dextromethorphan, diphenhydramine, and phenylephrine

What is the most important information I should know about this medicine?

Do not use this medicine 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 use this medicine to make a child sleepy. Ask a doctor before giving the medicine to a child younger than 4 years old.

Ask a doctor or pharmacist before using any other medicine that may contain diphenhydramine. Taking too much of this medicine can lead to a fatal overdose.

What is dextromethorphan, diphenhydramine, and phenylephrine?

Dextromethorphan is a cough suppressant. Diphenhydramine is an antihistamine. Phenylephrine is a decongestant.

Dextromethorphan, diphenhydramine, and phenylephrine is a combination medicine used to treat cough, stuffy nose, and sneezing caused by allergies, the common cold, or the flu.

Dextromethorphan, diphenhydramine, and phenylephrine may also be used for purposes not listed in this medication guide.

What should I discuss with my healthcare provider before taking this medicine?

Do not use this medicine 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 this medicine is safe to use if you have ever had:

• a cough with mucus;
• an enlarged prostate or urination problems;
• high blood pressure, heart disease;
• diabetes;
• a thyroid disorder;
• glaucoma; or
• a stomach ulcer.

This medicine may contain phenylalanine. Check the medication label if you have phenylketonuria (PKU).

Ask a doctor before using this medicine if you are pregnant or breastfeeding.

How should I take this medicine?

Use exactly as directed on the label, or as prescribed by your doctor. Cold or cough medicine is only for short-term use until your symptoms clear up.

Ask a doctor before giving the medicine to a child younger than 4 years old.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

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

What happens if I miss a dose?

Since this medicine is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Overdose symptoms may include vomiting, confusion, severe drowsiness, ringing in your ears, no urination, very dry eyes and mouth, dilated pupils, fast heartbeats, tremor, agitation, hallucinations, or seizure.

What should I avoid while taking this medicine?

What are the possible side effects of this medicine?

• severe drowsiness;
• painful or difficult urination;
• fast, pounding, or uneven heartbeats;
• trouble breathing;
• confusion, anxiety, irritability, tremors;
• a seizure; or
• problems with balance or speech.

Common side effects may include:

• dizziness, drowsiness, headache;
• blurred vision, dry eyes;
• dry mouth, nose, or throat;
• upset stomach, nausea, vomiting;
• diarrhea, constipation; or
• tiredness, trouble sleeping.

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.

What other drugs will affect dextromethorphan, diphenhydramine, and phenylephrine?

Ask a doctor or pharmacist before using dextromethorphan, diphenhydramine, and phenylephrine with any other medicines, especially drugs that can cause drowsiness (such as opioid medication, sleep medicine, a muscle relaxer, or medicine for anxiety or seizures). Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Where can I get more information?

Your pharmacist can provide more information about dextromethorphan, diphenhydramine, and phenylephrine.

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.

Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2023 Cerner Multum, Inc. Version: 2.01. Revision date: 9/29/2020.