Phenylephrine
Pronunciation: (fen-il-EF-rin).
- Generic name
- Phenylephrine
- Brand names
- Sudafed PE (oral, OTC), Neo-Synephrine (nasal/oral, OTC), Vazculep (IV injection, prescription), Many other OTC cold/allergy combination products
- Drug class
- Alpha-1 adrenergic agonist (decongestant at oral/nasal OTC doses; vasopressor at prescription IV doses)
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What Phenylephrine is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Phenylephrine works
Phenylephrine is a selective alpha-1 adrenergic receptor agonist. At oral/nasal OTC doses it produces local vasoconstriction in nasal mucosa, reducing swelling and congestion. At prescription IV doses it produces systemic arterial vasoconstriction, raising blood pressure in vasodilatory hypotension; the IV form has an effective half-life of approximately 5 minutes and no confirmed boxed warning in its current FDA label. (3)
What Phenylephrine is used for
Nasal congestion (colds, allergies, sinusitis) — OTC oral/nasal decongestant
Relieves nasal and sinus congestion by narrowing swollen blood vessels in the nasal passages. Does not treat the underlying cause of congestion or speed recovery from a cold. (2) (3)
Clinically important hypotension in anesthesia and septic shock — prescription IV use
Used in adults to increase blood pressure when hypotension results primarily from vasodilation, in the settings of anesthesia and vasodilatory (e.g. septic) shock. Administered only by healthcare professionals as an IV bolus or continuous infusion, diluted and titrated to effect. (2) (3)
Before taking Phenylephrine
Do not take / not appropriate for
- hypersensitivity to the product or components only. (Contraindication) (2)
- Confirmed NO boxed warning present in this label (checked specifically, since this campaign has been finding missing boxed warnings elsewhere — none exists here to elevate). (Contraindication) (2)
Tell your clinician about
(2) (3)How to take Phenylephrine
- OTC oral/nasal products: follow the package label; typically taken every 4 hours as needed, without exceeding the labeled maximum doses in 24 hours. Do not double a dose. Prescription IV phenylephrine is administered only by a healthcare professional in a hospital or monitored setting — it must be diluted before use and is not a self-administered medicine.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2) (3)
Missed dose
For OTC use, phenylephrine is taken as needed for symptoms rather than on a fixed schedule, so there is generally no formal missed-dose rule — take the next dose when needed for symptoms, without doubling up. The IV prescription form is administered and monitored entirely by clinical staff, so a patient-directed missed-dose rule does not apply.
Overdose
Seek immediate medical attention or contact a poison control center if an overdose of oral/nasal phenylephrine is suspected. Symptoms of overdose can include severe headache, high blood pressure, irregular heartbeat, seizures, or hallucinations. The injectable form is given only under direct medical supervision with continuous monitoring, which minimizes overdose risk in that setting. (2) (3)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms.
Nausea
Incidence: Common
Headache
Incidence: Common
Nervousness, dizziness, or trouble sleeping (oral/nasal use)
Incidence: Reported; seek medical attention promptly if these occur, and let the clinician you see advise on whether to continue or stop it
Fast, pounding, or irregular heartbeat
Incidence: Uncommon; seek medical attention
Severe headache or significant blood pressure rise
Incidence: Uncommon; seek medical attention
Serious warnings
Do not take oral/nasal phenylephrine if you are using, or have used within the past 2 weeks, a monoamine oxidase inhibitor (MAOI) such as isocarboxazid, phenelzine, selegiline, or tranylcypromine — this combination can cause a serious, potentially life-threatening interaction — serious
Symptoms: Do not take oral/nasal phenylephrine if you are using, or have used within the past 2 weeks, a monoamine oxidase inhibitor (MAOI) such as isocarboxazid, phenelzine, selegiline, or tranylcypromine — this combination can cause a serious, potentially life-threatening interaction. Seek medical advice before combining phenylephrine with any other medication.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2) (3)
Seek medical attention promptly if you experience nervousness, dizziness, or sleeplessness with oral/nasal phenylephrine — let the clinician you see advise on whether to continue or stop it — serious
Symptoms: Seek medical attention promptly if you experience nervousness, dizziness, or sleeplessness with oral/nasal phenylephrine — let the clinician you see advise on whether to continue or stop it. Seek immediate medical attention for any signs of a severe allergic reaction (rash, swelling of the face/lips/tongue/throat, difficulty breathing).
