The essentials

Low lymphocytes (lymphopenia) means fewer of the white blood cells that fight viruses than your lab expects. A mild, isolated low count is common and often follows a recent virus, a steroid medicine or physical stress. What matters is the absolute count, whether it stays low on a repeat test, and whether frequent infections or other abnormal counts come with it.

What does low lymphocytes mean on a blood test?

Lymphocytes are counted in a complete blood count with differential[1][6]. Here is a fictitious report in US format.

Fictitious example of a lab report (United States format)
TestResultReference rangeFlag
WBC (white blood cells)5.2 x10³/µL4.0-11.0 x10³/µL-
Neutrophils, absolute3.6 x10³/µL1.8-7.7 x10³/µL-
Lymphocytes, absolute0.8 x10³/µL1.0-4.8 x10³/µLL
Lymphocytes %15 %20-40 %L
  1. Absolute count: 0.8 x10³/µL means 800 lymphocytes per microliter, the number doctors rely on.
  2. Percentage: the share of all white cells that are lymphocytes, usually 20% to 40%[5]. It can drop only because neutrophils rose, so a low percentage with a normal absolute count often means little.
  3. Flag L: below your laboratory's range. Other white cells are normal here, so the low value is isolated.

Have an L next to your lymphocytes? BloodSense reads your whole blood count with you, line by line, and helps you list the questions to bring to your doctor.

Explain my blood count

Cutoffs differ between sources. The National Heart, Lung, and Blood Institute (NHLBI) uses fewer than 1,500 cells/µL in adults and fewer than 2,000 cells/µL in children age 6 and younger[1]. Cleveland Clinic gives an adult range of 1,000 to 4,800 cells/µL and calls lymphopenia below 1,000[5]. In a large US survey of adults, 20.1% had a count of 1,500/µL or less and 3.0% had 1,000/µL or less[8]. For the general guide, see the lymphocytes blood test.

When should I worry about low lymphocytes?

A low count alone may cause no symptoms and is often found on a routine checkup[3].

When to see a doctor

  • Emergency: call 911 for high fever with confusion, or trouble breathing[12], especially if you take chemotherapy or other treatment that weakens the immune system.
  • Within 24 to 48 hours for fever or chills, a cough, pain when urinating or red, swollen skin[12], or if your report also shows low red cells or platelets.
  • At your next appointment if you feel well and only the lymphocytes are slightly low. Ask whether and when to repeat the test.

What causes low lymphocytes?

Lymphopenia can be inherited or acquired[2]. Viral infections (including HIV) and undernutrition are the most common causes[4].

  • Common A recent viral infection such as the flu, COVID-19 or viral hepatitis. The drop is usually temporary[2][4].
  • Common Corticosteroids such as prednisone[4]. They most likely shift lymphocytes out of the blood into other tissues for a while, rather than destroying them[10].
  • Common Physical stress: severe illness, major surgery or fasting[2][4].
  • Common Drinking too much alcohol and poor nutrition, meaning a diet without enough protein or other nutrients[2].
  • Possible Cancer treatment (chemotherapy, radiation) and blood or bone marrow transplant[2][4].
  • Possible Autoimmune diseases: lupus, rheumatoid arthritis and Sjögren's disease[2].
  • Possible Longer-lasting infections: HIV, tuberculosis, pneumonia, sepsis and malaria[2].
  • Rare Blood diseases: Hodgkin lymphoma and aplastic anemia[2].
  • Rare Inherited immune disorders, usually found in childhood: severe combined immunodeficiency (SCID), 22q11.2 deletion (DiGeorge) syndrome, common variable immunodeficiency, Wiskott-Aldrich syndrome and ataxia telangiectasia[2].

Can a low lymphocyte count be temporary or a false alarm?

Yes, often. A result outside the range does not always mean a condition that needs treatment: diet, activity, medicines and hydration can change blood counts[7]. Check these points:

  • Was the test taken during or just after a cold, the flu or COVID-19?
  • Did you take a steroid (tablet, injection or a short course) in the days before?
  • Was it drawn after surgery or fasting?
  • Is only the percentage low, with a normal absolute count? Compare with your neutrophil count.
  • Is it one result, or the same low value on several tests weeks apart?

