What are melanocytes?
Melanocytes are dendritic (branch-shaped) cells located in the basal layer — the deepest layer of the epidermis. Each melanocyte connects to roughly 30–40 neighbouring skin cells, distributing the melanin it produces throughout the surrounding skin via small packages called melanosomes. This is how an even skin tone is normally maintained.
Every person has a broadly similar number of melanocytes, regardless of skin tone. What differs between individuals — and what determines natural skin colour — is how active those melanocytes are, how much melanin each one produces, and how that melanin is packaged and distributed.
What makes melanocytes overactive?
Melanocytes respond to several triggers: UV radiation is the strongest and most common; hormonal shifts such as pregnancy, the contraceptive pill, or HRT can stimulate melanocytes broadly across the face, producing melasma; inflammation from acne, injury, or aggressive skincare stimulates melanocytes locally at the site of the trauma, producing post-inflammatory hyperpigmentation; and genetics determines baseline melanocyte reactivity, which is why Fitzpatrick Type IV–VI skin tends to respond more dramatically to the same triggers than fairer skin.
When melanocytes are overstimulated in a specific area, they produce and deposit melanin faster than the surrounding skin, creating a visibly darker patch. Pigmentation treatment works by calming this overactivity and — critically — reducing future triggers, particularly UV exposure.