Vicodin

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

About Vicodin

What it is

Hydrocodone is an opioid pain medicine for moderate to severe pain, in the US most often combined with paracetamol (acetaminophen) in one tablet, and in some countries also used for cough. Sold combinations include Vicodin, Norco and Lortab.

How genes come into it

Hydrocodone acts on opioid receptors itself, but the liver enzyme CYP2D6 also turns part of it into hydromorphone, a stronger opioid. People with little CYP2D6 activity form less hydromorphone, and people with extra copies form more. CPIC has published a guideline on CYP2D6 and hydrocodone; because hydrocodone works on its own as well, the effect of the gene is smaller than for codeine or tramadol. A few studies have looked at the opioid receptor gene OPRM1, with weaker evidence.

Published guidelines

Clinical guidelines that name a gene for Vicodin. They sort people into groups by the gene copies they carry.

CPIC guideline: CYP2D6. CYP2D6 activity score 0 to 6 or more. Strong. 2021.

What research found

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

Rated evidence (7 rated variants)

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

CYP2D6 CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*5, CYP2D6*17, CYP2D6*41: Level 1A · replicated. Metabolism/PK. 6.

CYP2D6 CYP2D6*5, CYP2D6*17: Level 1A · replicated. Efficacy: Pain. 2.

OPRM1 rs62436463: Level 3. Toxicity: adverse events. 1.

SEPTIN3;WBP2NL rs739296: Level 3. Toxicity: adverse events. 1.

Metabolism (4 findings)

Studies of how quickly the body processes this medication.

CYP2D6 CYP2D6 poor metabolizers: CYP2D6 poor metabolizer is associated with decreased metabolism of hydrocodone in healthy individuals as compared to CYP2D6 normal metabolizer and ultrarapid metabolizer.

CYP2D6 CYP2D6 poor metabolizer: CYP2D6 poor metabolizer is associated with decreased metabolism of hydrocodone as compared to CYP2D6 ultrarapid metabolizer.

CYP2D6 CYP2D6*2, CYP2D6*41: CYP2D6 *2/*41 is associated with increased concentrations of hydrocodone.

CYP2D6 CYP2D6 normal metabolizer phenotype: CYP2D6 normal metabolizer is associated with increased metabolism of hydrocodone as compared to CYP2D6 poor metabolizer.

Response (5 findings)

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

CYP2D6 CYP2D6 poor metabolizer: CYP2D6 poor metabolizer is associated with decreased clinical benefit to codeine, hydrocodone, oxycodone or tramadol in people with Pain as compared to CYP2D6 normal metabolizer.

CYP2D6 CYP2D6 poor metabolizers and intermediate metabolizers: CYP2D6 intermediate metabolizer and poor metabolizer are associated with decreased response to codeine, fentanyl, hydrocodone, hydromorphone, methadone, morphine, oxycodone or tramadol in people with Neoplasms and Pain as compared to CYP2D6 normal metabolizer.

CYP2D6 rs35742686: Allele DELT is associated with increased clinical benefit to hydrocodone or oxycodone in people with Pain as compared to allele T.

MACROD2 rs76026520: Allele G is associated with increased clinical benefit to hydrocodone or oxycodone in people with Pain as compared to allele A.

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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