I tell everyone, principally to keep myself honest but I do agree with Bob the Ostrich Guy, it clears a lot of needless prevarication out of the way.
You can also go the, I don't drink because...
I have a allergy
It doesn't agree with my tummy
I'm taking an antibiotic
It makes me break out in handcuffs
What you do, or do not, tell people is, ultimately, your business. I make sure I'm feeling solid before I put myself in a situation like that and have a way to make a quick exit. If I'm not feeling solid, i.e. stressed, upset, overly elated (good feelings can lead to an incautious moment, too) I make my excuses and stay home.
Stay safe.