The hazards of betel nut with tobacco are harmful to teeth, digestive system and may cause cancer. 1. Harm to teeth: regular chewing of betel nut will wear down the teeth, make them red and black, and even cause them to fall out; smoking will also cause teeth to turn yellow and black, and betel nut with cigarettes will cause double damage to the teeth. 2. Harm to the digestive system: regular chewing of betel nut will cause damage to the taste nerves, salivary secretion, and betel nut will also stimulate the stomach lining, and even inflammation of the gastric mucosa. Smoking will promote the secretion of gastric acid and induce ulcers. 3. Carcinogenic: Frequent betel nut chewing may appear gum degeneration, mouth ulcers, and even lead to oral cancer. Smoking is also one of the carcinogenic factors. Note: Betel nut with tobacco is very harmful, so it is recommended to avoid eating betel nut and actively quit smoking.