Reversing the Youth Tobacco Epidemic Act of 2019 This bill revises requirements related to the safety, sale, and advertisement of tobacco products, including electronic nicotine delivery systems (e.g., e-cigarettes, e-hookah, e-cigars, and vape pens). Among other requirements, the bill requires the Food and Drug Administration (FDA) to implement regulations to require color graphics on the labeling of cigarette packages, depicting the negative health consequences of smoking; requires the FDA to apply regulations on tobacco products to all tobacco products, including e-cigarettes; prohibits the retail online sale of tobacco products, including electronic nicotine delivery systems; prohibits flavors other than tobacco in a tobacco product; prohibits the use of flavored products in an electronic nicotine delivery system, except in specified circumstances; increases the user fees that the FDA collects from manufacturers and importers; directs the FDA to regulate products containing synthetic nicotine (not made or derived from tobacco); establishes a demonstration grant program to develop strategies for smoking cessation in medically underserved communities; increases civil penalties for certain violations of restrictions on the sale of tobacco products; and requires the Government Accountability Office to study e-cigarettes.