Nicotine-related syncope?

Is it possible to faint as a result of alcohol/nicotine use?  My boyfriend has now on two occasions lost consciousness after smoking (once through hookah, once cigar) combined with light alcohol use (few drinks).  He's not a smoker in general, so such a mixture is rare.  The first time, there were two fainting episodes within a few minutes of each other, the second occurring when he tried to get up.  I tried to catch him and his body was slightly shaking (seizure?).  On both occasions, his heart was racing immediately afterward and he did not recall anything surrounding the event.  Most recently he does not remember more than an hour surrounding the fainting spell.  He's hesitant to seek medical evaluation.  Could this be just related to nicotine/alcohol?  What signs would point to something more complicated/serious?

Thanks for any advice you may have.