How to Prepare for Your Blood Test

Are you getting your blood drawn? These tips will make it easier.

Whether you’re a little anxious or an old pro, some simple tips can make the test go more smoothly.

Know what kind of test you’re getting and special directions

Blood draws are a common diagnostic tool. Some are done yearly, while others are occasional to diagnose specific conditions or learn how new medicines affect your body.

“When your doctor orders a test, learn what the test is for and what you may need to do to prepare, like fasting for 8 hours,” says Gustaaf de Ridder, MD, PhD, system director for transfusion services at Geisinger. “Try not to spend time before your blood draw worrying about it. Make your day as normal as possible.”

When you have to get a blood test, ask your doctor or health professional:

What tests am I having and what do they measure?
Do I need to fast or avoid certain foods?
Should I take my medications as usual?
What will happen during the procedure?
How and when will I get my results?

Geisinger offers more than 60 locations to get your blood tested. You can walk in or schedule an appointment by logging into MyChart/MyGeisinger.

Before the blood work, stick to your doctor’s guidelines

Many tests don’t need special preparation. But for others, you must follow your doctor’s directions. If you don’t, the test results will be inaccurate, and the medical lab will likely refuse to draw your blood that day.

You may need to fast

Fasting — which is defined as not eating for 8 to 12 hours and only drinking water — is needed before some tests. Ask your doctor if you need to fast and for how long.

You’ll usually need to fast before these common blood tests:

Basic metabolic panel
Blood glucose
Cholesterol (lipid)
Iron
Liver function
Renal (kidney) function
Thyroid function
Triglycerides test

“Routine annual blood draws usually require fasting,” says Dr. de Ridder.

Not fasting? Eat well.

If you don’t need to fast for your test, do just the opposite. “Eat a good meal 1 to 2 hours before your blood work to prevent lightheadedness,” says Dr. de Ridder. To feel your best, consider doing these things beforehand:

Stay away from fatty or rich foods
Eat plenty of protein

However, don’t eat right before your appointment if you think you might get nauseous when your blood is drawn.

Drink plenty of water

Starting at least the day before your blood test, drink water. Staying hydrated helps increase your blood volume, plumping up your veins for an easier draw.

Avoid coffee, tea, energy drinks and other caffeinated drinks, which can dehydrate you. “Being dehydrated can make the blood draw more difficult. It can also change the levels of electrolytes and other things in your blood, which can make the tests impossible to interpret or affect the results,” Dr. de Ridder says.

Also avoid these common tasks

“There are some common daily behaviors that can throw off results,” says Dr. de Ridder. “Check on any restrictions with your doctor before the test.”

You might be asked not to:

Chew gum or use breath mints or lozenges
Smoke, vape or use e-cigarettes or nicotine gums
Exercise vigorously
Take vitamins or supplements
Drink alcohol

Often, drinking even black coffee or plain tea is discouraged. The caffeine can dehydrate you, making the test more difficult. Ask your healthcare provider for information.

Should you take medications before a blood draw?

Usually you can take medications, even while fasting for the blood test. If you need to take your medication with food, check with your doctor first. You might want to wait. Your doctor may also tell you to skip other medications that could affect the results.

You can take blood thinners and get your blood tested

“Blood thinners — like warfarin, Eliquis^®, Xarelto^® or Plavix^® — make your blood take longer to clot,” Dr. de Ridder says. “It’s still safe to have your blood tested. In fact, it might be required while you take some blood thinners.”

Tell your nurse or phlebotomist (a person who draws blood) that you’re on blood thinners. They can prevent excess bleeding and make you more comfortable.

During your blood draw

As you walk into the lab, these tips will make your visit easier:

Review your labs. As you start, check that all the labs you expect are ordered and they’re taking enough blood.
Think you might faint? Speak up. If you’ve fainted during blood draws in the past, tell the nurse or phlebotomist. They can have you lie down or position you differently to reduce your risk of falling.
Ask for a smaller needle. You might be anxious because other healthcare providers have had trouble getting a good stick for a blood test. Ask your phlebotomist to use a thin butterfly needle.
Take a deep breath and relax. Feeling anxious about your test? Take 5 or more calming, slow, deep breaths. Breathe all the way into your belly. You can also ask the person drawing your blood to explain what they’re doing. Uncertainty can be stressful. “The calmer you are, the easier the draw will be, and the quicker you’ll be out of there,” Dr. de Ridder notes.
Don’t look — distract yourself instead. Does a blood draw make you queasy? Look anywhere but at the needle. Read, look at your phone, listen to music or chat with your phlebotomist. Professionals who draw blood understand it can be difficult for some people. They’re usually experts at distraction and can put you at ease.

After the blood draw

Reward yourself with a snack

After your blood work, eat something small to keep your blood sugar up. Good options include:

Granola bars
Nuts
Fruit

Bring your snack to your appointment so you can enjoy it as soon as you’re done.

What to do with the bandage after the blood test

After your blood test, the medical technician will apply a bandage. You can take it off in an hour. If bleeding starts up again, apply slight pressure until it stops and put on another bandage. Some bruising is normal and should go away after a few days.

When can I see my results?

If you’re a Geisinger patient, you can view most Geisinger test and lab results with the MyChart mobile app or at home with MyGeisinger. Learn more about MyGeisinger and sign up today.

Your doctor’s office may also call you to share the results. Sometimes the blood tests show you need to start or change a medication, visit your healthcare provider or have more testing.

“Make sure you understand any abnormal test results. If you don’t hear from your doctor, you should ask them to explain what your test results mean for your health,” says Dr. de Ridder.