Alcohol and caffeine

You feel the effects of alcohol less after using caffeine. For example, think about energy drinks. Because of the caffeine you can  drink more and longer. On the other hand, the alcohol can help to weaken the effect of the caffeine. You are more relaxed, but a bit more awake. This can also cause you to drink more caffeine than if you didn’t drink alcohol. You’re more likely to overestimate yourself.
Keep in mind that if you drink faster and more, the hangover is also considerably bigger. This is also because the combination also causes the body to lose more fluid than if you only drink alcohol or caffeine.