Main reasons for the occurrence of freckles
Sunlight (UV Rays): Ultraviolet rays overstimulate the melanocytes (color-giving cells) in the skin. This causes the overproduction of a pigment called melanin, resulting in the formation of dark spots.
Hormonal changes: Freckles are more common in women. Changes in the hormones estrogen and progesterone during pregnancy, menopause, or the use of birth control pills increase melanin.
Genetic factors: If your mother or someone else in your family has freckles, you are more likely to get it.
Cosmetics: Some creams, makeup, and hair dyes that contain chemicals can make the skin more sensitive to sunlight and cause freckles.
Medications: Some medications can make the skin more sensitive to light (photosensitivity).
Thyroid problems: Some thyroid disorders can also cause skin discoloration.