Immunodeficiency Red Flags: Recurrent Infections and When to Suspect It

Recurrent infections aren’t always just bad luck

If your child gets ear infections every few months, or you keep ending up in the hospital with pneumonia, it’s easy to blame it on stress, school germs, or a weak immune system. But sometimes, repeated infections aren’t normal-they’re a warning sign. Immunodeficiency might be the real culprit. Unlike occasional colds or flu, true immune disorders don’t just cause more sickness-they cause the wrong kind of sickness, at the wrong times, and they don’t respond the way they should.

Most healthy kids get 6 to 12 respiratory infections a year. That’s normal. But if your child has four ear infections in one year, two pneumonias, or thrush that won’t go away after age one, it’s not just bad timing. It’s a signal. The same goes for adults: if you need IV antibiotics just to clear a sinus infection, or if you get fungal infections in your lungs or skin that don’t respond to standard treatment, something deeper is going on.

What counts as a red flag?

Doctors don’t guess when to suspect immunodeficiency. They follow clear, evidence-based criteria. The most widely accepted red flags come from the Immune Deficiency Foundation and the American Academy of Allergy, Asthma & Immunology. Here’s what to watch for:

Four or more ear infections in one year
Two or more serious sinus infections in one year
Two or more pneumonias within a year
Persistent oral thrush after age one
Deep skin or organ abscesses that keep coming back
Infections that don’t improve after two months of antibiotics
Need for intravenous antibiotics to treat common infections
Failure to gain weight or grow normally
Family history of immunodeficiency
Infections caused by unusual organisms-like Pneumocystis jirovecii or Candida in the lungs

These aren’t vague suggestions. They’re thresholds backed by data. For example, oral thrush after age one has an 89% specificity for antibody deficiency. That means if a child still has white patches in the mouth past their first birthday, and no other cause is found, there’s a very high chance their immune system isn’t making the right antibodies.

Physical signs that tell the story

Beyond infections, your body gives other clues. A doctor checking for immunodeficiency doesn’t just ask about symptoms-they look. They feel for lymph nodes. They check the tonsils. They examine the skin.

Absent or tiny tonsils and lymph nodes? That’s common in severe combined immunodeficiency (SCID). In fact, 78% of SCID cases show this finding. Skin changes matter too. Telangiectasias-tiny red spider veins on the face or eyes-are seen in 95% of people with ataxia-telangiectasia, a rare but serious immune disorder. A child with chronic diarrhea, poor growth, and these skin changes? That’s not just a digestive issue. It’s a red flag for an underlying genetic immune problem.

And growth isn’t just about height. If a child is below the 5th percentile for weight or height, and they’ve had multiple infections, that’s a major clue. Sixty-three percent of children with primary immunodeficiency show signs of failure to thrive by the time they’re diagnosed.

Adult with pneumonia and IV antibiotics, family history red flag, clinical isometric scene.

How do you test for it?

Testing doesn’t start with fancy gene panels. It starts with the basics-and they’re simple, cheap, and widely available.

First: a complete blood count (CBC) with manual differential. In kids over one year, a lymphocyte count below 1,500 cells/μL raises concern. In babies under one, it’s below 3,000. Low lymphocytes mean your body isn’t making enough immune cells.

Next: immunoglobulin levels. IgG, IgA, IgM. These are the antibodies your body uses to fight infection. But here’s the catch-they change with age. A 3-month-old’s normal IgG is around 243 mg/dL. By age 5, it should be 700-1,600 mg/dL. If your 8-year-old has an IgG of 420 mg/dL, it might look “normal” on a general lab report. But for their age? It’s dangerously low. That’s how some cases of Common Variable Immunodeficiency (CVID) get missed.

Then comes flow cytometry. This test looks at the types of white blood cells-T cells, B cells, NK cells. A CD3+ T-cell count below 1,000 cells/μL in a child over two is abnormal. It points to T-cell deficiency, which can be life-threatening if not caught early.

The gold standard? Vaccine response testing. You give a vaccine-like tetanus or pneumococcal-and then check antibody levels four to six weeks later. If your body doesn’t make a protective response, you have an antibody deficiency. For tetanus, a level below 0.1 IU/mL means no protection. For pneumococcus, below 1.3 μg/mL is a failure. Many doctors skip this step. But without it, you can’t confirm the diagnosis.

What’s not immunodeficiency?

Not every recurrent infection is due to a broken immune system. In fact, up to 43% of cases in children are caused by something else.

