There is not one single cause of acne. Why some people get acne and others do not is not known. However, many associated factors can influence the development of acne, such as hormonal influences, bacterial infection, heredity, climate and substances applied to the skin. Steroid hormones, birth control pills and androgenic hormones such as testosterone can cause or aggravate acne. Cosmetics and some topical creams or lotions can cause or aggravate acne, especially those that contain oils.
Stress can aggravate acne by increasing the secretion of adrenal hormones.
Acne tends to flare during the menstrual cycle due to hormonal fluctuations experienced prior and during ovulation. Overexposure to the sun can worsen acne. Oily sunscreen lotions are not recommended if your skin is acne prone. Acne can occur at any age. Adolescents are more likely to get acne because of the active secretion of hormones called androgens, produced by the adrenal and reproductive glands.