How to Prepare for a Blood Test

Healthcare professionals may request a blood test for various reasons. From monitoring medication levels to evaluating results for disease diagnosis, blood tests play a crucial role in your healthcare routine. They are particularly important for assessing the function of organs like the liver and kidneys, diagnosing diseases, identifying health risks, checking current medications, and evaluating blood clotting ability. Depending on the type of test ordered, you may need to have your blood drawn at a clinic or a nearby lab. Below are some steps to help you prepare, both physically and mentally, for a blood test.

Consult your doctor. It's important to know which specific test your doctor has ordered. Some tests require special preparation for accurate results, including the following common examples:

• The Glucose Tolerance Test, which requires fasting before going to the lab. You may also need to stay at the lab and have blood drawn every 30-60 minutes. This process can take up to 5 hours.
• The Fasting Blood Sugar Test is done after you fast and only drink water for 8-12 hours. This is usually scheduled in the morning to avoid fasting all day.
• The Serum Lipid Test, or cholesterol test, sometimes requires you to fast for 9-12 hours before the blood draw.
• The Blood Cortisol Biochemistry Test requires you to stop exercising the day before, lie down for 30 minutes, and fast for an hour before the test.

Discuss the medications you are taking. Certain substances can interfere with your blood test, so you may need to stop taking them prior to the test. Depending on the test, prescribed medications, recreational drugs, alcohol intake, vitamins, blood thinners, or over-the-counter drugs could alter the results.

• Your doctor will decide whether you should wait 24 - 48 hours before the test or if the medications you are taking will not significantly affect the results.

Avoid certain activities. Depending on the activity, some tests may not yield accurate results if affected by physical exertion or intense exercise done shortly beforehand, dehydration, smoking, herbal teas, or sexual activity.

• You may be asked to temporarily refrain from one of these activities before your blood test.

Consult your doctor for guidance. Many tests do not require special preparation before drawing blood. However, if you are uncertain, it is always best to ask. If your doctor hasn’t provided specific instructions, proactively inquire to minimize the risk of inadequate preparation before the test.

Stay hydrated. Proper hydration helps make blood collection easier. It makes veins more prominent and easier to find, and your blood will flow more smoothly into the tube. If fasting is required, make sure to drink plenty of water the day before.

• This means you might need to get up in the middle of the night to use the bathroom, but being truly hydrated will make the blood test process much smoother.

Warm the blood draw site. Before you are ready to have your blood drawn, warm the area where the blood will be taken. Apply a warm compress for 10-15 minutes to improve blood circulation in that area.

• Dress in warmer clothing than usual when going for your blood test. This will increase skin temperature, improve circulation to the site, and make it easier for the technician to locate the vein.

When speaking with the blood sample collector, if you find yourself deviating from the preparation guidelines before the blood draw, be sure to inform the collector as soon as you arrive. If the deviation is significant enough to affect the test results, you may need to return on another day to provide a new sample.

• Notify them if you're allergic to or sensitive to latex, which is commonly found in gloves and bandages used during blood collection. Some individuals have dangerous latex sensitivities that can be life-threatening. If you are aware of your sensitivity, inform the doctor and the blood collection staff so they can use latex-free equipment for your safety.

Relaxing your mind can make all the difference. Blood tests can cause significant anxiety or stress, which unfortunately leads to higher blood pressure, vein constriction, and makes the blood collection more difficult.

• Knowing how to reduce stress can help improve the preparation process and increase the chances of the blood collector finding a vein on the first attempt.
• You can try deep breathing exercises or repeat calming affirmations such as: "This will be over quickly. Many people have had blood drawn. I can do this too." Refer to the "Stress Reduction Techniques" section in this article for more detailed guidance.

Acknowledge your fears. Before meeting with your doctor, admit that you might be nervous about having blood drawn. You may also have a fear of needles. Between 3% to 10% of the population experience needle phobia (trypanophobia) or fear of injections (belonephobia).

• Interestingly, 80% of people with a needle phobia have family members (parents, siblings, children) who also share this fear. This suggests that the phobia might have a genetic component.

Ask about EMLA. If you've previously had blood drawn and found the process especially painful, inquire with your doctor about using EMLA. This is a topical anesthetic applied to the blood draw site 45 minutes to 2 hours prior to the procedure.

• If you're particularly sensitive to pain, ask whether EMLA could be a suitable solution for you.
• EMLA is commonly used in children, but it is less frequently used in adults because it requires a long period to take effect.
• You could also ask about "Numby Stuff," a combination of lidocaine, epinephrine, and a mild electrical current to numb the area, which takes effect in about 10 minutes.

Understand the process's starting point. To prepare yourself mentally for blood collection, it's important to know the procedure. The phlebotomist will wrap a rubber tourniquet around your upper arm, just above the elbow, and ask you to make a fist. For standard blood tests, blood is typically drawn from a vein in the arm or from a fingertip.

