Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Sildenafil is a PDE5 inhibitor: it blocks the enzyme that breaks down cyclic GMP, so the relaxing signal from nitric oxide in blood vessels lasts longer. It is used for erectile dysfunction (Viagra) and, in a different dose, for pulmonary arterial hypertension (Revatio). Together with nitrate heart medicines it can make blood pressure fall dangerously.
Sildenafil is broken down mainly by CYP3A4, with help from CYP2C9. Studies have looked at CYP3A4, at NOS3, the gene for the enzyme that makes nitric oxide, and at GNB3, ACE and VEGFA for how well it worked. The findings come from a few studies, and there is no CPIC or DPWG guideline.
Every published finding on gene variants and Viagra. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
ACE rs4343: Level 3. Efficacy: Erectile Dysfunction. 1.
GNB3 rs5443: Level 3. Efficacy: Erectile Dysfunction. 1.
CYP3A4 CYP3A4*1, CYP3A4*22: Level 3. Metabolism/PK: Heart Failure. 1.
VEGFA rs699947: Level 3. Efficacy: Erectile Dysfunction. 1.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
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.
More drugs from the same category
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.
Content updated September 2026.
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