IgA Deficiency: Causes, Symptoms, Infection Risks, And Treatment

Your immune system relies on several different antibodies to protect your body from infections. One of these is immunoglobulin A, or IgA. It works quietly in the background, guarding the surfaces of your airways, digestive tract, eyes, and ears. When your body does not produce enough of it, the result is IgA deficiency.

For many people, this condition causes no noticeable symptoms at all. Others may find themselves dealing with frequent infections, persistent digestive issues, or related immune conditions. The reassuring news is that with the right awareness and follow-up care, most people with IgA deficiency manage well.

This article explains what IgA deficiency is, what causes it, how it is diagnosed, and what you can do to protect your health.

What Is IgA Deficiency?

IgA deficiency is a condition in which your body does not produce adequate amounts of immunoglobulin A, an antibody that plays a key role in protecting the mucosal surfaces of your body. It is classified as a primary immunodeficiency disorder, meaning it relates to an underlying issue with how your immune system is built rather than being caused by an external illness or medication.

It is one of the more common primary immunodeficiencies, estimated to affect around 1 in 500 people of European descent. Many people who have it are never diagnosed because they never experience significant symptoms.

What Does IgA Do In The Body?

IgA is found in two main places: your blood and your secretions. The secretory form of IgA is the more active defender. It is present in saliva, tears, breast milk, and the fluids that line your airways, digestive tract, and genitourinary tract.

Its job is to act as a first line of defence against bacteria, viruses, and parasites that try to enter your body through these mucosal surfaces. It helps keep harmful microorganisms from attaching to and crossing the tissue lining of your:

• Respiratory tract, including your nose, sinuses, and lungs
• Digestive tract, from mouth to gut
• Eyes and ears
• Urinary and genital tract

Without adequate IgA, these surfaces are more vulnerable to infection.

What Is Selective IgA Deficiency?

Selective IgA deficiency, also known as SIgAD or low IgA, is the most clinically recognised form of this condition. It is defined as having undetectable or very low levels of IgA in the blood and secretions, while all other immunoglobulin types, particularly IgG and IgM, remain at normal levels.

Key points to understand:

• IgA levels are very low or completely absent
• IgG and IgM levels are typically normal, meaning much of the immune system continues to function
• Many people with selective IgA deficiency have no symptoms and are diagnosed by chance during testing for something else
• Others may experience recurrent infections, allergies, or conditions linked to immune imbalance

The condition exists on a spectrum. Some people live their entire lives without any issue. Others require ongoing medical attention.

Causes Of IgA Deficiency

The exact cause of IgA deficiency is not fully understood. In most cases, the immune system's B cells, which are responsible for producing antibodies, do not function correctly. As a result, they produce little to no IgA.

Is IgA Deficiency Genetic?

IgA deficiency often runs in families. Research suggests that genetic susceptibility plays a role in many cases, and family history is one of the strongest risk factors. If one of your biological parents has the condition, your risk of having it is significantly higher than that of the general population.

Certain gene variations appear to be linked with selective IgA deficiency, though no single gene has been identified as the direct cause. The condition can be inherited in different patterns, making its genetics complex.

Can Medicines Trigger Low IgA?

In some cases, low IgA has been associated with certain medications. Medicines used to manage seizures, epilepsy, or rheumatoid arthritis have been linked to reduced IgA levels in some individuals. In these situations, low IgA may persist even after the medicine is discontinued.

If you are on long-term medication and have concerns about your immune function, speak with your doctor.

Symptoms Of IgA Deficiency

A significant number of people with IgA deficiency have no symptoms at all. The condition is often discovered incidentally when a blood test is done for another reason. However, for those who do experience symptoms, the following are the most commonly reported:

• Frequent ear infections, particularly in young children
• Recurrent sinus infections
• Repeated colds or upper respiratory tract infections
• Bronchitis that keeps coming back
• Pneumonia
• Chronic diarrhoea or other digestive disturbances
• Gastrointestinal infections
• Allergies or asthma in some cases

The frequency and severity of symptoms vary considerably from one person to the next. Having some of these symptoms does not automatically mean you have IgA deficiency, but repeated or unexplained infections are worth discussing with your doctor.

IgA Deficiency And Infection Risks

Because IgA acts as a guardian of the body's mucosal surfaces, its absence creates gaps in your natural defences. Without adequate IgA, bacteria and viruses that enter through the nose, mouth, or gut may find it easier to take hold and cause infection.

