Acne develops when hair follicles become clogged. This condition can occur almost anywhere on the body -- including the chin and neck. Factors that contribute to acne in these areas include makeup, sweat, dirt and cell phone use.
The chin and neck areas are common places to apply makeup, which is why you may suffer from breakouts along the jawline. It perpetuates a cycle of acne when you use pore-clogging makeup to cover up existing blemishes. Consider using makeup that contains salicylic acid to help treat acne while covering outbreaks. Your neck acne could be the result of using a brush to apply powder or blend makeup, so be sure to clean your brushes periodically to remove dirt and oil.
If you spend a lot of time working out out or exerting yourself to the point of sweating, your chin and neck are likely places to suffer from acne. If you sweat across the back of your neck or experience friction in that area, you're likely to have clogged pores and subsequent breakouts. Wearing breathable clothing while working out, and showering promptly afterward, will help you stop acne from forming across the neck and chin.
Think about how often you rest your chin in your hand, rub the back of your neck or otherwise touch your face each day. Each time you put your hands on those acne-prone areas, you are transferring the dirt, oil and bacteria from your hands to the chin and neck, making them more susceptible to acne. Wash your hands frequently, and keep them away from your chin and neck.
Acne on the chin and neck is a growing problem among cell phone users. If you use your phone constantly, there's a good chance that you sometimes place the phone between your neck and chin to hold it in place while using both your hands on another task. The oil and dirt on your phone then becomes pressed into your skin and pores, resulting in breakouts along the jawline. Consider using a hands-free ear piece, and sanitizing your phone. Rubbing alcohol is safest for electronics because it evaporates fast; a weekly cleaning should stop this source of acne.