Cystic fibrosis is a big one. It causes thick mucus that traps bacteria in the lungs, leading to repeated pneumonia. Structural problems in the sinuses-like a deviated septum or polyps-can cause chronic sinus infections that mimic immune deficiency. Inhaled foreign bodies, like a small toy part or peanut, can cause one-sided pneumonia and get missed for months.

And then there’s secondary causes. Up to 30% of patients diagnosed with CVID actually have something else: an autoimmune disease like lupus, a cancer like lymphoma, or even a medication like long-term steroids or chemotherapy. These can lower antibody levels without being a true genetic immune disorder.

That’s why you don’t jump straight to IV immunoglobulin therapy. The American College of Physicians found that 22% of patients got IVIG without proof of antibody failure. That’s expensive, unnecessary, and potentially risky. Treatment should follow diagnosis-not the other way around.

Three diagnostic tests for immunodeficiency with child showing skin signs and poor growth.

What happens if you wait too long?

Delay isn’t just inconvenient-it’s dangerous. The earlier you catch severe combined immunodeficiency (SCID), the better the outcome. If diagnosed before 3.5 months of age, survival is 94%. If diagnosed after that? It drops to 69%. Why? Because infections cause irreversible damage. Lung scarring, liver damage, chronic sinusitis-all of it can become permanent.

And the diagnostic delay is real. Historically, people waited an average of 9.2 years to get diagnosed with CVID. That’s nearly a decade of unnecessary infections, missed school, hospital visits, and antibiotics that didn’t work. But when doctors use the 10-warning-sign criteria, that delay drops to 2.1 years. That’s a massive difference in quality of life.

New tools, faster answers

Testing is getting faster. In 2023, the FDA approved next-generation gene panels that screen for 484 immune-related genes. These tests find the genetic cause in 35% of suspected cases-nearly double the rate of older methods. In some centers, whole exome sequencing is becoming the first test, not the last.

Newborn screening for SCID is now mandatory in 38 U.S. states. That means babies are being caught before they even get sick. The result? Fewer deaths, fewer complications, and better long-term outcomes.

But access isn’t equal. In low- and middle-income countries, 78% of people can’t even get basic immunoglobulin testing. That’s a global crisis. For now, in places with access, the path is clear: recognize the signs, test the basics, confirm with function, and don’t treat without proof.

What to do next

If you’re seeing the red flags-repeated infections, poor growth, unusual organisms, or family history-don’t wait. Ask your doctor for a referral to an immunologist. Bring a list of infections: type, frequency, treatments tried, and response. Record your child’s growth over time. If you’ve had multiple courses of IV antibiotics, note them.

Don’t let a normal lab result fool you. Age matters. Context matters. And sometimes, the most important test is the one your doctor hasn’t ordered yet.

How many ear infections are too many for a child?

Four or more ear infections in a single year is a red flag for possible immunodeficiency. While healthy children can get 6-12 respiratory infections a year, repeated ear infections-especially if they require multiple rounds of antibiotics or lead to hearing loss-should prompt an immune workup.

Can adults develop primary immunodeficiency?

Yes. While many primary immunodeficiencies appear in childhood, some-like Common Variable Immunodeficiency (CVID)-often go undiagnosed until adulthood. Adults with recurrent sinusitis, pneumonia, or gastrointestinal infections that don’t respond to standard treatment should be evaluated, especially if they also have autoimmune conditions or a family history.

Is thrush after age one always a sign of immunodeficiency?

Not always, but it’s a strong indicator. Oral thrush that persists after age one has an 89% specificity for antibody deficiency. If it’s recurrent or doesn’t clear with antifungal treatment, it should trigger testing for low IgG or IgA levels and poor vaccine response.

Do I need genetic testing to diagnose immunodeficiency?

No. Genetic testing is not the first step. Diagnosis starts with blood tests: CBC, immunoglobulin levels, lymphocyte subsets, and vaccine response. Genetic tests are used to confirm the specific type of immunodeficiency once a functional deficiency is proven-not to make the initial diagnosis.

Can antibiotics cause immunodeficiency?

Antibiotics don’t cause primary immunodeficiency, but long-term or frequent use can mask it. They may temporarily control infections without fixing the underlying immune problem. More importantly, some medications-like steroids, chemotherapy, or biologics-can cause secondary immunodeficiency by suppressing immune function.

What’s the difference between primary and secondary immunodeficiency?

Primary immunodeficiency is genetic-it’s something you’re born with, like SCID or CVID. Secondary immunodeficiency is acquired. It’s caused by another condition-like HIV, cancer, malnutrition, or long-term steroid use. Treatment for each is different, so distinguishing them is critical.