This does not mean that people with IgA deficiency are constantly unwell. The rest of the immune system, including IgG and IgM antibodies and cellular immunity, continues to function. But certain types of infections may occur more often and may take longer to resolve.

Common Infections Seen In IgA Deficiency

The infections most commonly associated with IgA deficiency are those involving the respiratory and digestive systems:

• Ear infections: Particularly common in children with this condition
• Sinus infections: Recurrent sinusitis is a frequent concern
• Bronchitis: Inflammation of the airways that may return repeatedly
• Pneumonia: A more serious lung infection that can develop in some cases
• Gastrointestinal infections: Including parasitic conditions such as giardiasis that cause persistent diarrhoea

Why Some People Get Repeated Infections

When IgA is absent or very low, the mucosal lining is less protected against pathogens. The body's other immune tools can step in to some degree, but they are not designed to act at the mucosal surface in the same way IgA does. This means infections in the airways and gut may be harder to prevent and take longer to clear, sometimes leading to repeated episodes.

IgA Deficiency And Autoimmune Conditions

IgA deficiency does not only affect how your body handles infections. In some people, it is also associated with an increased risk of autoimmune conditions, where the immune system mistakenly attacks the body's own tissues.

Approximately one-third of people who seek medical help for IgA deficiency are found to have an associated autoimmune condition. IgA normally helps regulate how the immune system interacts with the body's own tissues, so when it is absent, this regulatory function may be disrupted.

Conditions Linked With IgA Deficiency

Autoimmune diseases that have been associated with selective IgA deficiency include:

• Rheumatoid arthritis: A condition that causes joint inflammation and pain
• Celiac disease: An immune reaction to gluten that damages the small intestine
• Lupus (systemic lupus erythematosus): A wide-ranging autoimmune condition affecting multiple organs
• Inflammatory bowel disease: Including conditions such as Crohn's disease and ulcerative colitis
• Idiopathic thrombocytopenic purpura: A condition affecting platelet counts

If you have been diagnosed with any of these autoimmune diseases, your doctor may test your immunoglobulin levels as part of a broader evaluation. Learning more about autoimmune diseases and how they interact with immune deficiencies can help you ask the right questions and stay informed about your health.

IgA Deficiency And Allergies

Allergies and asthma are also more common among people with selective IgA deficiency than in the general population. The relationship between IgA and the immune response to environmental triggers is still being studied, but the association is well recognised.

Types of allergic conditions seen alongside IgA deficiency include:

• Allergic rhinitis (hay fever)
• Allergic conjunctivitis (itchy, watery eyes)
• Eczema
• Asthma
• Food allergies

If you have IgA deficiency and notice persistent or worsening allergy symptoms, discuss them with your doctor. Managing allergies well can reduce their impact on your daily life and overall immune burden.

How IgA Deficiency Is Diagnosed

IgA deficiency is often diagnosed by chance. Many people are tested for an unrelated concern, and low IgA shows up in the results. In others, the diagnosis follows a pattern of repeated infections or the identification of a related condition.

When Doctors May Suspect IgA Deficiency

A doctor may consider testing for IgA deficiency if you:

• Experience frequent or unusually severe infections
• Have ongoing digestive symptoms without a clear cause
• Have a known family history of IgA deficiency or primary immunodeficiency
• Are being evaluated for an autoimmune condition such as celiac disease or rheumatoid arthritis
• Have repeated respiratory infections that do not resolve as expected

Blood Tests Used To Diagnose IgA Deficiency

The diagnosis is established through a blood test that measures serum IgA levels. A reading of less than 7 mg/dL in a person aged four years or older, alongside normal IgG and IgM levels, confirms selective IgA deficiency.

Your doctor will typically also measure your IgG and IgM levels to confirm they are within a normal range. Additional blood tests may be ordered depending on your symptoms, including tests for autoantibodies if an autoimmune condition is suspected.

Can IgA Deficiency Affect Blood Transfusions?

This is an important consideration that is sometimes overlooked. Some people with selective IgA deficiency carry antibodies that react against IgA. If they receive blood or blood products that contain IgA, such as standard blood transfusions, this can trigger an immune reaction.

Reactions can range from fever and chills to, in rare cases, a severe allergic reaction known as anaphylaxis. For this reason, people with IgA deficiency are advised to inform their healthcare providers before any procedure involving blood products. Wearing a medical identification bracelet is also recommended so that medical teams are aware of this risk in emergency situations.

