Causes of Hyperpigmentation

Hyperpigmentation refers to the darkening of areas of skin caused by increased production or abnormal distribution of melanin, the pigment responsible for skin, hair, and eye color. It can arise from a variety of physiological, environmental, and pathological factors.

Common triggers include chronic sun exposure, which stimulates melanocytes to produce excess melanin as a protective response; hormonal fluctuations—particularly elevated estrogen and progesterone levels during pregnancy or with oral contraceptive use—leading to melasma; and post-inflammatory changes following acne, eczema, psoriasis, or trauma, where inflammation activates melanocytes and results in residual pigmentation.

Other contributing causes encompass certain medications (e.g., antimalarials like hydroxychloroquine, chemotherapeutic agents, and tetracycline antibiotics), endocrine disorders such as Addison’s disease (characterized by adrenal insufficiency and elevated ACTH, which cross-reacts with melanocortin receptors), and rare genetic conditions like hemochromatosis or Laugier–Hunziker syndrome.

Diagnosis relies on clinical evaluation—including Wood’s lamp examination to assess pigment depth—and, when indicated, dermoscopy or biopsy to exclude melanoma or other pigmentary disorders. Management is tailored to etiology and may involve strict photoprotection, topical depigmenting agents (e.g., hydroquinone, retinoids, azelaic acid), chemical peels, laser therapy, or systemic treatment of underlying conditions.