How Long Should You Fast Before Having A Blood Test?

That will all depend on what time your bloodwork will be. There should be no food and liquid in-take (except regular medicatio) about 8 to 10 hours before bloodwork. So you always get an answer no food and liquid after midnight thinking that you're going to have your test anywhere between 8 to 10a.m. The following morning.11 to 12 hours before bloodwork maybe pushing the fasting period.there is such a thing as overfasting and this will mess up the bloodwork.

My physician requires no food after midnight the night before the test.  Maybe that is not clear???  If you are going to have the test done on Friday, do not eat after midnight on Thursday night.  They tell me to go ahead and take medication with small amount of water and my physician even allows me to have black coffee or water the morning of the test.  
  

It depends on what bloodtest is ordered.  If it is fasting bloodwork the above answer is correct.  No food or drink after midnight the night before the test is to be done.  You may take your medications you usually take in the am with a small amount of water.  If it is non-fasting bloodwork no fasting is necessary.