Also Known As
Mononucleosis spot test
Mononuclear heterophil test
Heterophil antibody test
Mono test
Formal Name
Heterophil antibody titre
This article was last reviewed on
This article waslast modified on 16 November 2018.
At a Glance
Why Get Tested?

To get screened for infectious mononucleosis (glandular fever). 

When To Get Tested?

If you have symptoms of mononucleosis, including fever, sore throat, swollen glands, and fatigue. (The monospot test is not useful to detect EBV in children.)

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?


On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

The Monospot test detects heterophil antibodies. It detects a reaction with horse red blood cells. A similar test, the Paul-Bunnell test, detects a reaction with sheep red blood cells. The antibodies are made in response to an infection by Epstein-Barr virus (EBV). EBV causes infectious mononucleosis (glandular fever), a self-limiting disease.

Mononucleosis is characterised by the presence of atypical white blood cells (atypical lymphocytes) in an infected person. Patients have these symptoms: fever, sore throat, swollen glands, and fatigue. About 70%–80% of patients with infectious mononucleosis produce these heterophil antibodies, which are not specific for EBV infection but are a good predictor of EBV infection.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    The Monospot test is used to determine whether you have infectious mononucleosis. This test is rapid and easy to perform, but it is not 100% specific. More testing may be needed to confirm that the disease is mononucleosis and not another illness.

  • When is it requested?

    The Monospot test is requested if your doctor suspects that you have infectious mononucleosis, which causes fever, headache, swollen glands, tiredness, and malaise. Your healthcare professional may detect that you have an enlarged spleen or liver.

    The test will not be positive until you have been infected for about two weeks. Other tests may need to be requested if the heterophil antibodies are negative, but your doctor still suspects mononucleosis as the cause of your symptoms.

    Other blood tests that are more specific to the EBV can be used to find early infection or to confirm mononucleosis. These tests include the IgM and IgG antibodies to the viral capsid antigen (VCA), which can be found early in the disease. VCA IgM is only present in the few weeks after infection, but the IgG antibodies can also be found later, during the patient's recovery. Antibodies to Epstein-Barr virus Nuclear Antigen (EBNA) may also be tested for to gain a more accurate indication of recent or previous EBV infection.

  • What does the test result mean?

    A positive result in the Monospot test, together with symptoms of mononucleosis, are the basis for a diagnosis of infectious mononucleosis. In addition to a positive reaction on the Monospot test, an infected person has a higher white blood cell count, with a higher than usual number of atypical lymphocytes. Heterophil antibodies decline after the fourth week of illness, and the Monospot test will become negative as the infection resolves.

    A negative test result means that a person may not have mononucleosis or that it is too early in the illness to detect the antibodies. The test may need to be repeated if symptoms remain. Infants and young children do not make heterophil antibodies when infected with EBV, so more specific viral tests must be used to make the diagnosis.

    Interpretation of Specific EBV Test results

    EBV IgM antibody EBV IgG antibody EBNA antibody Interpretation
    Positive Negative Negative Recent EBV infection
    Positive Positive Negative Recent EBV infection
    Negative Positive Positive Previous EBV infection
  • Is there anything else I should know?

    In young adults, an effective laboratory diagnosis can be made on a single blood sample during the acute phase of the disease with a Monospot test. By requesting the more extensive battery of EBV blood tests, the healthcare professional will be able to learn whether a person is susceptible to EBV, has had a recent infection, has had EBV infection in the past, or has a reactivated EBV infection.

    When the Monospot test is negative, a combination of EBV antibody tests for IgM and IgG to the viral capsid antigen, IgM to the early antigen, and IgG antibody to the nuclear antigen may be requested, as well as antibody tests for cytomegalovirus (CMV) or Toxoplasma gondii.

  • How serious is infectious mononucleosis?

    The symptoms of the disease usually resolve without treatment in one to four months. Sometimes, your spleen or liver may enlarge, and you may have to limit your activity until these organs return to normal size. Heart problems or involvement of the central nervous system occur only rarely. Infectious mononucleosis may cause severe liver failure in males with a very rare special XLP gene. In this case, mononucleosis can be fatal.

  • Is mononucleosis really a "kissing disease"?

    The spread of EBV requires intimate contact with saliva (found in the mouth) of an infected person. Kissing can transmit infection, but saliva on toys, drink containers or hands can also transmit the virus. Transmission through the air or blood does not normally occur. The incubation period, the time from infection to appearance of symptoms, ranges from 4 to 6 weeks.

    People who have infectious mononucleosis may be able to spread the infection to others for a period of weeks. Many healthy people can carry and spread the virus intermittently for life, and testing them for the virus is not practicable. For this reason, it is almost impossible to prevent the spreading of the virus.

  • Does Epstein-Barr virus cause chronic fatigue syndrome?

    There is no laboratory evidence indicating that EBV infection causes chronic fatigue. For more information, visit the Centers for Disease Control and Prevention’s website.

  • Can I get infectious mononucleosis more than once?

    Although the symptoms of infectious mononucleosis usually go away in 1 or 2 months, EBV remains inactive in a few cells in the body for the rest of the person's life. Periodically, the virus can reactivate, and it is commonly found in the saliva of infected persons, particularly if they are immunosuppressed. This reactivation usually occurs without symptoms of illness.

  • Can EBV cause other serious illnesses?

    EBV has been linked to certain cancers, such as Burkitt’s lymphoma, Hodgkin’s disease, nasopharyngeal carcinoma, and AIDS-related lymphoma, and continues to be studied for possible linkages to these and other cancers. All these diseases are rare.