Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Phenylephrine is an alpha-1 adrenergic agonist that narrows blood vessels. Given by drip, it raises blood pressure during anaesthesia; as eye drops it widens the pupil; as a nasal spray it relieves congestion. It is also in many oral cold remedies (such as Sudafed PE), although a US FDA advisory committee concluded in 2023 that it does not work as a decongestant when taken by mouth.
Phenylephrine is broken down mainly by monoamine oxidase in the gut wall, which is why so little of an oral dose reaches the blood. The gene studies on it looked at ADRB2, mostly in studies of blood vessel responses in volunteers. The findings come from a few studies, and there is no CPIC or DPWG guideline.
Every published finding on gene variants and Phenylephrine. 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.
ADRB2 rs1042713: Level 3. Dosage. 2.
Studies of how quickly the body processes this medication.
Studies of how much of the drug people needed or tolerated.
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
Sympathomimetics (class) (Sympathomimetics)
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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