How to Prepare for a Blood Test

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Medical professionals order blood tests for a variety of reasons. From monitoring medication levels to evaluating your results in the course of diagnosing a medical condition, blood work can be an essential component of your health care. Specifically, blood tests are done to evaluate the function of certain organs, such as the liver or kidneys, diagnose disease, determine risk factors, check medications you are taking, and assess blood clotting. [1] Depending upon the type of blood test ordered, you’ll either have your blood drawn in their office or at another laboratory in your area. There are multiple things you can do to prepare yourself for a blood test, both mentally and physically.

Method 1
Method 1 of 4:

Preparing Physically For a Blood Test

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  1. Let your doctor know about any symptoms you've been experiencing, and ask if there are any specific blood tests that could help with investigating the cause. [2] You need to know about the specific blood tests your doctor is ordering. Some blood tests will require special preparation to get accurate results.
    • Some tests require fasting. This means no food or drink, other than plain water, for at least 8 hours. Juice, tea, or coffee should not be consumed because the sugars and calories in these beverages may cause inaccurate test results. [3]
    • In some cases, the glucose (blood sugar) and serum lipid (cholesterol) tests require fasting, but may not be necessary in other cases. Your doctor may order these tests as random, meaning fasting isn't needed. [4]
    • The oral glucose tolerance test (OGTT) first involves a baseline fasting sample draw. Then, you'll consume a flavored drink containing a certain amount of glucose, and undergo additional blood draws over a period of several hours. The purpose is to see how fast your body metabolizes glucose and is often part of a pre-diabetes investigation. Make sure you are able to stay in the lab for the whole duration. [5]
    • Certain hormone tests such as cortisol, aldosterone, and renin require you to refrain from exercising the day before, lie down for 30 minutes before the test, and refrain from eating or drinking for 1 hour before the test. [6]
    • Tests to be done at a specific day or time. For instance, testosterone may be ordered as being drawn in the morning before 10 a.m., and progesterone should be tested on a specific day of a woman's menstrual cycle. [7]
    • Tests for monitoring certain medications, such as tacrolimus, are ordered as either pre-dose (before the next dose) or post-dose (2 hours after you take the medication). Be prepared to tell the lab staff the date and time of your last dose and the frequency with which you take the medication. [8]
  2. There are certain substances that can alter blood tests, which you may need to stop before your blood test. Prescription medications, recreational drugs, alcohol intake, vitamins, blood thinners, or over-the-counter medications can often change the results of a blood test, depending on what the blood test is for. [9]
    • Your physician can determine if you should wait 24 to 48 hours to have the blood work done or if what you have taken will not significantly alter the blood test results.
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  3. There are some blood tests that can be compromised based on your activities. These tests can be altered by recent physical activity or heavy exercise, undergoing dehydration, smoking, drinking herbal teas, or sexual activity. [10]
    • You might be asked to refrain from some of these activities prior to taking a blood test.
  4. Many routine tests do not require special preparation prior to getting your blood drawn. However, when in doubt, ask. If your physician does not give you any special instructions, it is important that you ask in order to reduce the potential that you arrive for the test without preparing sufficiently.
  5. Being sufficiently hydrated makes the blood draw easier because it increases your blood volume and makes your veins more prominent to the touch. If you need to fast from water as well, be sure you are very hydrated from the day before. [11]
  6. Before you get ready to take a blood test, warm the extremity where the blood will be drawn. Use a warm compress over the area for 10 to 15 minutes to improve the blood flow to that area.
    • Wear warmer than normal clothes for the season when you go in to get your blood drawn. This increases your skin temperature, increases the blood flow to the area, and makes it easier for the phlebotomist (the person who draws your blood) [12] to find a good vein.
  7. Lab staff are trained health professionals and will help guide you through the procedure safely. Understand that for the sake of obtaining accurate test results, staff may not be able to proceed with the blood draw if you've deviated from any preparation requirements. [13]
    • Mention if you are allergic or sensitive to latex. Latex can be found in gloves, tourniquets, and bandages, and an exposure can be life-threatening in a person with an allergy or sensitivity. It is important to notify both your doctor and the phlebotomist so they can use latex-free equipment. [14]
    • Let the staff know if you're taking blood thinners such as warfarin (Coumadin) or apixaban (Eliquis). Since these medications prolong the time it takes your blood to clot, you and/or your phlebotomist will need to hold very firm pressure on the gauze for at least 5 minutes after the procedure to stop the bleeding. [15]
    • If you have a history of feeling weak, sick, or faint during or after blood tests, you should definitely disclose this information to the lab staff. Phlebotomy chairs are designed with a sturdy armrest that swings over the lap to prevent fainting patients from falling to the floor. Most labs have beds, so you can ask to have your blood drawn while lying down. [16]
    • Don't be afraid to offer helpful hints if you know you're a "hard stick" or your veins tend to be hard to find. Phlebotomists have the technical knowledge and skill, but ultimately you know your body more than anyone else. If you know, let the staff know which arm or hand is most likely to cooperate, which vein is easier to find and draw from, or which type of needle tends to be most effective. [17]
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Method 2
Method 2 of 4:

