What Is the Mono Blood Test?

What to Expect When Undergoing This Test

The Epstein-Barr virus (EBV) test is a screening tool to check for antibodies in a person’s blood. Epstein-Barr virus is a common cause of mononucleosis (mono); therefore, this test could be used to help diagnose the infection.

Woman having blood drawn by phlebotomist

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Purpose of the Test

A doctor can use the EBV blood test when a patient has signs of mono, which can show up anywhere between four to six weeks after the initial infection.

Symptoms may include:

Your doctor may also look for an enlarged spleen or a swollen liver.

Diagnosis of Mono

Mono is typically diagnosed based on symptoms, not bloodwork. Additional blood markers for people with mono may include elevated or atypical lymphocytes (a type of white blood cell), low neutrophils (another type of white blood cell), low platelets (cells involved in clotting), and abnormal liver function tests.

The Epstein-Barr virus test looks for antibodies produced by the body when fighting an EBV infection. These particular antibodies are of interest because EBV is a common cause of mono. Someone who has never been infected with EBV should not have EBV antibodies.

The EBV antibody test results may present as negative if the person tested too early. It takes time for the body to produce antibodies to an infection. The immune system may not have had sufficient time to respond to EBV if mono was just recently contracted. It may also be negative if mono is caused by a different virus.

It may be necessary to take the test multiple times to give the antibodies time to develop. Your doctor may ask you to come back for a retest after 10 to 14 days.

Mono can also be detected through a test called the Monospot test, or heterophile test. This test is also a blood test, but instead of EBV antibodies, it looks for heterophile antibodies, which can also be seen in conditions other than mono. The Monospot test can detect the antibodies for two to nine weeks after infection.

In clinical practice, many doctors start with a Monospot test as it is relatively fast and inexpensive. It supports a diagnosis of mono but is not a confirmation of EBV infection. If it is negative but the patient has typical symptoms of mono, they proceed to specific EBV testing.

Risks and Contraindications

The EBV test is a blood test. The risks of taking a blood test at a reputable facility are minimal. However, some possible risks include discomfort from the needle insertion and possible bruising at the blood draw site.

Some people experience temporary redness and swelling. In rare cases, an infection can occur where blood was drawn. If you’re anxious about having blood taken, you may feel lightheaded or faint during the test.

Before the Test

Once the doctor decides to send you to get an EBV test, they might ask if you are taking any medications to make sure you aren’t on something that may affect the test results. Your doctor may also ask if you have had any complications with previous blood tests, such as fainting, so they can be prepared.

Timing

Blood tests like the EBV test typically only take five to 10 minutes. However, you may want to arrive early at the lab if there are forms to fill out, such as a brief medical history or consent form to have your blood drawn. 

A blood test may take longer if the technician taking the blood has difficulty finding the proper vein to draw the blood from. Typically the results for the EBV test will be available within three days.

Location

You may be able to get an EBV antibody test right at your doctor’s office. However, if they cannot perform the test at the office, you’ll be sent to a lab with technicians who specialize in drawing blood (phlebotomists).

What to Wear

You can wear normal clothing to an EBV test and will not need to bring a change of clothes. Loose-fitting shirts or layers that allow quick access to the veins on your arms will make the test easier to perform.

Food and Drink

Fasting is not required before an EBV antibody test. You can eat and drink as usual both before and after the test. However, if you are having other tests drawn at the same time, check for restrictions related to those tests.

Cost and Health Insurance

Like most blood tests recommended by doctors, health insurance should cover an EBV test, depending on your insurance plan. However, this may not be the case for all carriers, so you can call your insurance provider before getting the test to determine what you’ll be responsible for paying.

What to Bring 

When going to the EBV test, make sure to bring a valid insurance card and personal identification. Also, make sure to bring any forms that the doctor may have provided to you when ordering the test.

During the Test 

When you go to get an EBV antibody test, a medical technician trained in phlebotomy will bring you into a private room with a chair and an armrest.

Pre-Test

The medical tech should double-check your name and the labels on the tubes that contain the blood to verify that you’re the right person and receiving the correct test. They may review some details on your medical history or ask you some background questions as part of the check-in process before taking your blood.

Throughout the Test

Next, the technician should place a tourniquet on your arm to help control blood flow to the veins. As they select a vein to draw from, they might ask you to make a fist. The technician will clean and sanitize the area to prevent infection before inserting a needle.

Once the needle has been inserted, they will ask you to release your fist. You may feel nothing during this procedure, or you may feel a slight pinch. The whole process should take no longer than 10 minutes. Some people choose to look away if they feel uneasy about having blood drawn.

Post-Test

After filling up the designated tubes with blood samples, the technician may apply an adhesive bandage or gauze to the puncture site on your arm. You should then be allowed to leave.

After the Test

You may have some soreness or bruising after a blood test. Applying ice can help with this, and it should go away within a couple of days. Unless you notice signs of an infection (like a fever), there should be no need to contact your doctor.

Interpreting Results

Your EBV antibody test results should be available within three days. The results can show if you are susceptible to mono, meaning you don’t have the antibodies. If you are currently infected with EBV or have been infected with it in the past, you should test positive for antibodies.

Different antibody tests may be done, so you may see some or all of the results for:

  • Viral capsid antigen (VCA): Anti-VCA IgM antibodies appear early in infection, while anti-VCA IgG antibodies are highest two to four weeks after infection, then can persist indefinitely.
  • Early antigen: Antibodies to this antigen are usually the sign of an active infection, but can be seen in healthy people as well.
  • EBV nuclear antigen (EBNA): These antibodies are seen two to four months after symptoms develop and can persist for life.

Your doctor will need to use their skill in interpreting these tests in light of your symptoms and where you might be in the course of an EBV infection.

For most people, the symptoms of mono last about two to four weeks, but they can last six months or longer in some cases. Your doctor will be able to prescribe medication to help you recover.

Follow-Up

If your test is negative but you have symptoms of mono, you can request a follow-up test with your doctor.

Summary

Mononucleosis is usually diagnosed based on symptoms, but sometimes a healthcare professional will order an Epstein-Barr virus blood test. This virus is a common cause of mono. This is performed as a blood draw from a vein. A positive result means you have a current or past infection with EBV. A negative result may be seen early in the infection.

A Word From Verywell

While waiting for your test results, you can manage mono symptoms by staying hydrated, getting plenty of rest, and taking over-the-counter medication for pain. Infectious mononucleosis takes time to go away, but it’s a common and treatable condition. With your doctor’s help, you should be back to health in no time.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. University of Michigan Health. Mononucleosis tests. Updated September 23, 2020.

  4. Centers for Disease Control and Prevention. Epstein-Barr virus laboratory testing. Updated September 28, 2020.

  5. National Heart, Lung, and Blood Institute. Blood tests.

  6. Northwestern Office for Research, Institutional Review Board (IRB) Office. Blood draw.