Your doctor will conduct a physical exam, look for signs and symptoms of influenza, including H1N1 flu (swine flu), and possibly order a test that detects influenza viruses such as H1N1.

There are several tests used to diagnose influenza, but not everyone who has the flu needs to be tested. Your doctor may diagnose you with influenza based on your signs and symptoms. In most cases, knowing that someone has the flu doesn't change the treatment plan. Doctors are more likely to use a test to diagnose flu if:

  • You're already in the hospital
  • You're at high risk of complications from the flu
  • You live with someone who is at greater risk of flu complications

Your doctor may also use a test to determine whether a flu virus is the cause of your symptoms, or if you have or are showing signs of another problem besides the flu, such as:

  • Heart problems, such as heart failure or an infection of the heart muscle
  • Lung and breathing problems, such as asthma or pneumonia
  • Brain and nervous system problems, such as encephalopathy or encephalitis
  • Septic shock or organ failure

In some cases, your doctor may suggest that you be tested for influenza. He or she may use various tests to diagnose influenza. Polymerase chain reaction (PCR) testing is becoming more common in many hospitals and labs. This test may be done while you're in your doctor's office or in the hospital. PCR testing is more sensitive than other tests and may be able to identify the influenza strain.

During the COVID-19 pandemic, it's possible to have a test to diagnose both influenza and COVID-19. It's possible to have both COVID-19 and influenza at the same time.


Most people with flu, including H1N1 flu (swine flu), require only symptom relief. Supportive care such as drinking liquids, taking pain relievers for fever and headache, and resting may be helpful. If you have a chronic respiratory disease, your doctor may prescribe additional medications to help relieve your symptoms.

Antiviral drugs are sometimes prescribed within the first day or two of symptoms. They can reduce the severity of symptoms and possibly the risk of complications. The U.S. Food and Drug Administration has approved these four drugs:

  • Oseltamivir (Tamiflu)
  • Zanamivir (Relenza)
  • Peramivir (Rapivab)
  • Baloxavir (Xofluza)

But flu viruses can develop resistance to these drugs.

To make development of resistance less likely and maintain supplies of these drugs for those who need them most, doctors reserve antivirals for people at high risk of complications and those who are in close contact with people who have high risk of complications.

People at higher risk of flu complications include people who:

  • Are in a hospital, nursing home or other long-term care facility.
  • Are younger than 5 years of age, particularly children younger than 2 years.
  • Are 65 years old or older.
  • Are pregnant or within two weeks of delivery, including women who have had pregnancy loss.
  • Are younger than 19 years of age and are receiving long-term aspirin therapy. Using aspirin during a viral illness increases the risk of developing Reye's syndrome, a rare but potentially life-threatening condition, in these individuals.
  • Have a body mass index above 40, which is defined as morbid obesity.
  • Have certain chronic medical conditions, such as asthma, emphysema, heart disease, diabetes, neuromuscular disease, or kidney, liver or blood disease.
  • Are immunosuppressed due to certain medications or HIV.
  • Are of American Indian or Alaska Native heritage.

Lifestyle and home remedies

If you develop any type of flu, these measures may help ease your symptoms:

  • Drink plenty of liquids. Choose water, juice and warm soups to prevent dehydration.
  • Rest. Get more sleep to help your immune system fight infection.
  • Consider pain relievers. Use an over-the-counter pain reliever, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others).

    Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

If you have the flu, you can give it to others. Stay home for at least 24 hours after your fever is gone.