Exams and Tests

Doctors can diagnose influenza (flu) using your symptoms alone if many cases of a similar illness have occurred in the community and if the local health department has confirmed a flu outbreak.

Tests to confirm you have the flu and to determine the type of virus may be important if:

• The results may affect treatment decisions. During a confirmed flu outbreak, however, testing may not be needed even if treatment with an antiviral medicine is being considered.
• In addition to flu-like symptoms, you have any unusual symptoms that suggest another condition.
• Health authorities have not identified any other cases of flu in your area.

Testing may involve blood tests (rarely used) or a culture to identify the virus. Some cultures take 24 to 48 hours for results, so they will not help your doctor decide whether to prescribe an antiviral medicine. A rapid flu test is now available that gives results in 30 minutes. Although this test is not 100% accurate, it can be useful when deciding whether to use an antiviral medicine.

Treatment Overview

In most healthy people, influenza (flu) will go away in 5 to 7 days. The worst symptoms usually last 3 to 4 days. Home treatment to ease symptoms and prevent complications is usually all that is needed.

Antiviral medicines can be taken to:

• Reduce the severity and duration of symptoms caused by infection with influenza A or B virus.
• Shorten the length of the illness.
• Control outbreaks of the flu in nursing homes.
• Reduce the spread of the virus to people at high risk for severe complications of the flu (high-risk groups).
• Reduce complications from the flu.

People at high risk of complications are encouraged to contact a doctor within 48 hours of their first symptoms to find out whether they need medicine to shorten the illness. They also should call a doctor to receive medicine if they have been exposed to the flu.

Flu: Should I Take Antiviral Medicine?

If medicines are not used, contact your doctor if symptoms of a complication develop.

What to think about

Yearly immunization with the inactivated influenza vaccine(What is a PDF document?) (flu shot) or the nasal spray flu vaccine(What is a PDF document?) prevents flu infection and its complications in most people. The nasal spray vaccine is approved for use by healthy people who are 2 to 49 years old. You should not get the nasal spray vaccine if you:

• Have heart disease.
• Have lung disease, including asthma.
• Have diabetes or kidney disease.
• Have a disease or take a medicine that causes problems with your immune system.
• Have a condition (such as a seizure disorder or cerebral palsy) that can cause breathing or swallowing problems.
• Are pregnant.
• Are younger than age 20 and you take aspirin or products with aspirin in them.

Before getting a flu vaccine, talk to your doctor if:

• You ever had a serious allergic reaction to eggs or to a previous dose of influenza vaccine.
• You have had Guillain-Barré syndrome.

The yearly immunization rate is typically low for people younger than 65 who are at high risk of developing the flu. All people in high-risk groups and those who could transmit the virus to them because of regular contact are strongly encouraged to get the flu vaccine.

Almost every community has a program that offers flu vaccines at low cost during the flu season. You also can get a flu vaccine during a routine visit to a doctor or pharmacy. Many health clinics have set hours at the start of the flu season for people to get flu vaccines without needing to make an appointment.

Flu Vaccines: Should I Get a Flu Vaccine?

Although antiviral medicines sometimes prevent the flu, they do not work in the same way as a yearly immunization and should not replace a flu shot or dose of the nasal spray vaccine.