Healthcare professionals usually test for whooping cough (pertussis) by taking a sample of mucus from deep inside the nose or throat and checking it in the lab, often with a PCR test and/or culture, sometimes along with blood tests and a chest X‑ray to look for complications like pneumonia.

What whooping cough tests look for

Whooping cough is caused by the bacteria Bordetella pertussis , so the main goal of testing is to find either the bacteria itself or its genetic material.

Because early symptoms can look like a common cold, lab tests help confirm the diagnosis, especially in babies, pregnant people, and others at higher risk.

Main diagnostic tests

  • Nasopharyngeal swab or wash (the classic test)
    • A long, thin swab is gently passed through a nostril to the back of the nose/throat (nasopharynx), rotated for a few seconds, then removed.
* Sometimes saline is squirted into the nose and then suctioned back out as a “wash” instead of using a swab.

* This sample is then tested in the lab for _Bordetella pertussis_.
  • PCR test (most common modern test)
    • The mucus sample from the nose/throat is analyzed using PCR (polymerase chain reaction) to detect the bacteria’s DNA.
* It is most accurate in the first 2–3 weeks after the cough starts and can give results within hours.
  • Culture test (growing the bacteria)
    • The same type of swab sample is placed on special media to see if Bordetella pertussis will grow.
* It can take several days up to a week for results, but a positive culture is very specific for whooping cough.
  • Blood tests and chest X‑ray (supporting tests)
    • Blood tests can show signs of infection or, in some cases, antibodies, but they are not specific enough on their own to diagnose pertussis.
* A chest X‑ray may be done if the doctor is worried about pneumonia or other lung problems from the infection.

When and why they test

  • Doctors usually consider whooping cough testing when someone has:
    • A cough lasting more than a week or two, especially with severe coughing fits, vomiting after coughing, or the classic “whoop” sound.
* Close contact with a confirmed pertussis case, particularly if they are an infant, pregnant, or have a weak immune system.
  • Timing matters:
    • Swab‑based PCR and culture are most useful in the first few weeks of illness, before or early in the “whooping” phase.
* Later in the illness, PCR and culture may turn negative even if the person still has symptoms, so the diagnosis may rely more on history, exam, and sometimes blood tests.

What the test experience feels like

  • The nasopharyngeal swab can feel strange and briefly uncomfortable, like a strong tickle or pressure high in the nose, and it may make eyes water or cause a brief urge to cough or sneeze.
  • The procedure is quick, usually taking just a few seconds for the swab itself, and then you are done while the lab processes the sample.

If you or a child has a long‑lasting or severe cough, breathing pauses, or any blue discoloration around the lips or face, emergency medical care is needed, and testing for pertussis is often part of that evaluation.

TL;DR: They test for whooping cough mainly by swabbing deep inside the nose/throat and running PCR and/or culture on that mucus, sometimes supported by blood tests and a chest X‑ray, with timing in the first weeks of illness giving the clearest results.

Information gathered from public forums or data available on the internet and portrayed here.