What is phenylephrine?

Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).

Phenylephrine is used to treat nasal congestion and sinus pressure caused by allergies, the common cold, or the flu. Phenylephrine may be used to treat congestion of the tubes that drain fluid from your inner ears, called the eustachian (yoo-STAY-shun) tubes.

Phenylephrine may also be used for other purposes not listed in this medication guide.


You should not use this medication if you are allergic to phenylephrine.

Do not use phenylephrine if you have taken a monoamine oxidase inhibitor (MAOI) such as furazolidone (Furoxone), isocarboxazid (Marplan), linezolid (Zyvox), phenelzine (Nardil), procarbazine (Matulane), or tranylcypromine (Parnate) in the last 14 days. Serious, life-threatening side effects can occur if you take phenylephrine before the MAO inhibitor has cleared from your body.

If you have certain conditions, you may need a dose adjustment or special tests to safely use this medication. Before you take phenylephrine, tell your doctor if you are allergic to any decongestants, or if you have:

  • heart disease, heart rhythm disorder;
  • high blood pressure;
  • circulation problems (such as Raynaud's syndrome);
  • diabetes;
  • glaucoma;
  • a thyroid disorder;
  • kidney disease;
  • an enlarged prostate or urination problems;
  • sleep problems, anxiety; or
  • mental illness such as bipolar disorder.

FDA pregnancy category C. Is not known whether this medication will harm an unborn baby. Before you take phenylephrine, tell doctor if you are pregnant.

Phenylephrine may pass into breast milk and could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Older adults may be more likely to have side effects from this medication.

Disintegrating and liquid forms of cold medicine may contain sugar or artificial sweeteners (phenylalanine). This would be important to know if you have diabetes or phenylketonuria (PKU). Check the ingredients and warnings on the medication label if you are concerned about sugar or phenylalanine.

Do not use any other over-the-counter cold, allergy, or cough medication without first asking your doctor or pharmacist. Phenylephrine is contained in many medicines available over the counter. If you take certain products together you may accidentally take too much phenylephrine. Read the label of any other medicine you are using to see if it contains phenylephrine or another decongestant.

Avoid taking diet pills, caffeine pills, or other stimulants (such as ADHD medications) without your doctor’s advice. Taking a stimulant together with a decongestant can increase your risk of unpleasant side effects.

Avoid smoking. It can add to the effects of phenylephrine in decreasing blood flow, which can lead to uncomfortable symptoms.

Avoid drinking alcohol while you are taking phenylephrine.

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Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include feeling restless or nervous, severe dizziness, sweating, vomiting, hallucinations, fast or uneven heart rate, fainting, seizure (convulsions), and weak or shallow breathing.

Cold medicine is usually taken only as needed, so you may not be on a dosing schedule. If you are taking the medication regularly, take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at your next regularly scheduled time. Do not take extra medicine to make up the missed dose.

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Side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using phenylephrine and call your doctor at once if you have a serious side effect such as:

  • severe dizziness, restless feeling, nervousness, or insomnia;
  • unusual thoughts or behavior;
  • feeling like you might pass out;
  • fast, pounding, or uneven heartbeat;
  • tremors or shaking;
  • numbness, tingling, or cold feeling in your hands or feet; or
  • urinating less than usual or not at all.

Less serious side effects may include:

  • headache, dizziness;
  • feeling excited or restless (especially in children);
  • upset stomach; or
  • mild sleep problems.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may report side effects to FDA at 1-800-FDA-1088.

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Tell your doctor about all other medications you use, especially:

  • other decongestants, including nasal sprays;
  • digoxin (digitalis, Lanoxin);
  • medicine to treat diabetes;
  • medicines to treat high blood pressure such as reserpine, guanethidine (Ismelin), methyldopa (Aldomet), and others;
  • migraine headache medicine such as ergotamine (Ergomar), naratriptan (Amerge), sumatriptan (Imitrex) or zolmitriptan (Zomig);
  • an antidepressant such as amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Janimine, Tofranil), and others;
  • a beta-blocker such as atenolol (Tenormin), carvedilol (Coreg), metoprolol (Lopressor, Toprol), propranolol (Inderal), sotalol (Betapace), and others; or
  • a calcium channel blocker such as amlodipine (Norvasc), diltiazem (Tiazac, Cartia, Cardizem), felodipine (Plendil), nifedipine (Procardia, Adalat), verapamil (Calan, Covera, Isoptin, Verelan), and others.

This list is not complete and there may be other drugs that can interact with phenylephrine. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.

Other Names

Ah-Chew D, Despec-SF, Dimetapp Children's Cold & Allergy, Dimetapp Cold Drops, Lusonal, Nasop, Nasop12, Neo-Synephrine, Sudafed PE, Sudafed PE Extra Strength, Sudafed PE Quick Dissolve, Sudogest PE, Triaminic Thin Strips Cold, Triaminic Thin Strips Infant Decongestant, Triaminic Thin Strips Nasal Congestion, Triaminic Toddler Congestion Thin Strips, phenylephrine, PediaCare Children's Decongestant, Phenyl-T, and Sudafed PE Children's Nasal Decongestant

Available Strengths & Dosages

Route Form Strength
oral tablet hydrochloride 10 mg

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Copyright 1996-2004 Cerner Multum, Inc. Version 2.05. Revision date 8/23/04

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