Smokeless tobacco products consist of tobacco or a blend that’s chewed or sucked rather than smoked.  Using chewing tobacco can cause serious health problems including gum irritation, an increased risk of heart attack, and oral cancer.  This can also cause tooth decay due to the high amounts of sugar it contains.  Coarse particles can irritate your gums and scratch away at the enamel, making your teeth more vulnerable to cavities.  The area where that chewing tobacco is kept can develop gum disease (gingivitis) and possibly tooth loss.
People who use smokeless tobacco are more likely to develop small white patches called leukoplakia inside their mouths where the chew is placed.  These lesions are precancerous and, after usage stops, the lesions usually go away in a few months.  Those lesion that become cancerous may require surgery to remove and can leave your jaw, chin, neck or face disfigured.