WHAT IS A BLOOD TEST? A Blood test is where a small amount of your blood is taken with a needle WHY DO I NEED A BLOOD TEST? You need a blood test so that your blood can be checked to see if you have an infection. The blood is checked in a place called a `laboratory` Some people have blood test to see if their medicine is working. WHAT HAPPENS? For Darren’s blood test story click here CAN I EAT BEFORE A BLOOD TEST? Unless you have been told that you should not eat before your blood test You are able to eat and drink what you like.