Some tests need to be repeated before a conclusion is drawn[1].

What symptoms can come with low lymphocytes?

Signs usually come from the cause or from infections: infections that keep coming back or last long, unusual infections, swollen lymph nodes, an enlarged spleen, mouth sores, and poor growth in children[3]. A Danish study of 98,344 people linked a count below 1,100/µL to about 40% more hospital stays for infection, a link rather than proof of cause[9].

What tests will my doctor order next?

The next step depends on how low the count is, how long it lasts and what else is abnormal. Options[1][4]:

  • A repeat complete blood count to confirm the drop and check the other white blood cells.
  • Flow cytometry, which counts T cells, B cells and natural killer cells.
  • Immunoglobulin (antibody) levels.
  • Tests for infections such as HIV, tuberculosis or COVID-19. The CDC recommends that everyone aged 13 to 64 be tested for HIV at least once[11]; see HIV test results.
  • Rarely, a bone marrow or lymph node exam.

Questions to ask your doctor

  1. Is my absolute lymphocyte count low, or only the percentage?
  2. Could a recent infection, a steroid or another medicine explain it?
  3. Are my other blood counts normal?
  4. When should I repeat the test, and do I need an HIV test or other checks?

Frequently asked questions

Is lymphopenia a sign of cancer?

Rarely. Infections, medicines and nutrition are far more frequent causes[5]. Hodgkin lymphoma is one of the less common causes[2]; a count that stays low with other symptoms is checked further.

How can I raise my lymphocyte count?

Treatment targets the cause, such as an infection or a medicine. Mild cases with no symptoms do not need treatment[5]. Do not stop a steroid or other medicine on your own.

What does low lymphocytes with high neutrophils mean?

It often reflects stress on the body, an infection or a steroid: steroids raise neutrophils and lower lymphocytes together[10].

References

  1. National Heart, Lung, and Blood Institute. Lymphopenia: diagnosis. nhlbi.nih.gov (accessed October 29, 2026)
  2. National Heart, Lung, and Blood Institute. Lymphopenia: causes and risk factors. nhlbi.nih.gov (accessed October 29, 2026)
  3. National Heart, Lung, and Blood Institute. Lymphopenia: symptoms. nhlbi.nih.gov (accessed October 29, 2026)
  4. Merck Manual Consumer Version. Lymphocytopenia. merckmanuals.com (accessed October 29, 2026)
  5. Cleveland Clinic. Lymphopenia: symptoms, causes and treatment. my.clevelandclinic.org (accessed October 29, 2026)
  6. MedlinePlus Lab Tests. Blood differential. medlineplus.gov (accessed October 29, 2026)
  7. MedlinePlus Lab Tests. Complete blood count (CBC). medlineplus.gov (accessed October 29, 2026)
  8. Zidar DA, Al-Kindi SG, Liu Y, et al. Association of lymphopenia with risk of mortality among adults in the US general population. JAMA Netw Open. 2019;2(12):e1916526. doi:10.1001/jamanetworkopen.2019.16526 (accessed October 29, 2026)
  9. Warny M, Helby J, Nordestgaard BG, Birgens H, Bojesen SE. Lymphopenia and risk of infection and infection-related death in 98,344 individuals from a prospective Danish population-based study. PLoS Med. 2018;15(11):e1002685. doi:10.1371/journal.pmed.1002685 (accessed October 29, 2026)
  10. Fauci AS, Dale DC, Balow JE. Glucocorticosteroid therapy: mechanisms of action and clinical considerations. Ann Intern Med. 1976;84(3):304-15. doi:10.7326/0003-4819-84-3-304 (accessed October 29, 2026)
  11. Centers for Disease Control and Prevention. Getting tested for HIV. cdc.gov (accessed October 29, 2026)
  12. The Blood Project. Understanding lymphocytopenia. thebloodproject.com (accessed October 29, 2026)
  13. Medicare.gov. Diagnostic laboratory tests. medicare.gov (accessed October 29, 2026)

This article is general health information. It does not replace a medical examination, diagnosis or treatment. If you have a high fever, confusion or trouble breathing, seek care without waiting.