Can I get a blood test if I havent eaten?

Shortly after you eat, the chemicals in your blood undergo changes. These changes can also occur if you do not eat for long periods. It is important to fast correctly, to obtain reliable blood test results. Fasting means nothing to eat or drink (except water) for 10–16 hours before your blood test.

How long can you go without eating for a blood test?

You usually need to fast for 8–12 hours before a test. Most tests that require fasting are scheduled for early in the morning. That way, most of your fasting time will be overnight.

What happens if you dont eat before a blood test?

If you don’t fast before a test that requires it, the results may not be accurate. If you forget and eat or drink something, call your provider and ask if the test can still be done. Some tests can be analyzed with a notation that it isn’t fasting and results may vary.

How do I know if my blood test is fasting?

Fasting means you don’t eat or drink anything but water usually for 8 to 12 hours beforehand. If your appointment is at 8 a.m. and you’re told to fast for 8 hours, only water is OK after midnight. If it’s a 12-hour fast, avoid food and drink after 8 p.m. the night before.

Does what you eat the day before affect a fasting blood test?

McKnight also mentioned the food or drinks you consume the day or night before a blood test does not impact your test results, unlike what you eat or drink the morning of your test. “It’s recommended that you avoid coffee and other liquids during your fast,” McKnight said.

Can you brush your teeth before a blood test?

Fasting means that, with the exception of water, you refrain from eating or drinking for a minimum of 8 hours (10 to 12 hours is preferable) prior to the test. This means no coffee or tea beforehand, but taking your vitamins or medications is okay. Brushing your teeth or using mouthwash won’t influence the test.

How much water should I drink before a blood test?

This is generally the case for blood tests and surgeries. If your phlebotomy specialist says it is OK to drink water before getting blood drawn, try to drink the recommended daily amount of water, which is 64 ounces. Before you donate, drink a glass of water that’s about 16 ounces.