CYP2D6 is a liver enzyme that handles many common medicines, from codeine and tramadol to several antidepressants and antipsychotics. People can carry missing, extra or slow copies of the gene, which is why it matters so much for dosing and why the usual genetic studies barely see it.
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CPIC, the international group that writes gene-based prescribing guidelines, rates how strong the evidence is for each gene and medicine, from A (strong enough to change the prescription) to D (weak or conflicting). Every rating is shown, the weak ones included, so you can see where the evidence stops.
amitriptyline· level A: strong enough to change the prescription
atomoxetine· level A: strong enough to change the prescription
codeine· level A: strong enough to change the prescription
nortriptyline· level A: strong enough to change the prescription
ondansetron· level A: strong enough to change the prescription
paroxetine· level A: strong enough to change the prescription
pitolisant· level A: strong enough to change the prescription (provisional)
tamoxifen· level A: strong enough to change the prescription
tramadol· level A: strong enough to change the prescription
tropisetron· level A: strong enough to change the prescription
vortioxetine· level A: strong enough to change the prescription
eliglustat· level A/B: strong enough to change the prescription (provisional)
oliceridine· level A/B: strong enough to change the prescription (provisional)
pimozide· level A/B: strong enough to change the prescription (provisional)
tetrabenazine· level A/B: strong enough to change the prescription (provisional)
aripiprazole· level B: enough to change the prescription in some cases (provisional)
clomipramine· level B: enough to change the prescription in some cases
desipramine· level B: enough to change the prescription in some cases
doxepin· level B: enough to change the prescription in some cases
fluvoxamine· level B: enough to change the prescription in some cases
hydrocodone· level B: enough to change the prescription in some cases
imipramine· level B: enough to change the prescription in some cases
metoprolol· level B: enough to change the prescription in some cases
risperidone· level B: enough to change the prescription in some cases (provisional)
trimipramine· level B: enough to change the prescription in some cases
venlafaxine· level B: enough to change the prescription in some cases
amoxapine· level B/C: not yet enough to change the prescription (provisional)
amphetamine· level B/C: not yet enough to change the prescription (provisional)
aripiprazole lauroxil· level B/C: not yet enough to change the prescription (provisional)
brexpiprazole· level B/C: not yet enough to change the prescription (provisional)
cevimeline· level B/C: not yet enough to change the prescription (provisional)
clozapine· level B/C: not yet enough to change the prescription (provisional)
deutetrabenazine· level B/C: not yet enough to change the prescription (provisional)
dextromethorphan· level B/C: not yet enough to change the prescription (provisional)
donepezil· level B/C: not yet enough to change the prescription (provisional)
flecainide· level B/C: not yet enough to change the prescription (provisional)
gefitinib· level B/C: not yet enough to change the prescription (provisional)
haloperidol· level B/C: not yet enough to change the prescription (provisional)
iloperidone· level B/C: not yet enough to change the prescription (provisional)
labetalol· level B/C: not yet enough to change the prescription (provisional)
lofexidine· level B/C: not yet enough to change the prescription (provisional)
meclizine· level B/C: not yet enough to change the prescription (provisional)
metoclopramide· level B/C: not yet enough to change the prescription (provisional)
mirabegron· level B/C: not yet enough to change the prescription (provisional)
mirtazapine· level B/C: not yet enough to change the prescription (provisional)
perphenazine· level B/C: not yet enough to change the prescription (provisional)
propafenone· level B/C: not yet enough to change the prescription (provisional)
protriptyline· level B/C: not yet enough to change the prescription (provisional)
tamsulosin· level B/C: not yet enough to change the prescription (provisional)
thioridazine· level B/C: not yet enough to change the prescription (provisional)
timolol· level B/C: not yet enough to change the prescription (provisional)
valbenazine· level B/C: not yet enough to change the prescription (provisional)
zuclopenthixol· level B/C: not yet enough to change the prescription (provisional)
acebutolol· level C: not enough to change the prescription
betaxolol· level C: not enough to change the prescription
bisoprolol· level C: not enough to change the prescription
carvedilol· level C: not enough to change the prescription
citalopram· level C: not enough to change the prescription
darifenacin· level C: not enough to change the prescription (provisional)
dolasetron· level C: not enough to change the prescription
duloxetine· level C: not enough to change the prescription
escitalopram· level C: not enough to change the prescription
fesoterodine· level C: not enough to change the prescription (provisional)
flibanserin· level C: not enough to change the prescription (provisional)
fluoxetine· level C: not enough to change the prescription
galantamine· level C: not enough to change the prescription (provisional)
methadone· level C: not enough to change the prescription
methylphenidate· level C: not enough to change the prescription (provisional)
modafinil· level C: not enough to change the prescription (provisional)
nebivolol· level C: not enough to change the prescription
oxycodone· level C: not enough to change the prescription
palonosetron· level C: not enough to change the prescription
propranolol· level C: not enough to change the prescription
quinidine· level C: not enough to change the prescription (provisional)
quinine· level C: not enough to change the prescription (provisional)
ramosetron· level C: not enough to change the prescription
sertraline· level C: not enough to change the prescription
terbinafine· level C: not enough to change the prescription (provisional)
tolterodine· level C: not enough to change the prescription (provisional)
Source: CPIC (Clinical Pharmacogenetics Implementation Consortium), public domain (CC0), copy kept on this site and refreshed weekly.
US drug labels that name CYP2D6 (76)
The FDA keeps a list of medicine labels that mention a gene. These are the ones that name CYP2D6. Where this site has a page on the medicine, the name links to it; otherwise it opens the label on DailyMed. A label naming a gene does not always mean a test or a dose change: for many it is one line about how the body clears the drug.
No published variants sit in CYP2D6 on this site; its effect on medicines is on the drug pages above.
Questions about CYP2D6
Why are there no CYP2D6 variants on this page?
Because the large studies this site collects from use chips that cannot count whole copies of a gene, and CYP2D6 differs between people mostly by missing or extra copies. Its importance shows up through the drug pages instead.
What is a CYP2D6 poor or ultrarapid metabolizer?
A poor metabolizer has little working enzyme; an ultrarapid one has extra copies. For codeine, an ultrarapid metabolizer can turn too much of it into morphine. A doctor or pharmacist decides what it means for a medicine.
Licensed CC BY-NC 4.0: free to read, share and adapt for non-commercial use, naming MyGeneLog™ and linking the exact page. Commercial use, including training or serving a commercial AI system, needs a licence — https://www.mygenelog.com/license
A gene page gathers published research; it is not a test result and not medical advice. If a gene matters to your health, talk to a doctor or a genetic counsellor.