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2) (3)
People with high blood pressure, diabetes, an enlarged prostate, thyroid disease, or heart disease should tell their healthcare provider before using phenylephrine in any form, as it can affect blood pressure and heart rate — serious
Symptoms: People with high blood pressure, diabetes, an enlarged prostate, thyroid disease, or heart disease should tell their healthcare provider before using phenylephrine in any form, as it can affect blood pressure and heart rate.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2) (3)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Monoamine oxidase inhibitors (MAOIs) | Do not use oral/nasal phenylephrine with, or within 2 weeks of stopping, an MAOI — this combination can cause a serious, potentially life-threatening interaction (severe blood pressure elevation). | (2) |
| Other stimulant decongestants or blood-pressure-affecting medicines | Combining phenylephrine with other decongestants or medications that raise blood pressure or heart rate may increase the risk of side effects. Inform your healthcare provider about all medications and supplements you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Inform your doctor if you are pregnant or planning pregnancy before using phenylephrine in any form; discuss the specific clinical situation with your healthcare provider, as this page's sources do not establish detailed pregnancy safety data beyond a general disclosure recommendation for the OTC form. (2) (3)
Breastfeeding
Inform your doctor if you are breastfeeding before using phenylephrine in any form; this page's sources recommend disclosure to your healthcare provider rather than providing specific quantitative breastfeeding safety data. (2) (3)
Children
OTC oral/nasal phenylephrine products are not recommended for children under 4 years of age; use in children aged 4-11 should follow product labeling and pediatric healthcare provider guidance. The prescription IV form's safety and effectiveness in pediatric patients is a decision for the treating hospital team and is not addressed by the consumer sources reviewed for this page. (2) (3)
Renal_impairment
For prescription IV phenylephrine (vasopressor use), the FDA label reports altered responsiveness rather than a simple reduction: in patients with liver cirrhosis (Child-Pugh Class B or C), dose-response data show decreased responsiveness to phenylephrine, so larger-than-usual doses may be needed within the recommended range. In patients with end-stage renal disease on hemodialysis, dose-response data show increased responsiveness, so lower doses should be considered. Phenylephrine is extensively metabolized by the liver, with only about 12% of a dose excreted unchanged in urine. For OTC oral/nasal use, people with significant kidney or liver disease should ask their healthcare provider or pharmacist before use. (2) (3)
Hepatic_impairment
For prescription IV phenylephrine (vasopressor use), the FDA label reports altered responsiveness rather than a simple reduction: in patients with liver cirrhosis (Child-Pugh Class B or C), dose-response data show decreased responsiveness to phenylephrine, so larger-than-usual doses may be needed within the recommended range. In patients with end-stage renal disease on hemodialysis, dose-response data show increased responsiveness, so lower doses should be considered. Phenylephrine is extensively metabolized by the liver, with only about 12% of a dose excreted unchanged in urine. For OTC oral/nasal use, people with significant kidney or liver disease should ask their healthcare provider or pharmacist before use. (2) (3)
Monitoring
(2) (3)Storage
Store OTC oral/nasal products at room temperature, away from excess heat and moisture, out of reach of children, following the product label. Prescription IV phenylephrine is stored and handled by healthcare facility staff according to the product label.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
United States (prescription IV phenylephrine hydrochloride injection, e.g. Vazculep)
Indication: Clinically important hypotension resulting primarily from vasodilation, in anesthesia and septic/vasodilatory shock
Dose summary: IV bolus: 50 mcg to 250 mcg. Continuous infusion in the perioperative setting: 0.5 to 1.4 mcg/kg/minute, titrated to effect. Continuous infusion in vasodilatory shock: 0.5 to 6 mcg/kg/minute, titrated to effect. Must be diluted before administration; administered only by healthcare professionals with blood pressure monitoring.
Renal context: In patients with end-stage renal disease undergoing hemodialysis, dose-response data show increased responsiveness to phenylephrine; the FDA label advises considering lower doses in this population. (3)
General (OTC oral/nasal decongestant)
Indication: Nasal/sinus congestion
Dose summary: Follow the specific product's label; typically dosed every 4 hours as needed, not exceeding the labeled 24-hour maximum. Not for children under 4 years.
Renal context: No specific renal dose-adjustment scheme is established for OTC oral/nasal phenylephrine in the consumer sources reviewed; people with kidney disease should check with a pharmacist or healthcare provider before use. (2)
Hepatic guidance
For prescription IV phenylephrine, the FDA label reports decreased responsiveness in patients with liver cirrhosis (Child-Pugh Class B or C), so larger-than-usual doses within the recommended range may be needed, titrated to blood pressure response. Phenylephrine is extensively hepatically metabolized. No specific hepatic dose-adjustment scheme exists for OTC oral/nasal phenylephrine in the sources reviewed.
