Dextromethorphan also known as the “DM” found in many cough and cold products is metabolized and inactivated in the body by an enzyme called CYP2D6.

The normal “half-life” or time it takes for the level of DM in a person’s body to be reduced by half is 2 to 4 hours. However, in people who are poor metabolizers (make zero or close to zero CYP2D6 enzyme), the half-life is 24 hours.

It takes approximately 5 half-lives to rid the body of 95% of a medication. This means CYP2D6 poor metabolizers will take ~5 days to get rid of a single dose of DM!!!

If DM makes you feel groggy, out of it, disconnected or “not right” and your best friend has no problem with the medication, genetics are likely the reason. You may be a poor or intermediate metabolizer of CYP2D6. A pharmacogenomic test can give you answers.