What causes recurrent infections?

Uncontrolled diabetes, smoking, poor nutrition, chronic stress and sleep loss, HIV or other immune deficiency, immunosuppressive medication, and structural problems like kidney stones or nasal polyps. Repeated severe or unusual infections warrant immune evaluation.

First check the common causes: uncontrolled diabetes, iron or vitamin D deficiency, smoking, poor sleep, and chronic stress.

Features suggesting genuine immune deficiency: infections needing IV antibiotics, unusual organisms, deep-seated infections, or two or more pneumonias in a year.