You generally need to fast for 8 to 12 hours before a blood test if fasting is required. During this fasting period, you should not eat or drink anything except water. This fasting helps ensure that the test results are accurate by preventing recent food or drink intake from affecting blood sugar, cholesterol, and other measurements
. Additional guidelines include:
- Avoid chewing gum, smoking, and exercising during the fasting period, as these can affect digestion and test results
- Drinking plain water is encouraged to stay hydrated and make blood draw easier
- Avoid alcohol for at least 24 hours before the test for best accuracy
- Not all blood tests require fasting; follow your healthcare provider’s specific instructions for your test
Many people schedule fasting blood tests early in the morning so that most of the fasting occurs overnight while sleeping
. In summary, fasting for 8 to 12 hours before a blood test is the standard recommendation, but always confirm with your healthcare provider for the exact fasting duration needed for your specific test.
