Here’s a dirty little secret: not all prescription drugs will work for you.

Ok, that isn’t really a secret. Anyone who has ever gotten a prescription from their doctor knows it is usually accompanied by “Let’s see if the medication will work for you”. C’mon, Doc. Can’t we do better than just guessing?

Genes play a huge role in whether a medication will work for you.  Your gut microbiome also affects medications, but the major factor is usually genetics.  Pharmaceutical companies know this. They have spent millions of dollar researching the interactions between genetic variants and their medications.  GlaxoClineSmith, a huge drug company, has partnered with 23andMe for access to their data for research studies. (You have to opt-in to research surveys on 23andMe for this to include your data.)


Keep in mind that everything that I’m including here is for educational purposes only! Decisions on medications should always be made with your doctor’s advice. Everything below has links to references that you can print out and take to your doctor as well.


Below are examples of genetic variants (found in 23 and Me or AncestryDNA data) that have been tied to how well prescription medications will work for you.  This is not a complete list… but hopefully it will get you started on learning more about how your genes interact with medications.

Rev-Erb-alpha gene:

Check your 23andMe results forrs2314339 (v4, v5):

  • TT: more likely to be a lithium non-responder for bipolar disorder[ref]
  • CT: more likely to be a lithium non-responder for bipolar disorder
  • CC: normal risk of being a lithium non-responder

CYP2C19 gene:

Check your 23andMe results for rs12248560 (v4, v5) CYP2C19*17:

  • TT: ultrafast metabolizer of certain medications including omeprazole (Prilosec)[ref], citalopram (Celexa) and escitalopram (Lexapro)[ref] plavix
  • CT: fast metabolizer of certain medications including omeprazole (Prilosec), citalopram (Celexa) and escitalopram (Lexapro)
  • CC: normal / common type

Check your 23andMe results for rs28399504 (v4, v5) CYP2C19*4:

  • GG: Poor metabolizer of medications such as omeprazole, citalopram and escitalopram[ref], and Plavix[ref]
  • AG: Slow metabolizer of medications such as omeprazole and Plavix
  • AA: normal /most common genotype

Check your 23andMe results for rs4244285 (v4, v5) CYP2C19*2:

  • AA: Poor metabolizer of medications such as omeprazole, citalopram and escitalopram[ref], and Plavix[ref]
  • AG:  Slow metabolizer of medications such as omeprazole and Plavix
  • GG: normal / most common type

SLCO1B1 gene:

Check your 23andMe results for rs4149056 (v4, v5):

  • CC: a significant increase in the risk of myopathy with statin use[ref] reduced methotrexate clearance[ref] altered erythromycin metabolism[ref]
  • CT: increased risk of myopathy with statin use, reduced methotrexate clearance, altered erythromycin metabolism
  • TT: normal / most common type

CYP3A4 Gene Variants:

CYP3A4 metabolizes about half the drugs on the market.  So if you carry one of the variants that decrease enzyme function, please check this list for drug interactions and be sure to talk with your doctor about prescription meds.

Check your 23andMe results for rs4987161 (v4, v5):

  • GG: CYP3A4*17, decreased function of enzyme, [ref] [ref]
  • AG: carrier of one CYP3A4*17 allele
  • AA: normal

Check your 23andMe results for rs4986909 (v4 only):

  • AA: CYP3A4*13, decreased function of the enzyme, [ref]
  • AG: carrier of one CYP3A4*13 allele
  • GG: normal

Check your 23andMe results for rs2740574 (v4,v5):

  • CC: CYP3A4*1B, decreased function of the enzyme [ref]
  • CT: carrier of one CYP3A4*1B allele
  • TT: normal

Check your 23andMe results for rs4986910 (v4, v5):

  • GG: CYP3A4*3, decreased function
  • AG: carrier of one CYP3A4*3 allele
  • AA: normal

Check your 23andMe results for rs4986907 (v4, v5):

  • TT: CYP3A4*15A, decreased function
  • CT: carrier of one CYP3A4*15A allele
  • CC: normal

CYP4F2 Gene:

Check your 23andMe results for rs2108622  (v4, v5) — also known as  Val433Met or CYP4F2*3

  • TT: reduced CYP4F2 function, possibly need higher Warfarin dosages[ref][ref][ref], somewhat increased risk of stroke[ref][ref]
  • CT: reduced CYP4F2 function, possibly need higher Warfarin dosages[ref][ref], somewhat increased risk of stroke[ref][ref]
  • CC: normal

COMT Gene:

Check your 23andMe results for rs4680 (v.4 and v.5):

  • GG: (Val/Val) higher COMT activity, better response to modafinil[ref] increased likelihood of remission with SSRI[ref] may need higher dose of opioids for pain[ref]
  • AG: intermediate COMT activity
  • AA: (Met/Met) lower COMT activity, not as much response to modafinil, may need lower dose of opioids for pain[ref]

SLC22A1 Gene:

Check your 23andMe results for rs622342 (v4, v5):

  • CC: decreased metformin response[ref][ref]
  • AC: decreased metformin response[ref][ref]
  • AA: normal

Check your 23andMe results for rs628031 (v4, v5):

  • GG: possibly decreased metformin response[ref]
  • AG: possibly decreased metformin response
  • AA: normal
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