Phenylephrine PO

Reviewed on 2/3/2022

What Is Phenylephrine PO and How Does It Work?

Phenylephrine PO is a prescription as well as over-the-counter topical medication used for the treatment of nasal congestion.

What Are Dosages of Phenylephrine PO?

Adult and pediatric dosage


  • 5mg
  • 10mg 

Sinus Congestion

Adult dosage

  • 10 mg orally every 4 hours or as needed; not to exceed 60 mg/24 hr 

Pediatric dosage

  • Children below 12 years

Safety and efficacy not established

  • Children above 12 years
  • 10 mg orally every 4 hours or as needed; not to exceed 60 mg/24 hr 

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages.”

What Are Side Effects Associated with Using Phenylephrine PO?

Common side effects of Phenylephrine PO include:

  • Leakage of intravenous medication
  • Hypertension (Increased blood pressure)
  • Slow heart rate
  • Anxiety
  • Headache
  • Burning
  • Rebound congestion
  • Sneezing
  • Excess fluid in the lungs (pulmonary edema)
  • Metabolic acidosis
  • Decreased blood flow to the kidneys
  • Reduced urine output
  • Nausea
  • Stomach pain or upset

Serious side effects of Phenylephrine PO include:

  • none

Rare side effects of Phenylephrine PO include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


Could I Be Allergic? Discover Your Allergy Triggers See Slideshow

What Other Drugs Interact with Phenylephrine PO?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Phenylephrine PO?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Phenylephrine PO?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Phenylephrine PO?”


  • Some products may contain sulfites, which may cause allergic reactions in susceptible individuals
  • Closely monitor in hyperthyroidism, DM, heart disease, bowel obstruction/narrowing, increased intraocular pressure, BPH
  • Use caution in the elderly, in patients with bowel obstruction/narrowing, asthma, diabetes mellitus, cardiovascular disease, hyperthyroidism, hypertension, hyperplasia, increased intraocular pressure, and prostatic hyperplasia; if symptoms do not improve within 7 days or are accompanied by fever, contact healthcare professional
  • Discontinue and inform the healthcare provider if dizziness, nervousness, or sleeplessness occur
  • Hypertension may occur when used concurrently with monoamine oxidase inhibitors; use extreme caution
  • The elderly may be more predisposed to adverse effects from sympathomimetics; they often have diabetes mellitus and cardiovascular disease as well as multiple drug therapies
  • Counsel the elderly about the proper use of OTC products and the types of diseases when the drug should be avoided

Pregnancy and Lactation

  • Use with caution if the benefits outweigh risk during pregnancy
  • Lactation
    • Not known if excreted in breast milk


Allergies can best be described as: See Answer
Medscape. Phenylephrine PO.

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