CYP2B6: Genetic variants impacting medication reactions

The CYP2B6 enzyme is part of the body’s first line of defense in detoxifying and breaking down certain substances. It is one in the family of CYP450 enzymes, and CYP2B6 is important for metabolizing several medications.

CYP2B6, genetics, and medication interactions:

Genetic variants in the CYP2B6 gene cause large variations in how the enzyme works. For some people, genetic variants cause significant decreases in enzyme function, while others may have faster enzyme function.[ref]

Drugs metabolized by CYP2B6 include:[ref][ref]

    • methadone
    • bupropion
    • ketamine
    • cyclophosphamide
    • artemisinin
  • efavirenz – HIV medication
  • nicotine (along with CYP2A6)[ref]
  • sertraline – Zoloft (along with other CYP enzymes)[ref]
  • estrone and 17beta-estradiol (along with other CYP enzymes)[ref]

In general, CYP2B6 enzyme function is a little higher in women than men.[ref]

What does CYP2B6 do besides break down medications?

An animal study in mice shows that reduced CYP2B6 function causes problems with metabolizing corn oil.

Mice with reduced CYP2B6 function ended up becoming more obese and having higher triglycerides and cholesterol (compared to normal mice) when fed a bunch of corn oil.[ref] Keep in mind that this is an animal study… I’m unable to find any research on humans with lower CYP2B6 and dietary interactions.

CYP2B6 Genetic Variants:

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The CYP2B6 enzyme metabolizes organophosphates at lower concentrations, such as from normal exposure to pesticide residue.[ref]

Check your genetic variants for rs3745274 G516T (23andMe v.4; AncestryDNA):

  • T/T: CYP2B6*6, decreased activity[ref][ref] may need a lower dose of efavirenz (HIV medication)[ref][ref] slower clearance of ketamine[ref]
  • G/T: somewhat decreased activity
  • G/G: typical

Members: Your genotype for rs3745274 is .

Check your genetic data for rs2279343 K262R (23andMe v5):

  • G/G CYP2B6*6, decreased activity[ref][ref] may need a lower dose of efavirenz (HIV medication)[ref][ref]; slower clearance of ketamine[ref]
  • A/G: somewhat decreased activity
  • A/A: typical; better response to quitting smoking[ref]

Members: Your genotype for rs2279343 is .

Check your genetic data for rs28399499 C983T (23andMe v4, v5; AncestryDNA):

  • C/C: significantly reduced enzyme activity; 3x increased risk of adverse drug reactions with efavirenz (may need a lower dose)[ref][ref]
  • C/T: reduced enzyme activity
  • T/T: typical

Members: Your genotype for rs28399499 is .

Check your genetic data for rs3211371 T1459C (23andMe v4):

  • T/T: reduced function, especially in women[ref]
  • C/T: reduced function, especially in women
  • C/C: typical

Members: Your genotype for rs3211371 is .



If you are taking a medication that is metabolized using CYP2B6, talk with your doctor or pharmacist if you have questions about the dosage.

If you are a slower CYP2B6 metabolizer, interactions with other medications may become more important. For example, clopidogrel (Plavix) also inhibits the CYP2B6 enzyme.[ref]

Curcumin, a popular anti-inflammatory supplement, is an inhibitor of CYPB6.[ref] If you have variants that slow down CYP2B6, taking a curcumin supplement along with a medication metabolized by CYP2B6 may impact the way the medication works.

Astragalus is another natural supplement that inhibits CYP2B6.[ref]

Recap of your genes:

Gene RS ID Risk Allele YOU Notes about the Risk Allele:
CYP2B6 rs3745274 T CYP2B6*6, decreased activity
CYP2B6 rs2279343 G CYP2B6*6, decreased activity
CYP2B6 rs28399499 C reduced enzyme activity
CYP2B6 rs3211371 T reduced enzyme activity

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About the Author:
Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering and an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.