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Low Monocytes? 6 Ways to Improve Immune Function

Written by Joe Cohen, BS | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Joe Cohen, BS | Last updated:

Monocytes are the largest of all white blood cells and play an important role in the defense against germs and in inflammation. What do low levels mean? What factors can increase them? Learn more here.

Low Levels of Monocytes (Monocytopenia)

In monocytopenia, the number of monocytes circulating in the blood is decreased to less than 0.2×109/L in adults. Monocytopenia itself does not appear to produce symptoms, and patients usually only show symptoms related to an associated condition. Such symptoms may include fatigue and fever [1, 2].

Conditions Associated with Monocytopenia

  • Aplastic anemia [3]
  • Leukemia (hairy-cell leukemia, chronic lymphocytic leukemia) [4]
  • Chemotherapy [5]
  • MonoMAC syndrome (monocytopenia and Mycobacterium Avium Complex syndrome) [6]
  • Severe burn injuries [7]
  • Rheumatoid arthritis [8]
  • Systemic lupus erythematosus [9]
  • HIV infection [10]
  • Vitamin B12 deficiency [11]
  • Corticosteroid therapy (transient monocytopenia) [12]
  • Administration of INF-alpha and TNF-alpha [13]
  • Radiation therapy [14]

Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.

Autoimmune diseases, HIV, burns, and many other conditions and therapies are associated with reduced monocyte count; symptoms depend on the underlying cause.

How Is Monocytopenia Linked to Health?

1) Cardiovascular Disease

Out of all white blood cells, monocyte count has the strongest relationship with rates of cardiovascular disease in people with no symptoms. Lower levels of monocytes are associated with lower cardiovascular risk [15].

2) Susceptibility to Infection

Monocytes are involved in the immune response to infection; thus, it’s unsurprising that low monocyte counts are linked to increased rates of infection. Monocytopenia is more specifically associated with the MonoMAC syndrome: increased susceptibility to mycobacterial, fungal, and human papillomavirus (HPV) infections [6, 1].

3) Blood Disorders

Monocytopenia is associated with blood disorders such as myelodysplasia, acute myelogenous leukemia, chronic myelomonocytic leukemia, and lymphomas. If you are worried about low monocyte levels and your risk of these blood disorders, talk to your doctor about additional available tests [16].

4) Cervical Cancer

Patients with primary immunodeficiency have low monocyte levels and are susceptible to severe, persistent human papillomavirus (HPV) infections that may cause cervical cancer. If you have concerns, talk to your doctor about strategies for cervical cancer prevention, especially if you have not been vaccinated against HPV [17, 18].

Low monocytes (monocytopenia) may lower your risk of heart disease but make you more prone to infections and blood disorders.

Other Factors That Decrease Monocytes

Certain hormones and medications have been associated with decreased monocyte levels.

1) Cortisol and Glucocorticoids

As administered by a doctor, a single dose of cortisol decreases monocytes by 90% at 4 to 6 hours after treatment. This reduction persisted for about 24 hours. Subsequently, monocyte levels return to normal 24 to 72 hours after treatment [19].

2) Estrogen and Progesterone

According to one study, estrogen (and possibly also progesterone) decreases monocyte count by preventing monocytes from reproducing. This mechanism could explain why cell-mediated immunity appears to drop during pregnancy [20].

3) Infliximab

Infliximab is an immune-suppressing drug prescribed for the treatment of inflammatory diseases such as Crohn’s, ulcerative colitis, and rheumatoid arthritis [21, 22, 23].

Infliximab kills monocytes, which may help reduce inflammation in patients with chronic inflammatory diseases [24].

Estrogen, progesterone, cortisol, and new immune-suppressing drugs lower inflammation and reduce monocytes.

