Is fasting required for a routine blood test?

A complete blood count (CBC) generally does not require fasting. The CBC primarily evaluates blood cell counts, including red blood cells, white blood cells, and platelets, as well as classifications such as neutrophils. These indicators are not directly affected by food metabolism, so eating before the test usually does not affect the accuracy of the results. Although fasting is not required for a CBC, it is advisable to avoid excessive water intake before the test to prevent blood dilution, which may affect the results. Additionally, if other tests that require fasting—such as blood glucose, lipid profile, or liver function tests—are also being performed, you should follow your doctor's instructions for fasting preparation. Moreover, staying relaxed and avoiding excessive tension or anxiety can also help ensure accurate test results. After blood collection, it is important to apply pressure to the puncture site and avoid rubbing it to prevent worsening of bleeding.