Fentanyl

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Fentanyl

What it is

Fentanyl is a very potent synthetic opioid, around 50 to 100 times stronger than morphine. It is used in anaesthesia, for severe pain after surgery, and as patches or fast-acting forms for long-lasting cancer pain. It is sold as Duragesic and Sublimaze, among other names.

How genes come into it

Fentanyl is broken down mainly by the liver enzyme CYP3A4, with help from CYP3A5, and studies have linked CYP3A4 variants such as rs2242480 to how much fentanyl people needed after surgery. Other studies have looked at the opioid receptor gene OPRM1, the transporter ABCB1 and COMT for dose needs and side effects, with mixed results. There is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Fentanyl. Upload your DNA file to see which of these rows apply to you.

Rated evidence (48 rated variants)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

CYP3A4 rs2242480: Level 2A · replicated. Dosage: Pain, Postoperative. 6.

OPRM1 rs1799971: Level 3. Dosage: Pain, Pain, Postoperative. 9.

OPRM1 rs1799971: Level 3. Efficacy: Pain. 6.

CYP3A5 CYP3A5*1, CYP3A5*3, CYP3A5*6: Level 3. Metabolism/PK: Pain, Pain, Postoperative. 5.

Metabolism (33 findings)

Studies of how quickly the body processes this medication.

poor metabolizers: CYP3A poor metabolizer is associated with decreased metabolism of fentanyl in people with Pain.

ABCB1 rs1128503: Genotype AG is associated with decreased exposure to fentanyl in healthy individuals as compared to genotypes AA + GG.

ABCC1 rs58572178: Allele (A)14 is associated with increased clearance of fentanyl in children with Pain and Premature Birth as compared to allele (A)13.

ABCC3 rs11079921: Allele C is associated with increased clearance of fentanyl in children with Pain and Premature Birth as compared to allele T.

Response (39 findings)

Studies of how well it worked in people carrying a variant.

rs13093031: Genotype GG is associated with increased response to fentanyl in people with Pain, Postoperative as compared to genotypes AA + AG.

rs6961071: Genotype GG is associated with increased response to fentanyl in people with Pain, Postoperative as compared to genotypes AA + AG.

ABCB1 rs1128503: Genotype AA is associated with decreased response to fentanyl in people with Neoplasms and Pain as compared to genotypes AG + GG.

ATF2 rs7583431: Allele A is associated with increased response to fentanyl in people with Pain, Postoperative as compared to allele C.

Dosing (64 findings)

Studies of how much of the drug people needed or tolerated.

rs11959113: Genotype AA is associated with increased dose of fentanyl in people with Pain, Postoperative as compared to genotypes AG + GG.

rs2952768: Genotype CC is associated with increased dose of fentanyl in people with Pain, Postoperative as compared to genotypes CT + TT.

ABCB1 rs1045642: Allele A is associated with decreased dose of buprenorphine, dihydrocodeine, fentanyl, hydromorphone, methadone, morphine, oxycodone, piritramide, tilidine or tramadol in people with Pain as compared to allele G.

ABCB1 rs1045642: Genotype GG is associated with increased dose of fentanyl in people with Pain, Postoperative as compared to genotypes AA + AG.

Other findings (9 findings)

Studies that do not fall into the groups above.

ABCB1 rs1045642: Allele A is not associated with response to fentanyl in healthy individuals as compared to allele G.

ABCB1 rs1128503: Allele G is not associated with response to fentanyl in healthy individuals as compared to allele A.

ABCB1 rs2032582: Allele A is not associated with response to fentanyl in healthy individuals as compared to allele C.

ABCB1 rs2032582: Allele T is not associated with response to fentanyl in healthy individuals as compared to allele C.

Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.

Related Drugs

More drugs from the same category

Alfenta (Opioids)

Codeine (Opioids)

Demerol (Opioids)

Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.

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Content updated September 2026.

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