For a blood test that requires fasting, the typical fasting duration is between 8 to 12 hours before the test. Some specific tests, like lipid panels (cholesterol and triglycerides), may require fasting for up to 12 to 14 hours. During the fasting period, only water should be consumed — no food, drinks other than water, gum, or smoking is allowed. The fasting is usually done overnight, with the blood test scheduled for the morning. Medications should generally be taken as usual unless instructed otherwise by the doctor. If a person has diabetes or other health conditions, they should consult their doctor for special instructions regarding fasting. The fasting requirement ensures more accurate test results by eliminating the effects of recent food or drink intake on blood composition.
