Taking betel nut for a long time is harmful. Long-term consumption of betel nut will cause the following problems. 1. Oral submucosal fibrosis: chewing betel nut for a long time will seriously stimulate the oral mucosa, causing fibrosis of the mucosa in the oral cavity, which will seriously affect the chewing function and the opening function. 2. Oral ulcers: Frequent betel nut chewing will cause the oral salivary glands to be unable to secrete saliva normally, resulting in the formation of multiple cysts, causing ulcers in the oral cavity. 3. Oral cancer: Oral submucosal fibrous lesions are pre-cancerous lesions that can easily lead to oral cancer. Frequent betel nut chewing will cause whitening of oral mucosa, and eventually moss-like changes. Long-term appearance will induce oral cancer. Precautions: Betel nut as a carcinogen should be minimized to prevent cancer.