(CNN)Is your blood type A, B, a combination of the two or something else?
You don't know, you say? Many people don't know their blood type. In fact, only 66% of Americans reported knowing their blood type, according to a 2019 CBS News poll.
Those letters (and pluses and minuses) can be crucial information in an emergency, and there are simple but accurate ways to find out.
Most blood types are only compatible with a handful of others, according to Dr. Dayand Borge, Divisional Chief Medical Officer at the American Red Cross.
Accidental Incompatible blood transfusions, while rare, can be dangerous, Borge said.
Luckily, there are easy ways to find out your blood type.
Ask your parents or doctor
Before you go out of your way to try any of the other methods, check with your parents first. They may know or have old health records that include your blood type. You can also reach out to your healthcare provider, who may have that information on file.
Next time you go in to get your blood drawn, ask to know your blood type. If you've had blood drawn in the past, you can call the lab to see if they have the information. To request a blood test, visit your healthcare provider or a local health clinic.
At-home blood test
You can also purchase an at-home blood test online and have it shipped to your door. The kit comes with a needle and a testing card to drop your blood on. For many at-home tests, results take only minutes.
When you donate blood, the blood goes through multiple tests, including blood type. After you've donated with the Red Cross, you're given a blood donor card which will give you access to your blood type when they test it. This takes a few days and is free. If you've donated in the past, you may be able to check your blood type on their website.
For those squeamish of needles, a saliva test can help you determine your blood type without having to draw blood.
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About 80% of people secrete the same antigens that are in their blood as in their saliva, according to a study published in the Journal of Clinical & Diagnostic Research.
This means that the test is effective for most, but not everyone. These tests can be found online and cost more than the traditional, at-home blood tests.