The Centers for Disease Control and Prevention (CDC) report that flu affects millions of Americans each year, causing symptoms such as fever, dry cough, headache, muscle pain and fatigue. A productive cough with the flu usually signals the presence of flu-related complications. People with flu-related complications need to visit their health care provider because complications rarely resolve on their own. Symptoms that interfere with breathing warrant a trip to the emergency room.
The cough associated with flu is dry or "nonproductive." Small amounts of clear or blood-tinged sputum may be normal. Large amounts of sputum or green, yellow or significantly bloody sputum is not normal.
Complications of the Flu
Cough that starts out dry and produces green, yellow or copious amounts of clear or bloody sputum a few days later often signals the presence of a flu-related complication such as a secondary bacterial infection. Complications typically present as new or worsening symptoms in a patient who was previously starting to recover. People with this history should contact their health care provider because complications rarely resolve on their own.
Pneumonia, notes Dr. Dolin in Harrison's Principles of Internal Medicine, is the most common complication of the flu and one of the most serious. Common symptoms of pneumonia, according to the American Lung Association, include shaking chills, shortness of breath either at rest or with exertion, sharp or stabbing chest pain with a deep breath or cough and profuse sweating in addition to productive cough and fever.
According to the CDC, some people are more likely than others to develop complications of the flu. High-risk groups include children younger than age 5 years, adults older than 65 years, women who are pregnant and up to two weeks postpartum, and people with medical problems such as asthma or heart disease.
Emergency Warning Signs
An internist, pediatrician or family doctor can manage most complications of the flu on an outpatient basis; however, some symptoms merit more urgent evaluation. According to the CDC, signs that it's time to go to the emergency department include fast breathing (12 to 18 breaths per minute is normal); effortful breathing; shortness of breath; chest pain; bluish color at the tips of the fingers, toes or around the mouth; and altered mental status (inability to wake up, trouble staying awake, not responding normally to questions or commands).
- Centers for Disease Control and Prevention: Seasonal Influenza
- Influenza (Chapter); R. Dolin; In: “Harrison’s Principles of Internal Medicine, 17th edition;” A.S. Fauci, E. Braunwald, D.L. Kasper, S.L. Hauser, D.L. Longer, J.L. Jameson and J. Loscalzo (Eds.); 2008
- American Lung Association: Pneumonia Symptoms, Diagnosis and Treatment
- Centers for Disease Control and Prevention: Key Facts About Influenza (Flu) & Flu Vaccine
- Centers for Disease Control and Prevention: Flu Symptoms and Severity