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

Nasal Four 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.

Nasal Four may also be used for purposes not listed in this medication guide.

Do not use Nasal Four if you have used an MAO inhibitor in the past 14 days, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine.

Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended. Cold medicine should be used only for a short time until your symptoms clear up.

Do not give Nasal Four to a child younger than 4 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

Nasal Four is usually used every 4 hours. Follow the directions on the medicine label. Never use more of this medicine than directed on the label or prescribed by your doctor. Using this medicine too long can damage the lining of your nasal passages and lead to chronic nasal congestion.

To use the nasal spray:

• Blow your nose gently. Keep your head upright and insert the tip of the bottle into one nostril. Press your other nostril closed with your finger. Breathe in quickly and gently spray the medicine into your nose. Then use the spray in your other nostril.

• Do not blow your nose for at least a few minutes after using the nasal spray.

• If the spray gets in your eyes or mouth or on your skin, rinse with water.

• If the nasal spray has not been used for longer than 24 hours, prime it by spraying 1 or 2 times into a tissue.

After each use, clean the tip of the spray bottle with a clean tissue or rinse it with hot water, making sure that no water gets into the medicine bottle. Keep the cap on the bottle when not in use.

To use the nasal drops, lie on your back with your head tilted back. Insert the correct number of drops and remain lying in this position for several minutes. Gently turn your head from side to side.

To prevent the spread of infection, do not share Nasal Four with anyone else.

Call your doctor if your symptoms do not improve after 3 days of treatment, or if you have a fever with a headache, cough, or skin rash.

If you need surgery, tell the surgeon ahead of time that you are using Nasal Four. You may need to stop using the medicine for a short time.

Store at room temperature away from moisture and heat.

You should not use Nasal Four if you are allergic to it.

Do not use Nasal Four if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Ask a doctor or pharmacist if it is safe for you to use this medicine if you have other medical conditions, especially:

• heart disease, heart rhythm disorder;

• high blood pressure;

• diabetes;

• glaucoma;

• a thyroid disorder; or

• an enlarged prostate or urination problems.

It is not known whether Nasal Four will harm an unborn baby. Do not use this medicine without a doctor's advice if you are pregnant.

It is not known whether phenylephrine nasal passes into breast milk or if it could harm a nursing baby. Do not use this medicine without a doctor's advice if you are breast-feeding a baby.

Since Nasal Four is used when needed, you may not be on a dosing schedule. If you are on a schedule, use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe dizziness or drowsiness, slow heart rate, and fainting.

Avoid getting Nasal Four in your eyes.

Ask a doctor or pharmacist before using any other cold, cough, or allergy medicine. Many combination medicines contain pseudoephedrine. Taking certain products together can cause you to get too much of this medicine.

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

Nasal Four may cause serious side effects. Stop using Nasal Four and call your doctor at once if you have:

• severe sneezing, runny or stuffy nose, redness or swelling in your nose, or other worsening nasal symptoms (may be a sign of overuse of Nasal Four);

• severe stinging, burning, or irritation inside your nose;

• severe dizziness, restless feeling, nervousness, or insomnia;

• mood changes, unusual thoughts or behavior;

• tremors or shaking; or

• little or no urination.

Side effects may be more likely in older adults.

Common side effects of Nasal Four may include:

• temporary sneezing;

• mild burning, dryness, cold feeling, or irritation inside your nose;

• headache, dizziness, weakness;

• feeling excited or restless (especially in children); 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.

Ask a doctor or pharmacist before using this medicine if you are also using any other drugs, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or dangerous effects when used together. Not all possible interactions are listed in this medication guide.

Ask a doctor or pharmacist if it is safe for you to use Nasal Four if you are also using any of the following drugs:

• other decongestants;

• an antidepressant;

• blood pressure medication; or

• diabetes medication.

This list is not complete. Other drugs may interact with phenylephrine nasal, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.