Fasting for Lab Tests
Some lab tests work best when you fast (do not eat or drink anything except water) before your blood draw. If you are not sure whether your lab test requires fasting, check with your provider before your appointment.
How long do I need to fast?
Most fasting labs require you to fast for 12 hours before your blood draw. Your provider may give you different instructions based on your test or medical history.
What can I have during the fast?
- Water is allowed.
- You may take essential prescription medicines unless your provider tells you otherwise.
During the fasting period, please do not:
- Eat any food or candy
- Drink coffee, tea, juice, milk, soda or flavored beverages
- Chew gum
- Use tobacco products
Which tests usually require fasting?
Your provider will tell you if your lab test requires fasting. Some common tests that may require fasting include:
- Glucose tests, including glucose tolerance testing
- Lipid profiles (cholesterol, HDL, LDL, triglycerides)
- Vitamin levels
- Homocysteine
If You Have Questions
If you have questions or are unsure whether you should fast, please contact your provider. They are the best resource for information about your testing instructions.