If you have been diagnosed with selective IgA deficiency, make sure this is documented in your medical records and communicated to any new healthcare providers.

Is There A Cure For IgA Deficiency?

This is one of the most common questions people ask after a diagnosis, and it is worth addressing clearly.

There is currently no specific cure for IgA deficiency. The immune system's inability to produce IgA cannot be corrected with available treatments. Unlike some immunodeficiency conditions where immunoglobulin replacement therapy is used, IgA replacement is not currently possible because no IgA-specific preparation is available.

Some children with IgA deficiency begin producing normal amounts of IgA as they grow and develop. This is not guaranteed and cannot be predicted, but it does happen in some cases.

The focus of management is therefore on treating the infections and related conditions that arise, rather than fixing the underlying deficiency itself.

Treatment And Management Of IgA Deficiency

While there is no cure, IgA deficiency is manageable. The approach depends on what symptoms or related conditions you have. A good relationship with your doctor and timely medical care make a significant difference.

Key aspects of management include:

• Treating infections promptly: Early treatment with appropriate antibiotics prevents infections from becoming more serious
• Antibiotic therapy: Some people with chronic sinusitis or recurring bronchitis may need longer-term antibiotic use, as guided by their doctor
• Monitoring recurring symptoms: Keeping track of how often infections occur helps your doctor adjust your care plan
• Managing allergies and asthma: Treatment for these conditions reduces their impact on quality of life
• Treating associated autoimmune conditions: Options include anti-inflammatory medicines, steroids, or other therapies depending on the specific condition
• Immunoglobulin replacement: For people with both IgA deficiency and IgG2 subclass deficiency who have serious recurring infections, subcutaneous immunoglobulin may be considered with appropriate precautions
• Regular follow-up with your doctor: Ongoing review allows for early identification of any new or worsening conditions
• Specialist care: An immunologist or rheumatologist may be involved in your care depending on your individual circumstances

Living With IgA Deficiency

Most people with selective IgA deficiency live healthy, fulfilling lives. The condition is considered one of the milder forms of primary immunodeficiency, though this does not diminish the impact it can have for those who experience frequent illness.

Understanding your own pattern of health is one of the most useful things you can do. Knowing how often you get sick, which infections tend to recur, and how long recovery usually takes gives both you and your doctor valuable information.

Open communication with your healthcare team is key. Reporting new or unusual symptoms early, such as a productive cough, skin changes, joint discomfort, or prolonged fatigue, allows for prompt evaluation and treatment.

IgA Deficiency In Children Vs Adults

IgA deficiency can present differently depending on age:

• In children: The most common presentations are repeated ear infections and sinus infections. Children with frequent illness that does not follow the usual pattern may be evaluated for immune conditions. Some children improve spontaneously as they grow
• In adults: Diagnosis often happens later in life, sometimes when being tested for an unrelated condition such as celiac disease or an autoimmune disorder. Adults may also present with chronic sinusitis, recurring respiratory infections, or digestive symptoms
• In both groups: Severity varies widely. Many never need treatment, while others require active management of infections or related conditions

How To Reduce Infection Risk In Daily Life

While you cannot increase your IgA levels through lifestyle measures, you can take steps to reduce your exposure to infections and support your overall immune function:

• Wash your hands regularly and thoroughly, particularly before meals and after being in public spaces
• Avoid close contact with people who are unwell, especially during cold and flu season
• Seek medical attention early when an infection starts rather than waiting to see if it passes
• Follow your doctor's guidance on vaccinations, as these can help your immune system respond to specific threats
• Keep a simple record of how often you get infections and how long they last; this information is useful for your doctor
• Eat a balanced diet, stay hydrated, and get adequate rest to support your general health

When Should You See A Doctor?

It is worth speaking to a doctor if you notice any of the following:

• You seem to get sick more often than those around you
• Your infections tend to come back shortly after recovering
• You take longer than usual to recover from common illnesses such as a cold or sinus infection
• You have persistent or unexplained digestive problems such as chronic diarrhoea
• You experience ongoing fatigue alongside other symptoms
• You have a family member with IgA deficiency or a known primary immunodeficiency

You should not feel that repeated illness is simply something to put up with. A straightforward blood test can provide important information about your immune function.

Conclusion

IgA deficiency is a common form of primary immunodeficiency that affects part of the immune system's ability to protect mucosal surfaces. Many people who have it never experience any symptoms and live completely normal lives. Others may face recurring infections, allergies, or conditions linked to immune imbalance, all of which can be managed with proper care.