Preparing Mentally For a Blood Test

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  1. Blood tests can increase your stress level or anxiety when you are nervous about the test. Unfortunately, becoming stressed increases your blood pressure, constricts your veins, and makes getting your blood drawn more difficult. If you look and sound anxious, you're probably making your phlebotomist feel more pressured and anxious as well. [18]
    • Knowing how to reduce your stress can help improve your preparation for the test and increase the likelihood that the phlebotomist will find the vein the first time.
    • You could try deep breathing exercises or repeating a calming phrase, such as "This will be over very soon. Plenty of people have blood drawn. I can handle this." Look at the "Stress Reduction Techniques" section of this article for more tips.
  2. Before you go to the doctor to have your blood taken, recognize that you might be anxious about having your blood drawn. You may also have a fear of needles. Between three and 10 percent of the population has a fear of needles (Belonephobia) or a fear of all injections (Trypanophobia). [19]
    • Interestingly, 80% of people with a phobia of needles report that they have a first-degree relative also has a strong fear of needles. It's possible this fear is partially genetic.
  3. If you have had your blood drawn before and know that it is particularly painful for you, ask your doctor for an EMLA (Eutectic Mixture of Local Anesthetics). This is a cream which is put on the draw site between 45 minutes to 2 hours before the blood draw to numb the area. [20]
    • If you know that you are susceptible to pain, ask if EMLA is an option for you. [21]
    • EMLA is commonly used for children, but it is much less common for use by adults because of how long it takes for the medications to take effect in comparison to the actual duration of the blood draw. [22]
    • You can also ask about "Numby Stuff," a proprietary topical preparation that includes a combination of lidocaine and epinephrine and a mild electrical current to numb an area. It works in about 10 minutes.
  4. To feel better mentally about having blood drawn, it helps to have an understanding the procedure. The phlebotomist will sanitize their hands and put on a new pair of gloves as part of standard infection control procedure. Next, a flat elastic band (tourniquet) is tied somewhat tightly around your arm to compress your veins and engorge them with blood, which will make them easier to find. During a typical blood test, blood is usually drawn from a vein on the inner part of your elbow, the underside of your forearm, or the back of your hand. [23]
  5. The blood is drawn in similar ways, no matter where you get it done. A needle will go into your vein, which is usually attached to a small tube. When there is enough blood the tube, the tube is taken off, which seals automatically. [24]
    • If more tubes are required, the needle remains in place and another tube is put on the end of the needle. Once all the tubes needed for your blood tests are filled, the phlebotomist will remove the needle and put a small gauze over the area. She will ask you to put pressure on the area while they prepare the tubes to go to the laboratory.
    • After the needle is taken out, a bandage or piece of gauze is placed over the puncture site to stop the bleeding. [25]
    • The whole process usually takes 5 minutes or less. [26]
    • If your doctor has requested blood cultures, the procedure for collecting these is slightly different: more time is spent cleaning your arm, different bottles are used, and one poke on each arm is required. [27]
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Method 3
Method 3 of 4:

Using Stress Reduction Techniques

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  1. If you are having a hard time with the idea of getting your blood drawn, you need to relax. Take a deep breath and focus all of your attention on breathing. Deep breathing activates the body’s relaxation response. Inhale slowly to the count of four and then exhale slowly to the count of four. [28]
  2. Anxiety is just a feeling like any other feeling. Feelings only have control when you give them control. When you accept that you are anxious you take the power away from the feeling. If you try to get rid of the feeling it becomes overwhelming. [29]
  3. Anxiety is a trick of the mind that has real physical consequences. Enough anxiety can produce a panic attack, which can mimic a heart attack. When you understand that your anxiety, no matter how little or big, is little more than a trick of the mind it helps reduce the pressure and responsibility of caring for yourself. [30]
  4. When you are anxious, ask yourself several questions to determine exactly how bad the situation really is. Anxiety can increase the number of outrageous ideas you’re having while asking yourself specific questions that require realistic answers can increase your awareness. Ask yourself questions such as: [31]
    • What is the worst thing that can happen when they draw my blood?
    • Is what I’m worried about realistic? Can it really happen to me?
    • What is the likelihood that the worst thing will happen?
  5. You will hear what you say to yourself, even when you don’t think that you do. Talking out loud and repeating that you are strong, can handle the situation, and that nothing bad will happen will help to reduce your feelings of anxiety. [32]
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Method 4
Method 4 of 4:

