Symptoms of H1N1 influenza

Symptoms of patients with influenza A are typically characterized by systemic toxic manifestations such as high fever, chills, headache, fatigue, loss of appetite, and muscle aches. Upper respiratory tract symptoms are generally mild; however, a minority of patients may experience cough, nasal congestion, sneezing, runny nose, dryness, sore throat, itching, or hoarseness. Some patients may also develop gastroenteritis symptoms, including vomiting, abdominal pain, diarrhea, and decreased appetite. In more severe cases, patients may develop pneumonia, presenting with persistent high fever, shortness of breath, cyanosis, hemoptysis, extreme exhaustion, or respiratory failure. A smaller number of patients with weakened immune systems may experience prolonged illness and complications such as bacterial pneumonia, toxic shock, or toxic myocarditis.