Acne is caused due to overproduction of oil on the skin, irregular shedding of dead skin cells and bacteria. The sebaceous glands produce oil and blemishes are formed when the dead skin cells trap the oil within follicles. In addition bacteria, some medications and genetics could cause increased oil secretions. Some are more prone to acne on neck than others, with risk factors being age, menstruation, pregnancy, the use of certain medications, exposure to oily cosmetics, genetic predisposition and friction. In addition, people who wear helmets, tight collars or frequently carry packs with shoulder straps may develop acne on the neck because of the friction these items create against the skin.