By Scott T. Roethle, MD, FASA. Board certified, American Board of Anesthesiology.

Did you know that your genes can affect how you respond to certain medications and whether you experience adverse side effects? For example, about 10 percent of people will receive little or no pain relief from codeine because their genetics mean that their bodies don’t properly metabolize codeine into morphine[i].

For the 50 million Americans who experience chronic pain, it can be incredibly frustrating not to find adequate relief from prescription medication or experience adverse effects when trying a new prescription option. In the past, doctors and patients alike had to rely on trial and error to find out which medication and dosage would work best. Now, patients can access a simple genetic test which could tell them which pain medication might work best for them.

Genes determine your medication response

Your body has thousands of genes that you inherited from your parents. Your genes determine which characteristics you have, such as your eye color, hair color, or blood type. Some genes are responsible for how your body may absorb and/or respond to certain medications. This includes both prescription and over-the-counter medications.

Pharmacogenetic (PGx) testing is a type of genetic test that assesses how likely someone is to respond effectively, or to have an adverse response, to a certain drug. Recent advances in pharmacogenetic science have shown that 95 percent of a person’s response to a drug is determined by genetics.[ii] This means that two people can take the same dose of the same drug but respond in very different ways.

How does PGx work?

A PGx test uses a small saliva sample to analyze your DNA and look for the genetic variants that are associated with variable response to certain medications. The results of a PGx test, combined with other clinical and diagnostic information, can be very valuable and may allow physicians to create individually tailored treatment plans for their patients. Patients, particularly those taking multiple medications, could benefit from more effective treatments and potentially fewer adverse reactions thanks to PGx testing.

Fortunately, PGx testing is widely available and can be done from the comfort of your home. There are multiple companies who will send you a kit that allows you to mail in your saliva sample. From there, you’ll receive the results and even a consultation with a clinician.

About elicity: elicity is an online health platform offering easy, at-home access to medically actionable pharmacogenomics testing (PGx) combined with on-demand physician support and guidance. elicity is powered by InTeleLabs, a telehealth and personalized medicine company. To find out more about elicity and PGx testing, visit

[i] Dean L. Codeine Therapy and CYP2D6 Genotype. 2012 Sep 20 [Updated 2017 Mar 16]. In: Pratt V, McLeod H, Rubinstein W, et al., editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012-. Available from:

[ii] Kalow W, Tang BK, Endrenyi L. Hypothesis: comparisons of inter- and intra-individual variations can substitute for twin studies in drug research. Pharmacogenetics. 1998;8(4):283–289.