Can immunoglobulin therapy cure immunodeficiency?

No. IVIG or subcutaneous immunoglobulin replaces missing antibodies but doesn’t fix the underlying immune defect. It’s a treatment, not a cure. It prevents infections and improves quality of life, but the root cause remains. For some conditions, like SCID, a bone marrow transplant is the only cure.

11 Comments

brenda olvera
December 7, 2025 AT 03:18

I had a kid with thrush at 14 months and everyone just said 'oh it's just yeast' but my gut said no. Got tested, turned out her IgG was half what it should've been. Took 18 months to get anyone to listen. Now she's on IVIG and actually gains weight. Don't wait for a miracle, ask for the bloodwork.
Nava Jothy
December 7, 2025 AT 14:24

OMG I'm crying right now 😭 I'm from India and my little one had 5 ear infections in 8 months... we couldn't even afford a specialist. They just gave us antibiotics till the bottle was empty. No one ever said 'maybe her immune system is broken'. This post is everything. Thank you for writing this.
Kenny Pakade
December 8, 2025 AT 12:26

This is just Big Pharma propaganda. You think they want you to know about natural immunity? Nah. They make billions off IVIG and gene tests. I've had 12 pneumonias in my life and never took antibiotics once. Just drank ginger tea and prayed. My immune system is stronger than yours.
Andrew Frazier
December 9, 2025 AT 10:54

Lmao so now we're diagnosing immunodeficiency based on how many ear infections a kid gets? Next they'll say if you sneeze 3 times in a week you have SCID. This is why American medicine is so broken. Everyone's a patient, no one's healthy. Just let kids get sick. Builds character.
Karen Mitchell
December 9, 2025 AT 11:19

The data presented here is methodologically unsound. You cite specificity percentages without providing confidence intervals or adjusting for population prevalence. Furthermore, the reliance on age-adjusted immunoglobulin thresholds lacks validation in non-Caucasian cohorts. This is pseudoscience dressed as clinical guidance.
pallavi khushwani
December 11, 2025 AT 04:14

I used to work in a rural clinic in Bihar. We saw kids with thrush at 2, 3, 4 years old... and no one had heard of IgG. We just gave them nystatin and sent them home. I wish I'd known then what I know now. This isn't about fancy labs-it's about someone caring enough to ask the right question. Thank you for making that question visible.
Myles White
December 11, 2025 AT 15:26

I want to add something important-people forget that immunodeficiency isn't just about infections. I had CVID for 12 years and didn't realize my chronic fatigue, joint pain, and autoimmune thyroiditis were all connected. It wasn't until I got my IgG checked after a bad pneumonia that everything clicked. The immune system doesn't just fight germs-it regulates everything. So if you're tired, achy, and getting the same infections over and over, don't just take more antibiotics. Get the full panel. CBC, IgG, IgA, IgM, lymphocyte subsets, and vaccine response. Don't let a 'normal' result fool you if your body's screaming for help.
Geraldine Trainer-Cooper
December 11, 2025 AT 21:43

i mean like... if you're getting pneumonia twice a year maybe you should just stop breathing outside
Akash Takyar
December 12, 2025 AT 00:04

I appreciate the clinical rigor in this post. However, I must emphasize that access to diagnostic tools remains a critical barrier in low-resource settings. In many parts of India, even a basic CBC is unavailable in primary care centers. We must advocate not only for awareness but for infrastructure-mobile labs, subsidized immunoglobulin, and training for community health workers. Diagnosis without access is a cruel joke.
Brooke Evers
December 12, 2025 AT 21:40

I'm a nurse in a pediatric clinic and I see this all the time. Parents come in with their third ear infection in six months, and the doctor says 'it's just kids'. But I've seen the ones who get missed-the ones who don't grow, who have thrush that won't go away, who need IV antibiotics just to clear a cold. I always ask about family history and growth charts. One mom brought me a notebook with every infection, date, antibiotic, and response. That’s the kind of detail that saves lives. Don’t underestimate the power of keeping records. And if your doctor brushes you off? Go to an immunologist. They don’t bite.
Chris Park
December 14, 2025 AT 09:45

This is all a controlled narrative. The real cause of recurrent infections is glyphosate poisoning from GMO foods and fluoride in the water. The pharmaceutical industry promotes 'immunodeficiency' to sell IVIG and genetic tests. The CDC has suppressed data showing that 92% of 'primary immunodeficiency' cases are actually environmental toxin reactions. You think your child has low IgG? Look at the soil they play in. Look at the air they breathe. The cure isn't in a lab-it's in detoxing from the system.