Recurring Infections: Why You Keep Getting Sick

How many infections is too many?

Healthy young children get 6 to 8 colds a year, sometimes more in their first year of daycare. Adults get 2 to 4 colds a year. These are normal and do not suggest a weak immune system, as long as recovery is complete.

Concern rises with infections that are:

• Serious: pneumonia, meningitis, bone infections or sepsis
• Persistent: not clearing despite appropriate treatment
• Unusual: caused by germs that rarely affect healthy people, such as Pneumocystis pneumonia
• Recurrent: the same type again and again, especially needing antibiotics
• Running in the family

Warning signs of primary immunodeficiency

Adapted from the Jeffrey Modell Foundation warning signs for children:

1. Four or more ear infections within a year
2. Two or more serious sinus infections within a year
3. Two or more months on antibiotics with little effect
4. Two or more pneumonias within a year
5. Failure to gain weight or grow normally
6. Recurrent deep skin or organ abscesses
7. Persistent thrush in the mouth or fungal skin infection
8. Need for IV antibiotics to clear infections
9. Two or more deep-seated infections, including sepsis
10. A family history of primary immunodeficiency

Two or more of these warrant evaluation by an immunologist.

Common causes of recurring infections

Exposure and lifestyle

• Daycare, school and young children at home
• Smoking and vaping, which damage airway defenses and raise the risk of chest and sinus infections
• Poor sleep, high stress and heavy alcohol use
• Malnutrition and low zinc or vitamin D

Local problems in one area

When the same site keeps getting infected, the cause is often local:

• Sinuses: allergies, nasal polyps or a deviated septum leading to chronic sinusitis
• Ears: large adenoids or Eustachian tube problems in children
• Lungs: asthma, COPD, bronchiectasis, cystic fibrosis or an inhaled foreign body (one lung area affected repeatedly)
• Urinary tract: sexual activity, menopause, incomplete bladder emptying, kidney stones or abnormal anatomy. See recurrent UTI
• Skin: eczema, carrying Staph aureus in the nose (recurrent boils), and poor circulation

Medical conditions that weaken immunity (secondary immunodeficiency)

• Diabetes: high blood sugar impairs white cells, raising the risk of skin, urinary, foot and fungal infections
• HIV infection
• Medicines: steroids, chemotherapy, transplant drugs and biologic treatments for autoimmune conditions
• Blood cancers such as leukemia, lymphoma, myeloma and chronic lymphocytic leukemia, which reduce antibody production
• No spleen or a non-working spleen (after splenectomy or in sickle cell disease)
• Chronic kidney or liver disease
• Neutropenia: low neutrophils from medicines, cancer treatment or bone marrow problems
• Protein loss through the gut or kidneys

Primary immunodeficiency

Primary immunodeficiencies are inherited conditions in which part of the immune system is missing or does not work. More than 450 types are known. Many are diagnosed in childhood, but some, especially common variable immunodeficiency (CVID), often appear in adulthood with recurrent sinus and chest infections. Selective IgA deficiency is the most common type and often causes few problems.

The type of infection gives clues

How doctors investigate recurring infections

1. History: how many infections, what type, how they were confirmed, antibiotics needed, growth in children, family history, medicines and lifestyle.
2. Examination: growth, ears, sinuses, chest, skin, lymph nodes, tonsils and spleen.
3. First tests: - complete blood count with differential - immunoglobulins (IgG, IgA, IgM) - HIV test - blood sugar or HbA1c - kidney and liver function, protein levels
4. Specialist tests: antibody responses to vaccines, lymphocyte subsets, complement tests and genetic testing.
5. Local investigations: sinus CT, chest CT, kidney ultrasound, allergy testing or sweat test depending on the pattern.

Treatment and prevention

• Treat the underlying cause: control blood sugar, stop smoking, treat allergies and asthma, or adjust immune-suppressing medicines where possible.
• Vaccinations: flu, COVID-19, pneumococcal and others as advised. People without a spleen need extra vaccines. Live vaccines may be unsafe in some immune deficiencies.
• Preventive antibiotics for some people, such as those with recurrent UTIs or no spleen.
• Immunoglobulin replacement therapy (IV or under the skin) for antibody deficiencies like CVID.
• Surgery for local problems, such as sinus surgery or ear tubes.
• Stem cell transplant or gene therapy for some severe inherited immune deficiencies.
• Daily habits: handwashing, adequate sleep, a balanced diet and regular exercise support normal immunity.

Frequently asked questions

Why do I keep getting infections?

Most adults with frequent infections have an identifiable trigger: smoking, poorly controlled diabetes, allergies, asthma, young children at home, stress or a local problem such as sinus blockage. Less often, medicines, HIV, cancer or an inherited immune deficiency weaken defenses. A doctor can start with simple blood tests.

What are the signs of a weak immune system?

Signs include frequent infections that need antibiotics, pneumonia more than once, infections that take a long time to clear, recurrent abscesses, persistent thrush, unusual infections, and in children, poor growth. A family history of immune problems also raises suspicion.

What blood tests check for immune deficiency?

Initial tests are a complete blood count, immunoglobulin levels (IgG, IgA, IgM), an HIV test and blood sugar. If these suggest a problem, an immunologist may check vaccine antibody responses, lymphocyte subsets and complement levels, and sometimes genetic tests.

Is it normal for my child to be sick all the time?

Young children often catch 6 to 8 or more colds a year, especially in daycare. That is normal if they grow well and recover fully between illnesses. See your pediatrician for repeated pneumonias, ear infections that need many antibiotic courses, poor weight gain or severe infections.