Freckles are small brown spots on the skin that are typically harmless and are caused by an overproduction of melanin, the pigment that gives skin its color. Freckles usually develop due to exposure to ultraviolet (UV) radiation from the sun. However, there are other factors that can cause freckles to appear without sun exposure, including genetics and a rare disease called xeroderma pigmentosum, which causes increased sensitivity to ultraviolet light.

It is important to note that sudden appearance of freckles may also be a sign of a skin condition called melasma, which is a hyper-pigmentation skin disorder that results in brown patches on the face, often on the cheeks, bridge of the nose, forehead, chin and above the upper lip. Melasma is believed to be linked to some combination of hormones and exposure to sun, heat or light.

In general, freckles are not a health threat and do not require treatment. However, if you notice any changes in the appearance of your freckles, such as irregular borders, changes in color or size, or if they start to itch or bleed, it is important to see a doctor or dermatologist. To prevent freckles, it is recommended to avoid excessive sun exposure and to use sunscreen with a high SPF.