• The tourniquet increases blood flow to the arm, allowing blood to move from deeper arteries, but only a small amount can flow out. This makes the veins expand, making it easier to locate and draw the blood.

Know how blood is drawn. Regardless of where it's done, the procedure for drawing blood is fairly consistent. A syringe, usually connected to a small tube, is inserted into the vein. Once enough blood is collected, the tube is removed and automatically sealed.

• If more tubes are needed, the needle stays in place and another tube is attached to the end of the needle. Once all the necessary tubes are filled for your test, the phlebotomist will remove the needle and apply a small gauze pad to the puncture. They will ask you to press on it while preparing to send the blood to the lab.
• You may need to apply a band-aid to the gauze to stop any bleeding.
• The entire process typically lasts 3 minutes or less.

Deep breathing. If the thought of blood collection makes you uneasy, it’s important to relax. Focus entirely on your breath, inhaling deeply. Deep breathing triggers the body's relaxation response. Breathe in slowly, counting to four, then exhale slowly, counting from one to four.

Acknowledge your anxiety. Anxiety is just a feeling, like any other. It only takes control when you allow it to. By acknowledging it, you take away its power. Trying to ignore it only makes it stronger.

Recognize that your mind may be deceiving you. Anxiety is a trick that creates real physical consequences in your body. Excessive worry can trigger panic attacks with symptoms similar to a heart attack. Understand that anxiety, whether small or large, is just a mental illusion, and recognizing this can help alleviate the pressure and responsibility of self-care.

Ask yourself questions. When anxious, try to ask yourself a few questions to assess the true severity of the situation. Anxiety can amplify irrational thoughts, but asking concrete questions that require real answers can help sharpen your awareness. Consider asking yourself questions like:

• What is the worst that could happen when getting blood drawn?
• Are my worries realistic? What is actually likely to happen to me?
• What are the chances of the worst-case scenario happening?

Practice positive self-talk. You will follow what you tell yourself, even when you don’t think you’re capable. Speak aloud and repeat to yourself that you are strong, that you can handle the situation, and that nothing terrible will happen. This can help reduce the tension you’re feeling.

Have a light snack. If you fasted before your blood draw, it’s a good idea to bring a small snack to eat afterward. Also, carry a bottle of water and a non-perishable snack. This will help you manage until you can have a full meal.

• Peanut butter crackers, a peanut butter sandwich, a handful of almonds or walnuts, or whey protein are all easy to carry and provide enough protein and calories to hold you over until your next meal.
• If you forget to bring something to eat, ask the staff at the blood collection site. They may have crackers available for this very purpose.

Ask about the wait time for results. Some tests are completed within 24 hours, while others may take a week or longer, especially if the blood needs to be sent to a specialized lab. Talk to your doctor about the process of result transfer. In some cases, the clinic may not notify you if the results are normal. If the results are sent, ask how long it takes for the clinic to receive them.

• Request notification, even if the results are normal. This ensures your results aren’t "lost"—leading to no notification despite abnormal findings.
• If the results are supposed to be ready and you haven’t been notified after 36 to 48 hours, contact the doctor’s office.
• Ask about the doctor’s office online notification system. They might provide a website where you can register, and results will be sent to you electronically.

Be aware of bruising. The most common side effect of blood draws is bruising or hematoma at the needle insertion site. Bruising may appear immediately or within 24 hours of the blood draw. Factors contributing to hematoma include blood leakage from the vein during needle insertion, causing blood to leak into the surrounding tissue. It can also be due to bleeding disorders or blood thinners, which increase the risk of bruising or hematoma during blood collection.

• Apply pressure to the blood draw site for five minutes or longer, if necessary, to stop bleeding and generally reduce the risk of hematoma.
• Bleeding disorders, the most well-known being relatively rare, come in two types: A & B.
• Von Willebrand disease (VWD) is the most common bleeding disorder affecting clotting ability.
• If you have a bleeding disorder, inform the doctor and the phlebotomist before the blood draw.

Ask about the potential for inaccurate results. Several factors can cause discrepancies in blood test results. Prolonged tourniquet use can lead to blood pooling at the draw site, increasing blood concentration and potentially causing either false-positive or false-negative results.

• To avoid blood pooling, the tourniquet should not be left on for more than one minute.
• If more than a minute is needed to locate a vein, the tourniquet should be removed and reapplied after two minutes, right before the needle insertion.

Discuss hemolysis with the phlebotomist. Hemolysis isn’t a complication within you; it’s an issue with the blood sample. Hemolysis occurs when red blood cells break down, and other components leak into the serum. This makes the blood unsuitable for testing, requiring a new sample. Hemolysis typically happens when:

• The tube is shaken too vigorously after removal from the needle.
• Blood is drawn from a vein near an existing hematoma.
• A small needle is used, damaging red blood cells as they’re drawn into the tube.
• Your fist is clenched too tightly during the blood draw.
• The tourniquet is left on for more than a minute.