Dextromethorphan

What is dextromethorphan?

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

Dextromethorphan is used to treat a cough. It is available over-the-counter alone and is also present in many over-the-counter and prescription combination medications.

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

Important information

Do not give dextromethorphan 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.

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

Do not use any other over-the-counter cough, cold, or allergy medication without first asking your doctor or pharmacist. If you take certain products together you may accidentally take too much of one or more types of medicine. Read the label of any other medicine you are using to see if it contains dextromethorphan. Dextromethorphan will not treat a cough that is caused by smoking, asthma, or emphysema.

Before taking this medicine

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

Ask a doctor or pharmacist about using dextromethorphan if you have emphysema or chronic bronchitis.

It is unknown whether dextromethorphan is harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Dextromethorphan may pass into breast milk. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Artificially-sweetened liquid forms of cough medicine may contain phenylalanine. This would be important to know if you have phenylketonuria (PKU). Check the ingredients and warnings on the medication label if you are concerned about phenylalanine.

How should I take dextromethorphan?

Use dextromethorphan exactly as directed on the label, or as it has been prescribed by your doctor. Do not use the medication in larger amounts, or use it for longer than recommended. Cough medicine is usually taken only for a short time until your symptoms clear up.

Do not give dextromethorphan to a child younger than 4 years old.

Always ask a doctor before giving cough or cold medicine to a child. Death can occur from the misuse of cough or cold medicine in very young children.

Measure the liquid form of dextromethorphan 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.

Allow the dextromethorphan lozenge or disintegrating strip to dissolve in your mouth.

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 treatment, or if you have a fever with a headache, cough, or skin rash.

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

Store dextromethorphan at room temperature, away from heat, light, and moisture.

What happens if I miss a dose?

Since cough 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?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include nausea, vomiting, drowsiness, dizziness, difficulty breathing, fast heartbeat, or seizures (convulsions). Overdose can also result in coma or death.

What should I avoid?

Avoid drinking alcohol. It can increase some of the side effects of dextromethorphan. This medication can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Avoid taking diet pills, caffeine pills, or other stimulants (such as ADHD medications) without your doctor's advice. Taking a stimulant together with cough medicine can increase your risk of unpleasant side effects.

Do not use any other over-the-counter cough, cold, or allergy medication without first asking your doctor or pharmacist. Dextromethorphan is contained in many combination medicines available over the counter. If you take certain products together you may accidentally take too much of this medicine. Read the label of any other medicine you are using to see if it contains dextromethorphan.

Dextromethorphan side effects

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. Stop using dextromethorphan and call your doctor at once if you have any of these serious side effects:

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

• seizures or convulsions;

• confusion, hallucinations; or

• slow, shallow breathing.

Less serious side effects are more likely, such as stomach upset.

This is not a complete list of dextromethorphan 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?

Before taking dextromethorphan, tell your doctor if you are using any of the following drugs:

• celecoxib (Celebrex);

• cinacalcet (Sensipar);

• darifenacin (Enablex);

• imatinib (Gleevec);

• quinidine (Quinaglute, Quinidex);

• ranolazine (Ranexa)

• ritonavir (Norvir);

• sibutramine (Meridia);

• terbinafine (Lamisil);

• medicines to treat high blood pressure; or

• antidepressant medications such as amitriptyline (Elavil, Etrafon), bupropion (Wellbutrin, Zyban), fluoxetine (Prozac, Sarafem), fluvoxamine (Luvox), imipramine (Janimine, Tofranil), paroxetine (Paxil), sertraline (Zoloft), and others.

This list is not complete and there are numerous other drugs that can interact with dextromethorphan. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Further information

What does my medication look like?

Dextromethorphan is available over the counter under many different brand and generic names. Ask your pharmacist any questions you have about this medication, especially if it is new to you.

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.