Ticket 03 of 07

Can I eat before a blood test, and does coffee count?

In one line. Only the lab that ordered the test can say; when the order says fasting, plain water is the one thing nobody argues about, and coffee is exactly the thing people argue about.

The morning of a blood draw is a small ordeal that nobody prepares a man for. He has an appointment at eight, an empty stomach since the night before, and a coffee maker he has walked past three times. The question at the counter is always the same, and the counter always gives the same honest answer: it depends on which tests were ordered, and the sheet that came with the order is the authority, not the receptionist and not this page.

Fasting, when it is asked for, means no food and no drink with calories for a set number of hours, most often through the night. Plain water is allowed and, in fact, welcome: a person who drinks a glass or two in the morning tends to have an easier time at the needle, because the vein is simpler to find. Chewing gum, mints, juice and a splash of milk all break the fast in the lab's eyes, whatever they feel like to the person.

Black coffee is the grey zone. Some labs tolerate it for some tests, others ask that it wait, and the safest reading of a fasting order is that it waits too. The practical move is to ask when the test is booked, write the answer on the order, and then book the earliest slot available so the fast ends at a civilised hour. Bring the coffee in a flask and drink it in the car afterwards; it tastes better earned.

Two more details make the morning kinder. Keep taking whatever was prescribed unless the person who ordered the test said otherwise, and say at the counter if you tend to feel faint at the sight of a needle, so the chair can be tilted back before, not after. Then eat something as soon as the plaster is on.

Where the desk stops. This page describes how a fasting order is usually read; it does not override the instructions that came with yours. Those instructions, and anything about the medicines you take, belong to the lab and to your physician.