Frequently asked questions
What is Phenylephrine used for?
As an over-the-counter oral or nasal product, phenylephrine relieves nasal and sinus congestion from colds, allergies, or sinusitis. As a prescription intravenous medicine, it is used in hospital settings to raise blood pressure in adults with clinically important hypotension during anesthesia or septic shock.
What are the side effects of Phenylephrine?
Common side effects of the oral/nasal form include nausea, headache, and sometimes nervousness, dizziness, or trouble sleeping. Contact a healthcare provider if these persist or if you notice a fast or irregular heartbeat, severe headache, or signs of an allergic reaction.
How should I take Phenylephrine?
Follow the specific product's label. OTC oral/nasal phenylephrine is typically taken every 4 hours as needed, without exceeding the labeled maximum. Do not adjust your dose without medical guidance. The injectable prescription form is given only by healthcare professionals in a monitored setting.
Can I take Phenylephrine with other medications?
Do not use oral/nasal phenylephrine with, or within 2 weeks of stopping, a monoamine oxidase inhibitor (MAOI) — this combination can cause a serious interaction. Tell your healthcare provider about all medications and supplements you take before using phenylephrine.
Is phenylephrine safe with kidney or liver disease?
For the prescription IV form, liver cirrhosis is associated with reduced responsiveness (so a clinician may need larger doses within the approved range), while end-stage kidney disease on dialysis is associated with increased responsiveness (so a clinician typically uses lower doses). For OTC oral/nasal use, check with a pharmacist or healthcare provider if you have significant kidney or liver disease.
What is the mechanism of action of Phenylephrine?
Phenylephrine is a selective alpha-1 adrenergic receptor agonist. At oral/nasal OTC doses it produces local vasoconstriction in nasal mucosa, reducing swelling and congestion. At prescription IV doses it produces systemic arterial vasoconstriction, raising blood pressure in vasodilatory hypotension; the IV form has an effective half-life of approximately 5 minutes and no confirmed boxed warning in its current FDA label. (3)
What is the generic name of Phenylephrine?
The generic name is Phenylephrine. It is sold under brand names including Sudafed PE (oral, OTC), Neo-Synephrine (nasal/oral, OTC), Vazculep (IV injection, prescription), Many other OTC cold/allergy combination products.
What class of drug is Phenylephrine?
Phenylephrine is classed as: Alpha-1 adrenergic agonist (decongestant at oral/nasal OTC doses; vasopressor at prescription IV doses).
References
- Phenylephrine — MedGuideGlobal internal product recordMedGuideGlobal · Internal database · accessed 2026-08-03 · source 1
- Phenylephrine (Oral): MedlinePlus Drug InformationMedlinePlus, U.S. National Library of Medicine · United States · accessed 2026-08-07 · source 2
- Phenylephrine Hydrochloride Injection — FDA prescribing information, DailyMedUS FDA (prescribing information via DailyMed) · United States · accessed 2026-08-07 · source 3
- DAYTIME COLD AND FLU MINI SOFTGELS (ACETAMINOPHEN, DEXTROMETHORPHAN HBR, PHENYLEPHRINE HCL) CAPSULE, LIQUID FILLED [SHIELD PHARMACEUTICALS CORP] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 4
- Daytime Cold and Flu — FDA approval record (Drugs@FDA M012)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- Phenylephrine — RxNorm normalized drug concept (RXCUI 221139)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient Phenylephrine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Nasal Decongestant PE10 mg, 25 mg · hhh pharmaceuticals
- Medi-First Plus Sinus Decongestant10 mg · sportpharm llc
- NASAL and SINUS DECONGESTANT5 mg · jhk inc dba american safety & first aid
- PREPARATION H6.25 mg · haleon us holdings llc
- Biorphen.1 mg/mL, 10 mg/mL · dr. reddy's laboratories inc.
- Neo-Synephrine Maximum1 g00mL, .5 g00mL · bf ascher and co inc
- Gencare-Nasal Decongestant PE10 mg · pioneer life sciences, llc
- IMMPHENTIV100 ug/mL · hikma pharmaceuticals usa inc.
- ValuMeds Nasal Decongestant Phenylephrine HCl10 mg · cabinet health p.b.c.
- PhysiciansCare Sinus Non-Drowsy10 mg · acme united corporation
Canada
- MINIMS PHENYLEPHRINE HYDROCHLORIDE
- MYDFRIN
- HEMORRHOIDAL RELIEF
- NEO-SYNEPHRINE 10 MG/ML
- SUDAFED PE
- TRIAMINIC THIN STRIPS NASAL CONGESTION