It can be caused due to excessive exposure to sunlight, excessive or uneven usage of birth control pills, homone replacement therapy and also during pregnancy
Genetic predisposition is also a major factor.
Avoid exposure to sunlight.Apply spf cream(spf 9 or higher) one hour before goining in sun,wear hat etc.Thats why u are getting them on sun exposed part of body -face.
the affected areas with aloe vera
Rub an oatmeal-and-milk mixture to the affected areas every day. Oatmeal is a natural skin-exfoliating substance
Apply turmeric paste and besan to the affected areas every day.
Besides you need Sarivadayasavam 2 tsf thrice daily after meals(ayurvedic).
It will take 6-9 months to cure.
Food to avoid : Tamarind, spicy and fried food, garlic, brinjal, green chillies, eggs, fish, chicken.