the parameters chosen.
Post-session Course and Results
- Immediate post-treatment effects: redness, slight perifollicular swelling, and a warm sensation are common and resolve within a few hours to a few days. Minor crusting or mild flaking may occur.
- Onset of results: treated hairs fall out progressively over 1 to 4 weeks. Multiple sessions are needed to target hairs in the growth phase: an average of 6 to 8 sessions, spaced depending on the area (4–8 weeks for the face, 6–10 weeks for the body). These figures are indicative and variable.
- Duration and variability: laser hair removal generally leads to a lasting reduction in hair growth, but results vary depending on age, hormones, phototype, and the area treated. Occasional maintenance sessions may be necessary.
Contraindications and Precautions
- Common contraindications: pregnancy and breastfeeding, active skin lesions (infection, wounds), recent tanning or sunburn, use of uninterrupted photosensitising medications, marked history of keloid scarring (to be discussed), recent treatment with isotretinoin (wait for the physician-recommended interval).
- Precautions: inform the practitioner of any dermatological history, medications (anticoagulants, photosensitisers), or tattoos in the treatment area. For darker skin (phototypes IV–VI), the protocol requires particular care to limit pigmentation risks; the choice of wavelength and parameters is crucial.
- Special areas: genital and periareolar areas require a specific evaluation and informed consent.
Risks and Possible Side Effects
- Expected and transient effects: redness, swelling, folliculitis, flaking.
- Rarer adverse effects: localised hyperpigmentation or hypopigmentation, superficial burn, crusting, scar (rare if precautions are observed), persistent pain, allergic reaction to contact materials.
- Paradoxical effect: paradoxical hypertrichosis (localised increase in hair growth) can occur exceptionally, particularly at the periphery of the treated area.
- Monitoring: these risks are explained and managed during the consultation. Medical follow-up allows early detection and treatment of complications if they arise.