Early diagnosis is often the most important step. Because this condition is frequently discovered through routine blood testing rather than through dramatic symptoms, knowing your immune health markers can make a real difference. If you have concerns about recurring infections, digestive issues, or a family history of immune conditions, getting tested is a practical and reassuring first step.

At Metropolis Healthcare, you can book immunoglobulin blood tests, full body health checkups, and a wide range of diagnostic tests with ease. With home sample collection available across a large network, quick turnaround times, and accurate, reliable reports, staying informed about your health has never been simpler. Book through the Metropolis website, app, call, or WhatsApp, and take a proactive step towards understanding your health.

FAQs

What Is The Difference Between IgA Deficiency And Selective IgA Deficiency?

IgA deficiency is the general term for having low or absent immunoglobulin A. Selective IgA deficiency specifically refers to the condition where IgA is undetectable or very low while all other immunoglobulins, particularly IgG and IgM, remain at normal levels. Selective IgA deficiency is the most common and recognised form of IgA deficiency.

Is IgA Deficiency Genetic?

In many cases, yes. IgA deficiency often runs in families and is associated with certain inherited gene variations. If a close biological relative has the condition, your risk is higher than average. However, no single gene has been confirmed as the direct cause, and in some individuals the condition arises without a clear family history.

What Are The Most Common IgA Deficiency Symptoms?

Many people have no symptoms at all. For those who do, the most common include frequent ear infections, recurring sinus infections, repeated colds or upper respiratory infections, bronchitis, and digestive issues such as chronic diarrhoea. Some people also experience allergies or asthma.

Does IgA Deficiency Increase The Risk Of Pneumonia?

Yes, in some cases. Because IgA helps protect the airways and lungs from infection, its absence can make it easier for respiratory infections to develop or worsen. Pneumonia is among the infections that may occur more frequently or more severely in people with IgA deficiency who are symptomatic.

Can IgA Deficiency Cause Allergies?

Allergic conditions are more commonly seen in people with selective IgA deficiency than in the general population. This includes allergic rhinitis, asthma, eczema, allergic conjunctivitis, and food allergies. The link between IgA and immune regulation of allergic responses is an active area of research.

Is There A Cure For IgA Deficiency?

Currently, there is no cure for IgA deficiency. There is no available treatment that can restore IgA production. Management focuses on treating infections and related conditions as they arise. Some children with this condition begin producing normal IgA as they grow, but this cannot be predicted or guaranteed.

How Is IgA Deficiency Diagnosed Through Blood Tests?

A blood test measuring serum immunoglobulin A levels is used to diagnose IgA deficiency. A level below 7 mg/dL in a person aged four or older, combined with normal IgG and IgM levels, confirms selective IgA deficiency. Additional tests may be ordered depending on symptoms, including tests for autoantibodies or other immunoglobulin subclasses.

Can IgA Deficiency Affect Blood Transfusions?

Yes. Some people with selective IgA deficiency develop antibodies against IgA. If they receive blood or blood products containing IgA, this can trigger a reaction ranging from fever and chills to, in rare cases, a serious allergic reaction. It is important to inform all healthcare providers about an IgA deficiency diagnosis before any procedure involving blood products.

Do All People With IgA Deficiency Have Symptoms?

No. A significant number of people with IgA deficiency have no symptoms whatsoever and are diagnosed only when a blood test is done for another reason. Those who do develop symptoms vary widely in terms of severity. Some may have only occasional infections, while others may experience frequent illness requiring ongoing management.

When Should You Seek Medical Advice For IgA Deficiency?

Speak to a doctor if you are getting sick more often than usual, if infections keep returning shortly after recovery, if you are taking longer than expected to recover from common illnesses, or if you have persistent digestive symptoms or unexplained fatigue. A family history of IgA deficiency or primary immunodeficiency is also a reason to ask your doctor about testing.

References

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Mayo Clinic. Selective IgA deficiency. mayoclinic.org. Accessed 2024.

Cleveland Clinic. IgA deficiency. clevelandclinic.org. Accessed 2024.

Immune Deficiency Foundation. Selective IgA deficiency. Chapter in: IDF Patient and Family Handbook for Primary Immunodeficiency Diseases, 6th ed.

Cunningham-Rundles C. Physiology of IgA and IgA deficiency. J Clin Immunol. 2001;21(5):303-309. PMID: 11720003.