According to the Centers for Disease Control and Prevention, seasonal flu is a contagious respiratory disease that affects 5 to 20 percent of Americans each year. In most people, seasonal flu resolves without treatment, although symptoms may last anywhere from 2 days to 2 weeks. While the symptoms of seasonal flu and the common cold overlap, symptoms of seasonal flu can usually be distinguished by greater severity and abrupt onset, notes the American Academy of Family Physicians.
Systemic Symptoms
Systemic symptoms reflect the response of the immune system to infection and affect the entire body rather than a single organ system. According to the American Academy of Family Physicians, systemic symptoms of seasonal flu include fever over 102 degrees F, chills and sweats, body aches (especially in the back, arms, and legs), headache and fatigue. However, not everyone with flu will have a fever, cautions the CDC. Some people, especially the elderly, infants and people with medical problems, do not develop a fever in response to seasonal flu.
Respiratory Symptoms
Seasonal flu is associated with both upper and lower respiratory symptoms. Lower respiratory symptoms of seasonal flu include cough and, in severe cases, breathing problems, including pneumonia. Upper respiratory symptoms of seasonal flu, according to the CDC, can include sore throat, runny nose and/or stuffy nose. The cough associated with seasonal flu is usually dry. Cough that produces green or yellow sputum or copious amounts of clear sputum may reflect another kind of infection or an allergic reaction.
Gastrointestinal Symptoms
Gastrointestinal symptoms of seasonal flu include loss of appetite, nausea, vomiting and diarrhea. According to the CDC,nausea, vomiting and diarrhea, are more common in children than adults. One exception, however, is the H1N1 (swine) flu. According to a 2009 report in the "New England Journal of Medicine," nearly 40 percent of adults and children with swine flu reported vomiting, diarrhea or both.
References
- CDC: Key Facts About Seasonal Flu
- American Academy of Family Physicians: Colds and the Flu
- "New England Journal of Medicine;" Emergence of a Novel Swine-Origin Influenza A (H1N1) Virus in Humans; Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team; June 18, 2009
