Borderline almost passed out from low amount of alcohol.

I’m 21M and recently went to the bar for the 5th time ever. I got this drink with low alcohol content. I drank about 8oz of it then almost passed out. I know alcohol is supposed to turn your body off in a way, but still. I just find it odd that is what happened after such a small drink. This happened last time but was more like me getting a little sleepy.