Dextromethorphan and doxylamine

Generic name: dextromethorphan and doxylamine [ DEX-troe-me-THOR-fan-an-dox-IL-a-meen ]
Brand names: NyQuil Cough, Robitussin Maximum Strength Nighttime Cough, Robitussin Nighttime Cough DM, Safetussin PM, Robitussin Maximum Strength Nighttime Cough DM, Good Sense Night Time Cough
Dosage form: oral liquid (30 mg-12.5 mg/20 mL; 30 mg-12.5 mg/30 mL; 7.5 mg-3.125 mg/5 mL)
Drug class: Upper respiratory combinations

Medically reviewed by Drugs.com on Aug 17, 2023. Written by Cerner Multum.

What is dextromethorphan and doxylamine?

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.

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

Dextromethorphan and doxylamine will not treat a cough that is caused by smoking, asthma, or emphysema.

Dextromethorphan and doxylamine may also be used for purposes not listed in this medication guide.

Dextromethorphan and doxylamine side effects

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

Dextromethorphan and doxylamine may cause serious side effects. Stop using dextromethorphan and doxylamine 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 dextromethorphan and doxylamine 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.

Related/similar drugs

benzonatate, diphenhydramine, Benadryl, guaifenesin, dextromethorphan, Mucinex, Bromfed DM

Warnings

Do not use dextromethorphan and doxylamine 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.

Before taking this medicine

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

Do not use dextromethorphan and doxylamine 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 dextromethorphan and doxylamine 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 dextromethorphan and doxylamine 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.

How should I take dextromethorphan and doxylamine?

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 dextromethorphan and doxylamine within the past few days.

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

Dextromethorphan and doxylamine dosing information

Usual Adult Dose for Cough and Nasal Congestion:

Dextromethorphan-doxylamine 15 mg-6.25 mg/15 mL oral liquid:
30 mL orally every 6 hours not to exceed 4 doses daily.

Dextromethorphan-doxylamine 7.5 mg-3.125 mg/5 mL oral liquid:
20 mL orally every 6 hours not to exceed 4 doses daily.

Usual Pediatric Dose for Cough and Nasal Congestion:

Dextromethorphan-doxylamine 15 mg-6.25 mg/15 mL oral liquid:
12 years or older: 30 mL orally every 6 hours not to exceed 4 doses daily.

Dextromethorphan-doxylamine 7.5 mg-3.125 mg/5 mL oral liquid:
12 years or older: 20 mL orally every 6 hours not to exceed 4 doses daily.

What happens if I miss a dose?

Since dextromethorphan and doxylamine 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.

What happens if I overdose?

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

What should I avoid while taking dextromethorphan and doxylamine?

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 dextromethorphan and doxylamine.

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

What other drugs will affect dextromethorphan and doxylamine?

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 dextromethorphan and doxylamine with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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