Immunodeficiency disorders prevent your body from fighting infections and diseases. This type of disorder makes it easier for you to catch viruses and bacterial infections.

Key points

  1. Immunodeficiency disorders disrupt your body’s ability to defend itself against bacteria, viruses, and parasites.
  2. There are two types of immunodeficiency disorders: those you are born with (primary), and those that are acquired (secondary).
  3. Anything that weakens your immune system can lead to a secondary immunodeficiency disorder.
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Immunodeficiency disorders are either congenital or acquired. A congenital, or primary, disorder is one you were born with. An acquired, or secondary, disorder is one you get later in life. Acquired disorders are more common than congenital disorders.

Your immune system includes the following organs:

These organs process and release lymphocytes. These are white blood cells classified as B cells and T cells. B and T cells fight invaders called antigens. B cells release antibodies specific to the disease your body detects. Certain T cells destroy foreign or atypical cells.

Examples of antigens that your B and T cells might need to fight off include:

  • bacteria
  • viruses
  • cancer cells
  • parasites

An immunodeficiency disorder disrupts your body’s ability to defend itself against these antigens.

What is a weak immune system?

If you have a weaker immune system, you’re immunocompromised. This means your body can’t fight off infections or viruses as well as people who are not immunocompromised.

While a weaker immune system is typically caused by certain diseases, malnutrition, and certain genetic disorders, it can also temporarily be caused by medications such as anticancer drugs and radiation therapy.

Your immune system can also be temporarily weakened by a stem cell or organ transplant.

There are hundreds of forms of immunodeficiency disorders. Each disorder has unique symptoms that can be frequent or chronic. However, there are a few warning signs that something may be going on with your immune system.

Individuals with immunodeficiency disorders tend to have frequent infections — one round after another — of certain conditions, such as:

Individuals with immunodeficiency disorders may also develop chronic abdominal pain, and they may even lose weight over time.

If you find that you get sick easily and have a hard time shaking off viruses and other infections, your doctor might test you for an immunodeficiency disorder.

An immune deficiency disease or disorder occurs when the immune system is not working as expected. If you’re born with a deficiency from a genetic cause, it’s called primary immunodeficiency disease. There are more than 200 primary immunodeficiency disorders.

Examples of primary immunodeficiency disorders include:

  • common variable immunodeficiency (CVID)
  • severe combined immunodeficiency (SCID), which is also known as alymphocytosis
  • chronic granulomatous disease (CGD)

Secondary immunodeficiency disorders happen when an outside source like a chemical or infection weakens your body. The following can cause a secondary immunodeficiency disorder:

Examples of secondary immunodeficiency disorders include:

Primary immunodeficiency disorders are most commonly caused by inherited gene mutations.

Secondary immunodeficiency disorders can be caused by a variety of things, including:

  • chronic conditions (like diabetes or cancer)
  • drugs
  • radiation therapy (this is rare)
  • long-term hospitalization
  • insufficient nutrition

Risk factors

People who have a family history of primary immunodeficiency disorders have a higher risk for developing primary disorders themselves.

Anything that weakens your immune system can lead to a secondary immunodeficiency disorder. For example, exposure to body fluids infected with HIV or organ removal and replacement can both be causes.

Aging can also weaken your immune system. As you age, some of the organs that produce or process white blood cells shrink and become less efficient.

Proteins are important for your immunity. Not enough protein in your diet can weaken your immune system.

Your body also produces proteins when you sleep that help your body fight infection. For this reason, lack of sleep can reduce your immune defenses.

Cancers and chemotherapy drugs can also reduce your immunity.

If your doctor thinks you might have an immunodeficiency disorder, they will want to:

Your doctor may also perform a skin test, which is usually performed when a T-cell abnormality is suspected.

During a skin test, a small number of proteins from common infectious organisms (like yeast) are injected right under the skin. If there’s not a reaction (swelling or redness) within 2 days, that can be a sign of an immunodeficiency disorder from a T-cell abnormality.

Biopsies of the lymph nodes or bone marrow may also be performed to help your doctor narrow down which disorder may be causing your symptoms.

Genetic testing, usually via a blood test, to determine if there are any gene mutations that are causing your immunodeficiency disorder may also be ordered.

Treating immunodeficiency disorders typically revolves around:

  • preventing infections when possible
  • treating infections when they occur
  • strengthening parts of the immune system

Antibiotics and immunoglobulin therapy are two types of medications often used in treatment.

Other antiviral drugs, like oseltamivir and acyclovir, or a drug called interferon are sometimes used for treatment of the viral infections caused by immunodeficiency disorders.

If your bone marrow isn’t producing enough lymphocytes, your doctor might order a bone marrow (stem cell) transplant.

Primary immunodeficiency disorders can be managed and treated, but they can’t be prevented.

The risk of developing secondary disorders can sometimes be lowered through lifestyle choices. For example, it’s possible to lower your risk of developing type 2 diabetes by eating a nutritious diet and getting adequate physical activity.

Sleep is very important for a healthy immune system. According to the CDC, prolonged sleep loss may not only lead to a variety of chronic conditions, it may also weaken your body’s ability to fight off infections.

If your primary care physician has diagnosed you with an immunodeficiency disorder, or suspects you might have one and wants an expert opinion, they will most likely send you to an immunologist.

Immunologists specialize in immunodeficiency disorders. Typically, after acquiring a bachelor’s degree, individuals who want to become immunologists must go through 9 years of additional medical training.

To be board certified, they must pass an exam given by the American Board of Allergy and Immunology (ABAI).

If you’ve been diagnosed with an immunodeficiency disorder, it means that your immune system is not able to fight off infections or viruses effectively. You may have been born with it, or it could have arisen later in life due to a chronic condition, such as diabetes or cancer.

There are hundreds of forms of immunodeficiency disorders. According to the British Society for Immunology, approximately 6 million people worldwide live with a primary immunodeficiency disorder (i.e., they were born with it).

Most doctors agree that people with immunodeficiency disorders can lead full and productive lives. Early identification and treatment of the disorder is very important.


I have a family history of immunodeficiency disorders. If I have children, how early should they be screened for it?

Anonymous person


A family history of primary immunodeficiency is the strongest predictor of a disorder. At birth and for only a few months, babies are partially protected from infections by antibodies transmitted to them by their mothers.

Typically, the earlier any signs of an immunodeficiency show up in children, the more severe the disorder. Testing can be done within the first few months, but it’s also important to recognize the early signs: recurrent infections and failure to thrive.

Initial laboratory screening should include a complete blood count with differential and measurement of serum immunoglobulin and complement levels.

Brenda B. Spriggs, MD, FACPAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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