Phototherapie

Phototherapie, or phototherapy, is a medical treatment that uses light to treat a range of health conditions. It employs specific wavelengths of ultraviolet, visible, or sometimes infrared light delivered by lamps, LEDs or lasers. In some contexts, phototherapy also refers to bright light therapy used for mood and circadian rhythm disorders, or to neonatal blue-light therapy for jaundice.

In dermatology, ultraviolet phototherapy applies UVA, UVB or narrowband UVB light to the skin to influence immune responses and cell growth. Narrowband UVB is a common and relatively safe option for plaque psoriasis and atopic dermatitis, while UVA in combination with a photosensitizing drug (PUVA) is used for certain resistant or specialist conditions. Dosing is individualized and aims to balance efficacy with the risk of skin damage; treatments are typically given two to three times per week in clinical settings, with gradual dose increases.

Neonatal phototherapy uses blue light (around 420–470 nm) to convert excess bilirubin into water-soluble forms that can be excreted, helping to treat newborn jaundice. Blue-light therapy in other settings, such as acne or mood disorders, relies on similar principles of light-therapy but with different light spectra and treatment goals.

Photodynamic therapy is a related approach in which a photosensitizing agent is applied or ingested, and the target tissue is then exposed to a specific light wavelength to destroy abnormal cells. This modality is used for certain precancerous and cancerous skin lesions, as well as some other conditions.

Safety and monitoring are important in phototherapy. Potential risks include skin pigmentation changes, sunburn-like reactions, eye damage with insufficient protection, and, with prolonged UV exposure, an increased lifelong risk of skin cancer.