There are plenty of myths about how you can sober up fast. Believing them and going on to drive could land you a charge for operating while intoxicated (OWI).
There is nothing you can do to hasten getting alcohol out of your system. You just have to leave your body to do it at its own rate.
How long is that?
Firstly it is important to realize that your body does not treat alcohol like food. It does not digest it but seeks to expel it, considering it a toxin. About ten% of the alcohol leaves the body via sweating, urinating and breathing. The rest is left for the liver to deal with. This metabolizes alcohol at an average rate of around 0.015 g/100mL/hour.
So, provided you do not keep drinking, your blood alcohol content will drop by about 0.015% per hour. In some cases, that rate can be slower, due to liver problems, illness or certain medications you have taken; but you cannot do anything to speed it up.
The average rate given is also for an average male, so it will differ slightly from person to person and women tend to metabolize alcohol more slowly.
Caution is key
Allowing plenty of time between finishing your last drink and driving is the best way to avoid an OWI — short of not drinking before driving at all. That could mean you are still unfit to drive the morning after a big night. If you get it wrong and the police charge you, there may still be defense options available.