When congestion after flu signals a bacterial infection

Persistent congestion or cough after a fever subsides from the flu can be a normal part of recovery, but worsening symptoms may signal a secondary bacterial infection requiring medical evaluation. Experts advise monitoring for specific warning signs. The lingering symptoms stem from ongoing inflammation in the respiratory tract, which can cause airway narrowing, mucus buildup, and postnasal drip even after the virus is controlled. A change in mucus color from whitish to greenish or yellowish may indicate a bacterial infection, though this alone is not definitive. Patients should consult a respiratory physician if they experience chest pain, wheezing, excessive coughing, breathing difficulty, or worsening symptoms after initial improvement. Urgent care is needed for severe breathing problems, chest pain, bluish lips, or confusion. Most people recover without complications, but persistent chest symptoms should not be ignored.