Hormonal changes related to pregnancy or such changes caused by starting or stopping birth control pills can also cause acne.

Another factor is heredity or genetics; there is evidence to support the fact that the tendency to develop acne can be inherited from parents.

Apart from this certain drugs, including androgens and lithium, are also known to cause acne.

Greasy cosmetics may cause further plugging of the follicles in the skin and hence can precipitate the onset of acne