If i drunk last nite can i still take my metronidazole 500mg?

Ideally : You should avoid alcohol consumption until 48 hours after completion of your metronizadole treatment course, to help avoid some of the undesirable symptoms that may arise from taking both together.

Disulfiram reaction: Is the issue here. You will feel sick if you combine the two. While on Flagyl, do NOT drink alcohol. Not just because of the reaction, but also because Flagyl is metabolized by liver. After you stop taking med, don't drink for additional 3 days or so. If you had one or two drinks, early in the night, don't feel hungover, you may be safe from the reaction. Go to ER if you get sick with vomiting.