Clostridioides Difficile (C. diff) Toxins Test

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Test Overview

Clostridioides difficile (C. diff) are bacteria that live in your large intestine, or colon, all the time. They usually don't cause problems. But sometimes, something causes the bacteria to grow. When there are too many of them, they release harmful substances called toxins.

When the toxins are released, the colon becomes irritated and swollen. This problem is called C. diff colitis.

C. diff can be passed from person to person. But the infection is most common in people who take antibiotics or have taken them recently. Antibiotics are drugs used to kill bacteria that cause infection. But they also can destroy some of the normal "good" bacteria in the colon that keep C. diff from growing and releasing toxins.

C. diff is also common in older people who are in hospitals and nursing homes and in people who are getting chemotherapy for cancer.

The C. diff toxins test looks at a stool sample to see if those toxins are present. A positive result means you need treatment for colitis.

Why It Is Done

The test is done to see if diarrhea that won't go away was caused by Clostridioides difficile (C. diff) toxins.

How To Prepare

Tell your doctor if you have recently taken antibiotics.

How It Is Done

Stool samples can be collected at home. Or you may need to go to your doctor's office, a medical clinic, or the hospital. If you collect the sample at home, you may be given a special container.

You may need to collect more than one sample. Follow the same steps for each sample.

To collect the sample:

  • Urinate before you collect the stool. That way, you won't get any urine in the stool sample. Do not urinate while you pass the stool.
  • Wash your hands with soap and clean, running water before and after you collect the sample. Do not use an alcohol-based hand sanitizer instead of washing your hands. Sanitizer will not kill C. diff.
  • Put on gloves before handling your stool. Stool can contain germs that spread infection. Wash your hands before you put on your gloves and after you take them off.
  • Pass stool (but no urine) into a dry container. You may be given a plastic basin that you can place under the toilet seat to catch the stool.
    • For diarrhea, a large plastic bag taped to the toilet seat may make the collection process easier. The bag is then placed in a plastic container.
    • Do not collect the sample from the toilet bowl.
    • Do not mix toilet paper, water, or soap with the sample.
  • Place the lid on the container. Label it with your name, your doctor's name, and the date the stool was collected.

Take the sample to your doctor's office or the lab as soon as you can. You may need to take your sample to the lab within a certain time, usually within 30 minutes or less of collecting it. Tell your doctor if you think you may have trouble getting the sample to the lab on time.

Samples from babies and young children may be taken from diapers (if the stool does not have urine mixed with it). Or a narrow tube may be put into the baby's rectum while you hold the baby on your lap.

How It Feels

This test usually doesn't cause any pain or discomfort.


There is a chance you can spread the infection if you don't wash your hands well when you collect the stool sample.


There are several types of tests for this toxin. Depending on the test used, results may take several hours or a day or two.

C. diff toxins in stool

Normal (negative)

The stool sample does not contain C. diff toxin.

Abnormal (positive)

The stool sample contains C. diff toxin.


Current as of: June 12, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.