Dextromethorphan is a cough suppressant. It affects the signals in the brain that trigger cough reflex.

Doxylamine is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

NyQuil Cough is used to treat cough, runny or stuffy nose, sneezing, itching, and watery eyes caused by allergies, the common cold, or the flu.

NyQuil Cough will not treat a cough that is caused by smoking, asthma, or emphysema.

NyQuil Cough may also be used for purposes not listed in this medication guide.

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

Do not give this medication 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.

You should not use antihistamine medication to make a child sleepy.

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. Cough or cold medicine is usually taken only for a short time until your symptoms clear up.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Call your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash.

If you need surgery or medical tests, tell the surgeon or doctor ahead of time if you have taken NyQuil Cough within the past few days.

Store at room temperature away from moisture and heat. Do not allow the liquid to freeze.

You should not use this medicine if you are allergic to dextromethorphan or doxylamine.

Do not use NyQuil Cough 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.

Do not give this medication 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.

You should not use antihistamine medication to make a child sleepy.

To make sure NyQuil Cough is safe for you, tell your doctor if you have:

• high blood pressure, heart disease;

• a thyroid disorder;

• a blockage in your digestive tract (stomach or intestines);

• liver or kidney disease;

• diabetes;

• cough with mucus, or cough caused by emphysema or chronic bronchitis;

• bladder obstruction or other urination problems; or

• if you take potassium (Cytra, Epiklor, K-Lyte, K-Phos, Kaon, Klor-Con, Polycitra, Urocit-K).

It is not known whether NyQuil Cough will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.

Dextromethorphan and doxylamine may pass into breast milk and may harm a nursing baby. Antihistamines may also slow breast milk production. Ask a doctor before using this medicine if you are breast-feeding.

Artificially sweetened cough or cold medicine may contain phenylalanine. If you have phenylketonuria (PKU), check the medication label to see if the product contains phenylalanine.

Since NyQuil Cough 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.

Drinking alcohol can increase certain side effects of dextromethorphan and doxylamine.

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

This medicine may cause blurred vision or impair your thinking or reactions. Avoid driving or operating machinery until you know how NyQuil Cough will affect you.

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

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

• severe dizziness or anxiety;

• a light-headed feeling, like you might pass out;

• little or no urinating; or

• liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of NyQuil Cough may include:

• drowsiness, dizziness;

• nervousness;

• sleep problems (insomnia); or

• feeling restless or excited (especially in children).

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.

Taking this medicine with other drugs that make you sleepy or slow your breathing can worsen these effects. Ask your doctor before taking NyQuil Cough with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.