What is Zyn? Doctors share health concerns of the popular and controversial nicotine pouch

It's not a cigarette or vape, because there's no smoke. And it's not chewing tobacco, because there's no tobacco or spitting required. It's called Zyn, a brand of nicotine pouches that are gaining popularity, especially among younger demographics. 

Some proponents of the pouches say it gives them a rush, while others hope it'll help them kick a smoking habit. So-called "Zynfluencers" can be seen popping the little white pouches between their gums and cheeks on social media.

Others, however, are warning against the product, noting health concerns. In addition to nicotine, the pouches also contain plant-based fibers, sweeteners and flavorings like cinnamon, citrus and coffee.