Tobacco (cigarettes, pipes, cigars, chewing tobacco, and snuff) is the most common cause of oral cancer. Combining tobacco use with heavy drinking can also foster the development of oral cancer. Bad hygiene, prolonged irritation of the oral cavity, and extended exposure to strong sunlight on the lips are among other causes of the disease. Many dentists believe vitamins A and E can help prevent the acquisition of oral cancer. Early symptoms of oral cancer include: a sore on the lip, in the mouth, or in the throat that does not heal; a lump on the lip, in the mouth, or in the throat; a red or white patch found anywhere in the mouth; unusual pain or bleeding in the mouth; swelling of the mouth; and any difficulty or discomfort felt in chewing or swallowing.