Health Encyclopedia > Medications

codeine, diphenhydramine, and phenylephrine

Pronunciation: KOE deen, DYE fen HYE dra meen, and FEN il EFF rin

Brand: Endal CD

What is the most important information I should know about codeine, diphenhydramine, and phenylephrine?

Multum donot

Do not take this medication if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take cough or cold medicine before the MAO inhibitor has cleared from your body.

Multum donot

Do not use any cough, cold, allergy, or sleepy medication without first asking your doctor or pharmacist. Codeine, diphenhydramine and phenylephrine are contained in many combination medicines, some available over the counter. If you take certain products together you may accidentally take too much of a certain drug. Read the label of any other medicine you are using to see if it contains codeine, diphenhydramine, or phenylephrine.

Multum habit

Codeine may be habit-forming and should be used only by the person it was prescribed for. This medication should never be shared with another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it.

Multum nochild

Do not give this medication to a child younger than 2 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.

What is codeine, diphenhydramine, and phenylephrine?

Codeine is in a group of drugs called narcotics. It is a cough suppressant that affects the signals in the brain that trigger cough reflex.

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

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

The combination of codeine, diphenhydramine, and phenylephrine is used to treat cough, runny or stuffy nose, and sneezing caused by allergies, the flu, or the common cold.

Multum smoking

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

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

What should I discuss with my healthcare provider before taking codeine, diphenhydramine, and phenylephrine?

Multum donot

Do not take this medication if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take cough or cold medicine before the MAO inhibitor has cleared from your body.

If you have any of these other conditions, you may need a dose adjustment or special tests to safely take codeine, diphenhydramine, and phenylephrine:

  • asthma, emphysema, or other breathing problems;
  • heart disease or high blood pressure;
  • a history of head injury or brain tumor;
  • glaucoma;
  • diabetes;
  • liver or kidney disease;
  • an enlarged prostate or urination problems;
  • a seizure disorder;
  • severe constipation, intestinal blockage, or stomach ulcer;
  • a pancreas disorder;
  • adrenal gland disorder such as Addison's disease;
  • a thyroid disorder; or
  • a history of depression, mental illness, or drug/alcohol addiction.
Multum nopreg

FDA pregnancy category C. It is not known whether this medication is harmful to an unborn baby. However, it could cause breathing problems or addiction/withdrawal symptoms in a newborn if the mother takes the medicine during late pregnancy. Before you take acetaminophen and codeine, tell your doctor if you are pregnant or plan to become pregnant during treatment.

Multum nobrfeed

This medication may pass into breast milk and may harm a nursing baby. The use of codeine by some nursing mothers may lead to life-threatening side effects in the baby. Do not use this medication if you are breast-feeding a baby.

Multum habit

Codeine may be habit-forming and should be used only by the person it was prescribed for. Codeine should never be shared with another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it. Codeine is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.

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

Artificially-sweetened liquid forms of cold medicine may contain phenylalanine. Talk to your doctor before using this medication if you have phenylketonuria (PKU).

How should I take codeine, diphenhydramine, and phenylephrine?

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label. Cough or cold medicine is usually taken for only a short time until your symptoms clear up.

Multum nochild

Do not give this medication to a child younger than 2 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.

Measure this medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Multum food

You may take this medication with or without food. Taking it with food or milk may decrease stomach upset.

This medication may cause dry mouth. You may need to suck on ice chips or hard candy to relieve this side effect.

Multum water

Drink extra fluids to help loosen the congestion and lubricate your throat while you are taking this medication.

Talk with your doctor if your symptoms do not improve after 7 days of taking this medication. Call your doctor any time if your symptoms get worse or if you also have a fever, headache, or skin rash.

This medication can cause you to have unusual results with allergy skin tests. Tell any doctor who treats you that you are taking an antihistamine.

If you need to have any type of surgery, tell the surgeon ahead of time if you have taken a cold medicine within the past few days.

Multum rt

Store this medication at room temperature away from moisture, heat, and freezing.

Multum habit

Keep track of how much of this medicine been used from each new bottle. Codeine is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.

What happens if I miss a dose?

Since cough or cold medicine is usually taken only as needed, 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.

What happens if I overdose?

Multum emt

Seek emergency medical attention if you think you have used too much of this medicine. An overdose of codeine can be fatal.

Overdose can cause confusion, hallucinations, agitation, or seizure (convulsions).

What should I avoid while taking codeine, diphenhydramine, and phenylephrine?

Multum dizzy

This medication can cause side effects that may cause drowsiness, dizziness, or blurred vision. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Multum noalcohol

Avoid drinking alcohol. It can increase some of the side effects of this medication.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Multum donot

Do not use any cough, cold, allergy, or sleepy medication without first asking your doctor or pharmacist. Codeine, diphenhydramine and phenylephrine are contained in many combination medicines, some available over the counter. If you take certain products together you may accidentally take too much of a certain drug. Read the label of any other medicine you are using to see if it contains codeine, diphenhydramine, or phenylephrine.

What are the possible side effects of codeine, diphenhydramine, and phenylephrine?

Multum emt

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.

Multum donot

Stop taking this medication and call your doctor at once if you have any of these serious side effects:

  • confusion, hallucinations, tremors;
  • ringing in your ears;
  • extreme weakness or dizziness;
  • fast, slow, or uneven heart rate;
  • seizure (convulsions);
  • weak or shallow breathing;
  • easy bruising or bleeding; or
  • urinating less than usual or not at all.

Less serious side effects include:

  • dizziness, drowsiness, headache;
  • nausea, upset stomach, constipation;
  • blurred vision; or
  • dry mouth, nose, or throat.

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 codeine, diphenhydramine, and phenylephrine?

Multum dizzy

Before using this medication, tell your doctor if you regularly use other medicines that make you sleepy (such as cold or allergy medicine, sedatives, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by codeine, diphenhydramine, and phenylephrine.

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

  • blood pressure medications;
  • methyldopa (Aldomet);
  • reserpine;
  • an antidepressant such as amitriptyline (Elavil, Etrafon), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), imipramine (Janimine, Tofranil), nortriptyline (Pamelor), and others; or
  • a beta-blocker such as atenolol (Tenormin), carvedilol (Coreg), metoprolol (Lopressor, Toprol), propranolol (Inderal, InnoPran), sotalol (Betapace), and others.

This list is not complete and there may be other drugs that can interact with codeine, diphenhydramine, and 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.

Where can I get more information?

Your pharmacist can provide more information about codeine, 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 1996-2013 Cerner Multum, Inc. Version: 1.04. Revision date: 12/15/2010.

Your use of the content provided in this service indicates that you have read, understood and agree to the End-User License Agreement, which can be accessed by clicking on this link.

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

USNWR 2013-2014Magnet Hospital RecognitionConsumer Choice2014 Best DoctorsJoint Commission Report

Disclaimer: The information on this website is for general informational purposes only and SHOULD NOT be relied upon as a substitute for sound professional medical advice, evaluation or care from your physician or other qualified health care provider.