Certain steps and factors are necessary in the development of a pimple.

It all starts with a genetic predisposition and the ability to convert testosterone to dihydrotestosterone in the sebaceous gland due to the presence of the enzyme 5 alpha-reductase.

Sebaceous glands enlarge, produce more oil, the skin start shedding more skin cells and clog the pores, and when bacteria enter the scene, things really get going. Now its only a matter of breakage of the follicles and inflammation and you have full-blown acne.

The four factors involved in the development of a pimple, are:

 
• increased production of oil stimulated by androgenic (male) hormones.  
• obstruction of the opening of the follicle caused by increased production of scales.  
• infection by a bacterium, namely Propionibacterium acnes.  
• rupture (breakage) of the follicle, leading to inflammation.

Genetic factors may play a role. Acne often occurs in families.

Stress may aggravate acne but is not causal. Acne may cause stress.

The earliest lesions of acne are closed comedones (clogged pores not open to the surface, whiteheads) and open comedones (clogged pores open to the surface, blackheads). Breakage of these structures leads to the development of all other lesions.