More recent research has suggested that hormonal fluctuation in the body may be the main cause of acne, such as during puberty, pregnancy, menstruation, and times of stress when the skin tends to be more oily. When dead skin cells and sebum (the natural oil produced by glands in the skin) clog pores, acne forms and can become quite severe if left untreated. Fortunately, there are various treatment methods, from facial cleansers with benzoyl peroxide or salicylic acid, to natural remedies like tea-tree oil and apple cider vinegar. Some of them are more effective than others and some will be effective for some people and not to others. It depends of what kind of acne you have.