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How Many Days Can You Test Positive for the Flu?

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Your throat is on fire, your nose won’t stop running and you feel miserable. If you’re experiencing these symptoms, you might have the flu. Influenza is a virus that infects your nose, throat and respiratory tract. It’s contagious, often spreading rapidly throughout fall and winter.

The flu can have dangerous or even deadly consequences. When you’re sick with any contagious virus, staying home and recovering before spending time around others again is best. But what happens when you start feeling better? How many days can you test positive for the flu?

Here is what you need to know about this highly contagious virus and how flu tests work.

Understanding Flu Testing

Flu tests come in different forms, but they all require a respiratory sample — a health professional swabs your nose or throat to collect the sample and send it off for testing. Take a closer look at some of the different types of flu tests and their pros and cons.

Rapid Influenza Diagnostic Tests (RIDTs)

A rapid influenza diagnostic test (RIDT) — also known as an antigen test — checks for influenza antigens, which are the molecules that trigger your immune system to start fighting off the flu. These rapid tests, also known as antigen tests, can quickly identify influenza types A and B. RIDTs use nasal swab samples to detect the virus.

RIDTs can produce false negatives, meaning you may still have the flu even if your rapid antigen test is negative. Rapid flu tests are convenient but may not produce accurate results.

Molecular Tests (PCR)

Molecular tests for influenza — such as polymerase chain reaction (PCR) tests — are a bit more sophisticated. They detect the flu virus’s genetic material in your body within 30 minutes.

Your results are more accurate when opting for a molecular test over a rapid one. To get a sample for a PCR test, you need a deep nasal swab that reaches the back of your throat.

Flu Symptom Duration: What to Expect

You’ll likely feel awful once you’ve contracted the flu. You might be wondering when the worst symptoms will finally go away. While everyone is different, there are general timelines you can expect after coming down with the flu.

Flu Onset

Flu symptoms typically show up two to four days after you’ve come in contact with the virus. It can take as long as seven days for some people, but this is rare. You may notice mild fatigue, chills, aches and sinus symptoms during this time.

Duration of Flu Symptoms

After contracting the flu, you can expect your symptoms to last at least four to seven days. You may feel tired and drained for a few weeks afterward as well.

Contagiousness and Transmission

You’re contagious with the flu for up to four days after you notice symptoms, and you might transmit the flu without knowing it a day or two before your symptoms begin. After five to seven days, you can safely assume you’re no longer contagious.

To prevent spreading the flu to another person, you should avoid close contact with others during the contagious period. If you can’t limit your in-person contact, masking is a good precaution. Wearing a mask traps respiratory droplets instead of allowing them to pass through the air, which is how the flu spreads.

Always practice frequent hand-washing during cold and flu season. Flu tests may not detect your infection immediately, and hand-washing is the best way to prevent the spread of contagious illness.

Flu Test Positivity Timeline: How Long Do You Test Positive?

How many days can you test positive for the flu after you’ve come down with the illness? You might be confused if you’re still testing positive after feeling better. You want to return to normal life, but how do you know when that’s possible?

Rapid tests are most accurate within three to four days of symptom onset. This means a false negative is possible any time after four days of experiencing flu symptoms.

On the other hand, there’s some evidence that PCR tests can come back negative up to seven days after symptom onset. Most health care professionals consider PCR flu tests more accurate and sensitive when detecting the flu virus.

Different tests may produce different results. It all depends on how long your body takes to fight off the flu virus and eliminate flu antigens circulating in your blood.

Recovery and Returning to Normal Activities

Rest and hydration are two of the biggest keys to flu recovery. If you want to get better quickly, spend plenty of time sleeping and resting your body. Ensure you drink plenty of water and electrolytes to nourish your body.

If you try to return to your normal activities too soon, you can prolong your flu symptoms. This is a lose-lose situation, as you risk exposing others to the flu and worsening your illness.

Wait until you feel fully rested and recovered before engaging in strenuous activity. If you have mild to moderate flu with no hospitalizations, you’ll probably be back on your feet in a week or two.

Getting Medical Clearance

It’s best to consult a health care professional when you want to return to work, school and other activities. They can evaluate your symptoms and determine whether you’re well enough to return to normal life. This is especially important if you notice new or worsening symptoms or if you have other health complications.

Get Tested for the Flu at AdventHealth Centra Care

There are different options for flu testing, and you may test positive or negative depending on which test you receive and how many days you’ve experienced symptoms. Understanding how many days you can test positive for the flu is important as it will help you avoid exposing others to the virus before fully recovering.

Seeking medical guidance is key for any case of the flu. At AdventHealth Centra Care, we offer quality urgent care and medical advice for contagious illnesses like the flu. Schedule an appointment or walk in for flu testing at a location near you.

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