What are the side effects of the e_cig if it contains zero nicotine?

Still toxic: E-cigarettes are not "safe." they are not zero nicotine, they are zero smoke. The nicotine keeps you addicted. Many adverse effects, including increased airway resistance (lowered ability to breathe), starts right away upon use. Also toxic ; carcinogenic chemicals are still inhaled (such as formaldehyde ; propylene glycol). Take the leap ; quit! try smoking cessation class or nicotine anonymous.