Knowing What Happens After a Blood Test

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  1. If you were required to fast prior to the blood test, you’ll want to bring a snack for after the test. Also bring a bottle of water and a snack that doesn’t require refrigeration. This will tide you over until you are able to eat a meal.
    • Peanut butter crackers, a peanut butter sandwich, a handful of almonds or walnuts, or whey protein are all easy to transport and will give you some protein and calories until you can get a meal.
    • If you forgot to bring anything to eat, ask the staff where you have had blood drawn. They may keep cookies or crackers around for just this purpose.
  2. Some tests can be finished within 24 hours while others can take a week or more if the blood must be shipped to a special laboratory. Talk with your doctor about the process used to deliver the results of the blood test. In some cases the office will not notify you if the results are all within normal limits. If the blood is sent off, also ask how long it will be before the office gets the results from the laboratory.
    • Ask to be notified, even if the results are normal. This will ensure that your results don’t "fall through the cracks" and you aren’t notified if the results are not normal.
    • Call the doctor’s office 36 to 48 hours after the results should have arrived if you are not notified.
    • Ask your doctor’s office if they use an online notification system. You may be given a website to register through so your results can be delivered digitally to you.
  3. The most common side effect of having blood drawn is a bruise, or hematoma, at the site where the needle went in. The bruise can show up immediately or within 24 hours after the blood was drawn. Some of the factors that contribute to the formation of a hematoma include blood leaking out of the opening when a needle goes through a vein, which leaks into the surrounding tissue. They can also be caused by bleeding disorders or anticoagulant medications, which increases the risk that a bruise or hematoma will occur where the blood is drawn. [33]
    • If the bruise is painful, wrap some ice in a cloth and hold it against the area for about 10 minutes. [34]
    • To help reduce the chance that you'll get a bruise, hold firm pressure on the gauze for at least 2 minutes after your blood is drawn. [35]
    • Hemophilia is the most well-known bleeding disorder, but it is also fairly rare. It comes in two forms - A & B. [36]
    • Von Willebrand disease (VWD) is the most common bleeding disorder, and affects how your blood clots. [37]
    • Patients should let their doctor and phlebotomist know they have a bleeding disorder when they get their blood drawn.
  4. There are certain situations that can lead to inaccurate results on your blood tests. Prolonged tourniquet application can lead to a pooling of blood in the arm or extremity where the blood was being drawn. This increases the concentration of blood and increases the potential for false positive or negative results on the blood tests. [38]
    • The tourniquet should be in place for no longer than one minute to prevent pooling, also called hemoconcentration.
    • If longer than a minute is needed to locate a choice vein, then the tourniquet should be released and reapplied after two minutes and only immediately before the needle is inserted.
  5. Hemolysis is a problem with the blood sample and not a complication which you experience. Hemolysis happens when the red blood cells rupture and other components spill into the blood serum. [39] Hemolyzed blood is not acceptable for testing and another blood sample will have to be drawn. [40] Hemolysis is more likely to occur when: [41]
    • The tube is mixed vigorously after being removed from the needle.
    • Drawing blood from a vein near a hematoma.
    • Using a smaller needle which damages the cells as they are drawn into the tube.
    • Excessive fist clenching during the blood draw.
    • Leaving the tourniquet on for more than one minute.
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  • Question
    What is the best time to get your blood test done?
    Chris M. Matsko, MD
    Family Medicine Physician
    Dr. Chris M. Matsko is a retired physician based in Pittsburgh, Pennsylvania. With over 25 years of medical research experience, Dr. Matsko was awarded the Pittsburgh Cornell University Leadership Award for Excellence. He holds a BS in Nutritional Science from Cornell University and an MD from the Temple University School of Medicine in 2007. Dr. Matsko earned a Research Writing Certification from the American Medical Writers Association (AMWA) in 2016 and a Medical Writing & Editing Certification from the University of Chicago in 2017.
    Chris M. Matsko, MD
    Family Medicine Physician
    Expert Answer
    Usually the morning is good, especially if you are required to fast beforehand.
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  • Question
    Does it hurt as much as getting a shot?
    Chris M. Matsko, MD
    Family Medicine Physician
    Dr. Chris M. Matsko is a retired physician based in Pittsburgh, Pennsylvania. With over 25 years of medical research experience, Dr. Matsko was awarded the Pittsburgh Cornell University Leadership Award for Excellence. He holds a BS in Nutritional Science from Cornell University and an MD from the Temple University School of Medicine in 2007. Dr. Matsko earned a Research Writing Certification from the American Medical Writers Association (AMWA) in 2016 and a Medical Writing & Editing Certification from the University of Chicago in 2017.
    Chris M. Matsko, MD
    Family Medicine Physician
    Expert Answer
    It is comparable to getting a shot, but the stick (depending on the skill of the phlebotomist) might be less.
    Thanks! We're glad this was helpful.
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    Not Helpful 2 Helpful 19
  • Question
    How do I check for Hepatitis C if my veins are collapsed?
    Chris M. Matsko, MD
    Family Medicine Physician
    Dr. Chris M. Matsko is a retired physician based in Pittsburgh, Pennsylvania. With over 25 years of medical research experience, Dr. Matsko was awarded the Pittsburgh Cornell University Leadership Award for Excellence. He holds a BS in Nutritional Science from Cornell University and an MD from the Temple University School of Medicine in 2007. Dr. Matsko earned a Research Writing Certification from the American Medical Writers Association (AMWA) in 2016 and a Medical Writing & Editing Certification from the University of Chicago in 2017.
    Chris M. Matsko, MD
    Family Medicine Physician
    Expert Answer
    You will need to find a phlebotomist that has experience with people that have collapsed veins.
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      References

