Chewing areca nut is a cause of oral submucous fibrosis, a premalignant lesion which frequently progresses to mouth cancer. According to Medline Plus, "Long-term use betel-areca preparations has been associated with oral submucosal fibrosis (OSF), pre-cancerous oral lesions and squamous cell carcinoma. Acute effects of betel chewing include asthma exacerbation, hypertension, and tachycardia. There may additionally be a higher risk of cancers of the liver, mouth, esophagus, stomach, prostate, cervix, and lung with regular betel use. Other effects can include altered blood sugar levels, which may in turn increase the risk of developing type 2 diabetes."