Hello Dr. Terri Warren, I am a previously confirmed negative HSV-1 via western blot. I recently had a sexual encounter with 2 females of unknown status. We kissed (tongue) and I performed oral sex on them. Exactly 53 hours later I have developed a flat, open wound on the left side, bottom, of my lip near the corner of my lips (where top meets bottom). It is definitely off the corner, but very near it. I would like to add that in that 53 hour span I went from a hot climate (Mexico) to a cold one (northern Westcoast of United States). I also mouth tape when I sleep (for nasal breathing / better rest) and sometimes, in the past, it has led to cracking when peeling off, mainly when I have a pimple. What are the chances this is HSV-1 from the encounter? The open area is very small, not raised whatsoever. It's just an open wound. No tingling, fever, sore throat, tiredness, nothing. I'm wondering if it's from the change of climate and tearing off of the mouth tape when sleeping. It looks like cheilitis but it's not immediately at the corner so that's why I'm concerned. 

Chelitis is at the corner, by definition.  So probably not that.  However, if you are negative for both HSV 1 and HSV 2 by western blot, I think if you acquired a new HSV 1 infection your symptoms might be more dramatic and noticeable and start with a blister rather than an open sore.  And the mouth tape sounds like it could be playing a role here as well, yes.  Not sure about the climate playing a role, though.  I would keep an eye on it and see if anything forms around it, like water blisters or you get more open areas.  If possible, you could get it swab tested if things progress.  But just based on what you've said here, HSV seems an unlikely cause of the open wound, to me.  ---