Health condition
Recurrent infections in adults
Adults who suffer infections that are unusually frequent, severe, prolonged or hard to clear may have an underlying cause - from diabetes and medications to antibody deficiency - and a structured review beats another round of antibiotics.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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Rough thresholds that warrant review: more than 2 courses of antibiotics a year for chest infections, more than one pneumonia, recurrent sinusitis despite treatment, or infections that repeatedly need intravenous antibiotics or hospital care
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The common contributors first: smoking, diabetes, medications (steroids, immunosuppressants, some biologics), structural problems (bronchiectasis, sinus disease), and HIV - all screened before rare diagnoses
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Antibody deficiency is the key treatable immune cause in adults - screened with immunoglobulin levels (IgG, IgA, IgM) and vaccine response testing
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Specialist: a consultant immunologist; the pattern of infections (which organs, which organisms) maps which arm of immunity is struggling
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
Immunity fails in patterns, and the pattern is diagnostic: recurrent bacterial infections of the sinuses, ears and chest point towards antibody deficiency - the commonest and most treatable adult immunodeficiency territory - while abscesses and skin infections, severe viral and fungal problems, and infections with unusual organisms each implicate different immune arms; meanwhile the majority of adults referred with recurrent infection turn out to have amplifiers rather than immune failure: smoking and airway damage, undiagnosed or poorly controlled diabetes, immunosuppressive medications whose infection cost was never totted up, anatomical havens like bronchiectatic airways and chronically diseased sinuses where organisms persist between courses, and reflux or aspiration feeding the chest. The structured review therefore works both lists at once - the amplifiers, through history, HbA1c, imaging and medication audit, and the immune system itself, through a screen whose adult centrepiece is immunoglobulin measurement.
Diagnosis and treatment routes
The immunology work-up escalates logically: full blood count with differential, immunoglobulin levels (IgG, IgA, IgM), serum electrophoresis in older adults (paraproteins and their diseases suppress normal antibodies), HIV testing as standard, then functional assessment - specific antibody levels against pneumococcus and tetanus, repeated after test vaccination to see whether the system can respond, the step that catches deficiencies invisible on static levels. What follows ranges from the corrective (diabetes control, smoking cessation, sinus surgery, airway clearance regimes for bronchiectasis) through the preventive (vaccination optimisation, prophylactic antibiotic strategies over winter) to the definitive for confirmed significant antibody deficiency: immunoglobulin replacement therapy, which transforms infection frequency and protects organs from the cumulative damage - and identifying that group is the reason the threshold for checking immunoglobulins in recurrent, severe or unusual infection deserves to be low. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant immunologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Recurrent infections in adults.
Quick, plain-English answers to what people ask us most.
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What counts as recurrent infections in adults needing investigation?
Infections that are unusually frequent, more severe than expected, prolonged, or hard to clear with standard treatment suggest an underlying cause may exist, from diabetes and certain medications to antibody deficiency, rather than simple bad luck.
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What causes recurrent infections in adults?
Common contributors include poorly controlled diabetes, immunosuppressive medications, alcohol excess, and less commonly primary or secondary antibody deficiencies, chronic conditions like COPD, or structural problems such as blocked sinuses.
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How are recurrent infections in adults investigated?
A structured review typically includes blood tests to check immune function and antibody levels, assessment for underlying conditions such as diabetes, and consideration of imaging depending on which site is affected.
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Is recurrent infection a sign of a serious immune problem?
Not always - many cases relate to manageable factors like diabetes control - but a genuine pattern of severe, unusual or hard-to-treat infections warrants proper immune assessment rather than repeated antibiotic courses alone.
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How are recurrent infections in adults treated?
Treatment depends on the cause found - optimising diabetes control, reviewing medications, or for confirmed antibody deficiency, immunoglobulin replacement therapy alongside prompt treatment of individual infections.
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Recurrent infections vs normal susceptibility - what's the difference?
Everyone gets occasional infections, but a pattern that is more frequent, severe or persistent than typical for your age and health status is what prompts a structured immune and metabolic review.
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When should I see a doctor about recurrent infections?
See your GP if infections are becoming noticeably more frequent or severe, and ask about referral to an immunologist if no obvious cause is found. A private consultant immunologist can typically be seen within about two weeks.