Can You Drink Tea Before a Fasting Blood Test?

Some common blood tests require you to fast beforehand to help make sure the test results are as accurate as possible. You can typically still drink water during this period, but is drinking tea allowed before a fasting blood test?

To help you best prepare for your doctor’s appointment, here’s what to know about drinking tea before a blood test, plus tips for how to manage your pretest fast.

Can You Drink Tea Before a Fasting Blood Test?

Making the Fast Bearable

Even if you aren’t able to have a cup of tea, it’s still possible to make a fast more manageable: Dana Neutze, MD, PhD, associate medical director of the University of North Carolina Family Medicine Center at Chapel Hill and an assistant professor in the department of family medicine, suggests trying to schedule your blood work for as early in the day as possible.

“I recommend people come in first thing in the morning, so that they don’t have to wait too long,” she says. And staying well hydrated may curb creeping hunger pangs, she says.

Common Fasting Blood Tests

• Glucose tests, which measure your blood sugar
• Lipid tests, which measure your cholesterol and triglyceride levels
• Basic metabolic panels, which measure electrolytes, blood sugar, and kidney function markers
• Gamma-glutamyl transferase tests, which measure liver function

Fasting can also be important before certain triglyceride and cholesterol tests, for a similar reason. “Triglyceride levels are the component of cholesterol that are most affected by fasting or not fasting,” Neutze says.

Cholesterol tests don’t always require fasting. “Nowadays, we can look at many aspects of cholesterol, even if you’re not fasting,” Neutze says. “If I have a patient whose triglyceride levels I know have been fine in the past, I’ll order a non-fasting test to check other cholesterol components.”

The Takeaway

• You should not drink any type of tea before a blood test that requires fasting, which typically means not drinking tea for 8 to 12 hours before your test.
• Tea contains compounds that can alter the results of some blood tests. If you do drink tea before your test, let your doctor know, as they may need to rerun the test.
• Tests that often require fasting include those for blood sugar, cholesterol, metabolic function, and liver function.
• Before your blood test, ask your doctor for specific instructions about fasting, including which beverages you can and can’t have beforehand.