Influenza (flu) results from a viral infection that affects your respiratory system. This illness tends to come on suddenly. In most cases, people recover with no problems, but in certain populations like the young, elderly and those with compromised immunity, it can lead to complications.

Causes

Three viral strains cause flu. Type A influenza can trigger deadly widespread outbreaks that occur every 10 to 40 years, while type B contributes to smaller outbreaks. The yearly winter flu can result from either of these strains. Type C influenza tends to remain the same and has never been linked with any major outbreaks, according to the Mayo Clinic.

Symptoms

Common symptoms include fever, body pain, headache, dry cough and a sore throat. You might also experience fatigue and decreased appetite. Vomiting and nausea are uncommon. Symptoms are at their peak for the first three or four days of the illness but it can take one to two weeks to recover fully, according to WebMD.

Complications

Complications from influenza include ear infections, inflamed sinus passages (sinusitis), bronchitis, encephalitis (brain inflammation) and pneumonia---the most common and serious.

Treatment

Primary treatment consists of bed rest and adequate fluid intake. The Mayo Clinic considers adequate fluid intake that which produces pale or clear urine. Your doctor might give you an antiviral drug that targets the influenza viruses specifically. Pain relievers can alleviate body aches.

Prevention

Getting a flu vaccine, washing your hands regularly, eating right, exercising, getting enough sleep and avoiding areas with lots of people during flu season can prevent infection, according to the Mayo Clinic.

Source:

WebMD: Influenza--Topic Overview

The Mayo Clinic: Influenza (flu)