Symptoms often include extreme fatigue, muscle aches, high fever with chills, headache, cough, sore throat and runny or stuffy nose. Stomach related symptoms such as nausea, vomiting and diarrhea are generally not associated with the flu. Most people recover from the flu in 1 - 2 weeks. However, some people, especially the elderly, have flu-related complications that can be serious. The flu can lead to serious complications, some of which can be life threatening.
Some people develop influenza pneumonia or a secondary bacterial pneumonia.
Other complications include Reye's syndrome, myositis and Guillain-Barre syndrome. Myocarditis and pericarditis, which affect the heart, have also been linked to the flu. People with asthma and other chronic lung diseases may have worsening of respiratory symptoms that require stronger treatment. People with chronic lung disease also have a higher risk of developing pneumonia from influenza. Fortunately, a flu vaccine is available.