Ways to Increase Monocyte Levels

1) Healthiest ways to strengthen your immune system

Remember, low monocyte levels are usually a sign of a weak immune system. Your first line of defense and the first strategy to boost your immune system is to live a healthy lifestyle. The following good-health guidelines are still the most recommended strategies for improving your immune health [25]:

  • Don’t smoke.
  • Eat a diet high in fruits and vegetables.
  • Exercise regularly.
  • Maintain a healthy weight.
  • Get a good night’s sleep.
  • Take steps to avoid infection, such as frequently washing your hands and cooking meats thoroughly.
  • Minimize stress.

2) Vitamin B12

In a study of rats with protein deficiency, vitamin B12 supplementation resulted in increased white blood cell count, including monocytes. However, supplementation with vitamin B12 did not change white blood cell count in rats that ate normal amounts of protein [26].

Because this was an animal study with very particular parameters, it is unclear whether or how much these results apply to humans.

3) Vitamin C

In one study, people with low plasma vitamin C had less effective monocytes than those with normal vitamin C levels; furthermore, the first group’s monocytes normalized after they were given vitamin C supplements. In a cell study, monocytes exposed to vitamin C survived at a higher rate than those without vitamin C [27, 28].

4) Vitamin D

In cell studies, calcitriol (vitamin D) stimulates the growth of human monocytes. Researchers believe that vitamin D is important for monocyte function [29].

5) Garlic

In one study, rats fed garlic had significantly more monocytes, neutrophils, and lymphocytes than rats not fed with garlic. In cell studies, garlic extracts have also been found to increase the anti-inflammatory signals (IL-10) produced by monocytes [30, 31].

6) Reduce Excessive Alcohol Drinking

Alcohol consumption may contribute to “leaky gut,” in which lipopolysaccharides (LPS) from gut bacteria cross into the bloodstream and cause inflammation. Chronic alcohol consumption can raise monocytes and inflammatory proteins, contributing to widespread inflammation. Prolonged alcohol intake also increases TNF-alpha production by monocytes [32, 33, 34].

The best way to increase your monocyte count is to boost your immune health by living a healthy lifestyle: quit smoking, minimize stress, exercise regularly, eat lots of fruits/vegetables, get a good night’s sleep, and avoid infections by washing your hands frequently. Very early research suggests that garlic and supplementing with vitamin C, D, and B12 may be beneficial.

Remember these are general recommendations for improving your immune health that may increase your monocyte count. The most important thing you can do is to follow the advice of your doctor.


A low number of monocytes (monocytopenia) can be caused by anything that decreases the overall white blood cell count, such as bloodstream infection, chemotherapy, or a bone marrow disorder. It’s important to speak with your doctor about what this means and what recommendations he has for you based on your results. Having a low number of monocytes is usually a sign of having a weak immune system. In addition to any of your doctor’s recommendations, the best way to boost your immune health is to maintain a healthy lifestyle: quit smoking, minimize stress, exercise regularly, get a good night’s sleep, and avoid infections by washing your hands frequently.

Learn More

Want to learn more about monocytes and how they work? Check out:

About the Author

Joe Cohen, BS

Joe Cohen, BS

Joe Cohen flipped the script on conventional and alternative medicine…and it worked. Growing up, he suffered from inflammation, brain fog, fatigue, digestive problems, insomnia, anxiety, and other issues that were poorly understood in traditional healthcare. Frustrated by the lack of good information and tools, Joe decided to embark on a learning journey to decode his DNA and track his biomarkers in search of better health. Through this personalized approach, he discovered his genetic weaknesses and was able to optimize his health 10X better than he ever thought was possible. Based on his own health success, he went on to found SelfDecode, the world’s first direct-to-consumer DNA analyzer & precision health tool that utilizes AI-driven polygenic risk scoring to produce accurate insights and health recommendations. Today, SelfDecode has helped over 100,000 people understand how to get healthier using their DNA and labs.
Joe is a thriving entrepreneur, with a mission of empowering people to take advantage of the precision health revolution and uncover insights from their DNA and biomarkers so that we can all feel great all of the time.


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