you might notice some mild ph changes secondary to no longer retaining as much carbon dioxide due to the lack of smoke in the e cigs. that would be very transient however becuase between your kidneys and lungs your body keeps your ph pretty stable. From whati have read on the subject so far the ingrediants are pretty safe. there is a wide array of drug interactions with the polyethylene glycol, but you would have to be more specific with a drug to ask but mostly with blood pressure medications and antidepressants/antipsycotics.