blackheads form when a clog or plug develops in the opening of hair follicles in your skin. each follicle contains one hair and a sebaceous gland that produces oil. this oil, called sebum, helps keep your skin soft. dead skin cells and oils collect in the opening to the skin follicle, producing a bump called a comedo. if the skin over the bump stays closed, the bump is called a whitehead. when the skin over the bump opens, exposure to the air causes it to look black and a blackhead forms.
some factors can increase your chances of developing acne and blackheads, including:
producing too much body oil
the buildup of the propionibacterium acnes bacteria on the skin
irritation of the hair follicles when dead skins cells don’t shed on a regular basis
undergoing hormonal changes that cause an increase in oil production during the teen years, during menstruation, or while taking birth control pills taking certain drugs, such as corticosteroids, lithium, or androgens
some people believe that what you eat or drink can affect acne. dairy products and foods that increase blood sugar levels, such as carbohydrates, may play a part in triggering acne, but researchers aren’t convinced that there’s a strong connection.