Thanks to antiviral medications that can shorten the flu’s duration, getting a positive flu result may help you get treatments more effectively.
Fortunately, a number of tests are available for the flu, many of which can provide rapid results.
The next time you have symptoms such as a fever, fatigue, body aches, and sore throat, here’s a rundown of how fast you can expect to find out if your symptoms mean you have the flu.
Getting a flu test isn’t usually a time-consuming experience. Your healthcare professional may use one of several approaches to collect a specimen. These include:
- Deep nasal swab. This testing method involves inserting a swab about one inch into the nostril. It doesn’t require inserting as deeply as a nasopharyngeal swab (see below).
- Nasopharyngeal or nasal aspirate. A less commonly used method, this involves using a special suction catcher to suction mucus for sample collection. When the suction catheter is very far in the back of the throat, doctors call this nasopharyngeal aspirate.
- Nasopharyngeal swab. For this test, you’ll be asked to tilt your head back, and a healthcare provider will swab both nostrils. The swab should be inserted to where there’s an equal distance between the nostril and the outer ear opening.
- Throat or nasal swab. This testing method involves using both a nasal swab as well as a throat swab that reaches back into the tonsil area of the throat.
Each of these testing methods usually takes no more than 1 minute to perform. It’s waiting for your results that can prove longer.
Innovations in flu testing mean that you may be able to obtain results as fast as 10 to 15 minutes. Doctors call these “rapid” tests. According to the
With these and other flu tests, it’s still possible to get a false negative. A doctor should take your symptoms into account as well as if you’ve been around anyone who was recently diagnosed with the flu.
A variety of influenza virus test types exist. Some test for the presence of the flu virus, while others test your body’s response to the virus. Examples, with their result times, include the following:
- Immunofluorescence. This testing type typically involves using a special microscope to identify flu antigens (antibodies to the flu). While a rapid test takes about
15 minutestill the result is available, most tests take about 2 to 4 hours to obtain results.
- Rapid influenza diagnostic tests (RIDTs). This type tests for the presence of viral antigens, which the body produces in response to the presence of the flu virus. However, these tests aren’t as sensitive (accurate) for the flu as others and can often read a false negative result. They also may not mean you have an active form of the flu. A person can get results within 10 to 15 minutes.
- Rapid molecular assays. This is a rapid test designed to identify influenza nucleic acids (genetic material). According to the
CDC, the test is highly sensitive and specific for the flu. The tests can usually provide you with results in 15 to 30 minutes. Doctors call these test types point-of-care testing (POCT), which means they can be performed at the bedside without sending them to a laboratory.
- Reverse transcription-polymerase chain reaction (RT-PCR). These testing types can also detect flu genetic material to highly accurate levels. The tests may also help determine if you have influenza type A or type B. Getting results for these tests can take
between 45 minutes to upwards of 3 hours.
If you see a doctor because you think you may have the flu, you can ask them what testing type they use.
Generally speaking, if your flu test is positive, you have the flu. If your flu test is negative, it’s possible the test doesn’t recognize the flu strain type that you have. The person performing your flu test also may not have collected enough material to accurately detect the flu.
According to the American Association of Clinical Chemistry, rapid antigen tests are about 50 to 70 percent accurate, although the Food and Drug Administration (FDA) has required more recent tests to make changes to improve their results.
Molecular tests are anywhere from 66 to 100 percent accurate. The results and accuracy depend upon what test type you use.
Testing specimens are most likely to be accurate when they’re measured within
Less is known about flu tests’ abilities to detect the flu in asymptomatic patients because most people seek the tests when they aren’t feeling well.
Flu tests are available at most doctors’ offices, urgent care settings, and hospitals.
Rapid flu tests are usually less costly than laboratory-based tests. According to Becker’s Hospital Review, rapid tests cost about $5 to $10, while a laboratory test can cost $200 or more.
You may wish to contact a facility where you’re seeking testing to ensure they have flu tests available, especially if you’re in flu season, which usually takes place in the late fall to winter.
Flu tests can provide rapid results that are becoming increasingly more accurate. Doctors may select tests based on availability and accuracy.
It’s important to remember that you’re more likely to have a false negative test than a false positive one. As a result, a doctor may treat your symptoms as if you have the flu, even when your test is negative.