When you take a medicine (or drug), your body needs to find a way to use it. Some proteins in your body break down (or metabolize) medicines. Breaking down a medicine can make it more active or less active, depending on what kind of medicine you are taking. If your body breaks down a medicine too quickly or too slowly, this may make the medicine not work as well. It may also cause a side effect.


The CYP2D6 gene gives instructions to your body about how to make a protein. It is the job of the CYP2D6 protein to break down certain medicines.  Some of these medicines are:

  • Some medicines that help with your mood.
  • Some medicines that are used to treat pain.
  • Metoclopramide: Used to treat slow digestion because of diabetes mellitus or gastroesophageal reflux disease (GERD).
  • Metoprolol: Used to treat some heart conditions or high blood pressure.
  • Ondansetron: Used to treat nausea or vomiting.


These are the medicines that we know of right now that are impacted by CYP2D6 gene test results. Medical experts keep finding new data about which medicines are affected by gene test results.


By testing your DNA, we can find DNA differences. This can help us to see how well the proteins in your body work to break down certain medicines. 

The results of your CYP2D6 gene test put you into 1 of 4 groups:

  • Ultrarapid metabolizer: People in this group may have increased activity of CYP2D6 proteins.
  • Normal metabolizer: People in this group are likely to have normal working CYP2D6 proteins.
  • Intermediate metabolizer: People in this group may have reduced activity of CYP2D6 proteins. 
  • Poor metabolizer: People in this group may have very little or no active CYP2D6 protein. 


The results of this test can help your doctor choose the right medicine and dose for you.

Colorado Center for Personalized Medicine

University of Colorado Anschutz Medical Campus

CU Anschutz

Anschutz Health Sciences Building

1890 N Revere Ct

Mailstop F563

Aurora, CO 80045

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