Preparing for a blood test: fasting, water and medicines

A little preparation can save you a second trip. Some tests give a reliable result only on an empty stomach, and a sample taken after breakfast may have to be taken again.

Do you need to fast?

Not for every test. Fasting is commonly needed for a fasting blood sugar test and often for a lipid (cholesterol) profile, usually for 8 to 12 hours before the sample is taken. Many other tests do not need it.

The instructions depend on the exact test, so tell us the test name, or show the prescription, when you book. We will tell you whether to come on an empty stomach and for how long.

If you are fasting, an early morning appointment makes the wait easier.

Water is usually fine

Plain water is normally allowed, even when you are fasting, and it makes the sample easier to take. Tea, coffee, milk and juice are not plain water: avoid them while fasting unless you have been told otherwise.

Do not stop your medicines on your own

Keep taking your regular medicines unless your doctor has told you to stop or delay a dose before the test. Some medicines can affect particular results, and your doctor is the one to decide. Tell us what you take when you come in.

If you have diabetes, ask your doctor how to manage fasting and your diabetes medicines, so your sugar does not fall too low.

What to bring

• your doctor’s prescription, if you have one
• a list of the medicines you take
• previous reports for the same test, if you have them

Where

The laboratory is at our Sayan clinic only. Our Chhaprabhatha-Variyav Road clinic is dental-only. If coming in is difficult, we can also collect the sample from your home.