E-cigarettes are popular and unregulated. Patient-provider communications concerning e-cigarettes were characterized to identify patient concerns, provider advice and attitudes, and research needs.An observational study of online patient-provider communications was conducted January 2011-June 2015 from a network providing free medical advice, and analyzed July 2014-May 2016. Patient and provider themes, and provider attitudes toward e-cigarettes (positive, negative, or neutral) were coded qualitatively. Provider attitudes were analyzed with cumulative logit modeling to account for clustering. Patient satisfaction with provider responses was expressed via a Thank function.An increase in e-cigarette-related questions was observed over time. Patient questions (N=512) primarily concerned specific side effects and harms (34%); general safety (27%); e-cigarettes as quit aids (19%); comparison of e-cigarette harms relative to combusted tobacco (18%); use with pre-existing medical conditions (18%); and nicotine-free e-cigarettes (14%). Half of provider responses discussed e-cigarettes as a harm reduction option (48%); 26% discussed them as quit aids. Overall, 47% of providers' responses represented a negative attitude toward e-cigarettes; 33% were neutral (contradictory or non-committal); and 20% were positive. Attitudes did not differ statistically by medical specialty; provider responses positive toward e-cigarettes received significantly more Thanks.Examination of online patient-provider communications provides insight into consumer health experience with emerging alternative tobacco products. Patient concerns largely related to harms and safety, and patients preferred provider responses positively inclined toward e-cigarettes. Lacking conclusive evidence of e-cigarette safety or efficacy, healthcare providers encouraged smoking cessation and recommended first-line cessation treatment approaches.