Although there have been no definite conclusions as to the cause of acne, most doctors agree that acne can be caused be a variety of factors that include increased hormone levels at puberty, diet, weather, and even genetics.
One of the biggest causes of acne is the increased amount of androgens in the body at puberty. Androgens are hormones that are released at puberty. These androgens cause the sebaceous glands to enlarge and get overstimulated, causing acne.
In both men and women, this increased stimulation and enlargement of the sebaceous glands causes them to produce seblum, i.e., oil. This oil, when it mixes with the dead skin cells and bacteria present on the skin blocks the pores in the skin. The bacteria in the skin multiplies inside these pores, causing swelling which eventually leads to pimples and acne.
The occurrence of acne varies from person to person. Researchers now believe that the spread and extent of acne is largely determined by hereditary. If you have parents who had extensive acne, chances are, you will suffer from it too.
Stress has also been directly related to acne. Although stress by itself cannot cause acne, it influences and aggravates the conditions that lead to acne. When someone is stressed, the body produces more hormones like cortisol, which eventually leads to acne through the process mentioned above.
Your diet has a major role to play in causing acne. Greasy, fried, oily foods have been known to cause acne as eating a diet rich in such foods causes the skin to produce excess oil. Dirty skin has been known to be another cause of acne as it blocks the skin pores and encourages the spread of bacteria.