      1. ↑ https://www.nhlbi.nih.gov/health/health-topics/topics/bdt
      2. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      3. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      4. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      5. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      6. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      7. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      8. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      9. ↑ https://labtestsonline.org/understanding/features/test-prep/
      1. ↑ https://medlineplus.gov/lab-tests/how-to-prepare-for-a-lab-test/
      2. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      3. ↑ https://www.bls.gov/ooh/healthcare/phlebotomists.htm
      4. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      5. ↑ https://www.aaaai.org/conditions-and-treatments/allergies/latex-allergy.aspx
      6. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      7. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      8. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      9. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      10. ↑ https://journals.sagepub.com/doi/full/10.1177/2377960818759442
      11. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5665840/
      12. ↑ https://www.drugs.com/emla.html
      13. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      14. ↑ https://kidshealth.org/en/parents/labtest4.html
      15. ↑ https://www.youtube.com/watch?v=bqSt7wLxCDQ
      16. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      17. ↑ https://kidshealth.org/en/parents/labtest4.html
      18. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      19. ↑ https://www.health.harvard.edu/mind-and-mood/relaxation-techniques-breath-control-helps-quell-errant-stress-response
      20. ↑ https://www.mentalhealthsf.org/six-simple-habits-that-defeat-anxiety/
      21. ↑ https://screening.mhanational.org/content/my-brain-is-playing-tricks-on-me/
      22. ↑ https://www.helpguide.org/articles/anxiety/social-anxiety-disorder.htm
      23. ↑ https://selfcontrol.psych.lsa.umich.edu/wp-content/uploads/2014/01/KrossJ_Pers_Soc_Psychol2014Self-talk_as_a_regulatory_mechanism_How_you_do_it_matters.pdf
      24. ↑ https://my.clevelandclinic.org/health/diseases/16788-blood-clotting-disorders-hypercoagulable-states
      25. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      26. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.
      27. ↑ https://my.clevelandclinic.org/health/diseases/14083-hemophilia
      28. ↑ https://www.hematology.org/Patients/Bleeding.aspx
      29. ↑ https://www.labce.com/spg263726_avoid_prolonged_tourniquet_time.aspx
      30. ↑ https://medlineplus.gov/ency/article/002372.htm
      31. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6425048/
      32. ↑ https://eclinpath.com/hematology/sample-collection-heme/
      33. ↑ Matt Garcia. Phlebotomist. Expert Interview. 9 November 2020.

      About This Article

      Article Summary X

      If you need to get a blood test, ask your doctor if they have special instructions. For example, you may need to fast before some tests to get accurate results. You should also let them know if you’re taking any medications or supplements that might affect your test. Before getting your blood drawn, drink plenty of fluids to help your blood flow better. Additionally, you can put a warm compress on the vein where the blood will be drawn to improve your circulation. Make sure to tell your phlebotomist if you have any concerns, such as an allergy to latex. For more tips from our Medical co-author, including how to prepare mentally for a blood test, keep reading!

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