What is the flu?
Influenza is a viral infection that attacks your respiratory system — your nose, throat and lungs. Influenza is commonly called the flu, but it’s not the same as stomach “flu” viruses that cause diarrhea and vomiting.
For most people, influenza resolves on its own. But sometimes, influenza and its complications can be deadly. People at higher risk of developing flu complications include:
- Young children under age 5, and especially those under 2 years
- Adults older than age 65
- Residents of nursing homes and other long-term care facilities
- Pregnant women and women up to two weeks postpartum
- People with weakened immune systems
- People who have chronic illnesses such as asthma, heart disease, kidney disease, liver disease and diabetes
- People who are very obese, with a body mass index (BMI) of 40 or higher
The annual influenza vaccine is your best defense against the flu.
Common signs and symptoms of the flu include:
– Fever over 100.4 F (38 C)
– Aching muscles, especially in your back, arms and legs
– Chills and sweats
– Dry, persistent cough
– Fatigue and weakness
– Nasal congestion
– Sore throat
A bout of the flu typically lasts one to two weeks, with severe symptoms subsiding in two to three days. However, weakness, fatigue, dry cough, and a reduced ability to exercise can linger for three to seven days.
While the symptoms of influenza B mirrors those of A, the main difference between the two strains is who it can affect. This allows strains of A to be spread more rapidly than B, while also meaning strains of B cannot cause pandemics with symptoms likely less severe. Flu shots protect against both strains of influenza.
The Flu Is Contagious. Most healthy adults may be able to infect other people beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children may pass the virus for longer than 7 days. Symptoms start 1 to 4 days after the virus enters the body.