Dextromethorphan is a generic over-the-counter (OTC) drug used to relieve cough. The drug comes as an oral suspension and an oral liquid capsule. How often you take it depends on the form you take.
Dextromethorphan is used in adults and certain children to relieve dry cough from minor throat or airway irritation, such as from a cold.
Dextromethorphan belongs to a group of drugs called cough suppressants.
This article describes the dosages of dextromethorphan, as well as its strengths and how to take it. To learn more about dextromethorphan, see this in-depth article.
This section describes the usual dosages of dextromethorphan. See below for details.
What are dextromethorphan’s forms?
Dextromethorphan is available as:
- an oral capsule filled with liquid (also called a softgel)
- extended-release oral liquid suspension (a type of liquid mixture)
Note: “Extended release” means the drug is released into your body slowly over a long period of time.
What strengths does dextromethorphan come in?
Dextromethorphan comes in two strengths:
- oral liquid capsule: 15 milligrams (mg)
- oral suspension: 30 milligrams per 5 milliliters (30mg/5mL)
What are the usual dosages of dextromethorphan?
The information below describes commonly recommended dosages of dextromethorphan, which is an OTC medication. Be sure to follow the package directions when taking dextromethorphan. You can also ask your doctor or pharmacist about the dosage that’s right for you.
Dosage for cough
The typical dextromethorphan dose for adults with dry cough depends on the form you’re taking.
- Dosage for oral liquid capsules: two capsules taken every 6 to 8 hours as needed (with a maximum dosage of eight capsules in a 24-hour period)
- Dosage for oral suspension: 10 mL taken every 12 hours as needed (with a maximum dosage of 20 mL in 24 hours)
If you have questions about your dextromethorphan dosage, talk with your pharmacist.
What’s the dextromethorphan dosage for children?
Dextromethorphan is used to help relieve cough in certain children caused by minor throat or airway irritation, such as from a cold. The dosage used in children is based on the form they take and their age.
Oral liquid capsules: The oral capsules are approved for use in children ages 12 years and older. The dosage is the same as the adult dosage, that is, two capsules taken every 6 to 8 hours as needed, with a maximum dosage of eight capsules in 24 hours.
Oral suspension: The oral suspension is approved for use in children ages 4 years and older. The dosage is based on the child’s age. See the table below for details.
| Age | Dosage | Frequency |
|---|---|---|
| children ages 12 years and older | 10 mL | every 12 hours; max dose of 20 mL in 24 hours |
| children ages 6 years to younger than 12 years | 5 mL | every 12 hours; max dose of 10 mL in 24 hours |
| children ages 4 years to younger than 6 years | 2.5 mL | every 12 hours; max dose of 5 mL in 24 hours |
| children younger than ages 4 years | not recommended | not applicable |
For more information about dextromethorphan’s dosage for children, talk with your child’s doctor or a pharmacist.
How to take dextromethorphan
How you take dextromethorphan depends on the form you take. Follow the package directions for the form of dextromethorphan you’ve purchased. You can also talk with your pharmacist if you have questions about how to take the drug.
For the oral liquid capsules, swallow them whole. You should not crush, cut, or chew the capsules. If you have difficulty swallowing pills, you can see this article for tips on how to take this form. You can also consider buying the oral liquid suspension form.
For the oral suspension form, you can measure out the correct dose using a teaspoon. (One teaspoon equals 5 mL). Or if giving the drug to a young child, you can use an oral syringe to measure the correct dose.
With either form, you can take the drug with or without food.
Is dextromethorphan used long term?
No. Dextromethorphan is used as a short-term treatment to relieve minor cough from throat or airway irritation.
If you have questions about how long you can take dextromethorphan to relieve cough, talk with your pharmacist or doctor.
Do not take more dextromethorphan than what’s recommended on the product label. Taking too much dextromethorphan (a toxic dose) can lead to harmful effects.
Symptoms of overdose
Symptoms caused by an overdose can include:
- nausea and vomiting
- dizziness
- drowsiness
- fast heart rate
- dry mouth
- headache
- dangerous drop in body temperature
- hallucinations
- euphoria (feeling high)
- nystagmus (repeating eyeball movements that you can’t stop)
- serotonin syndrome (too much serotonin in your body), which may cause:
- agitation
- confusion
- low blood pressure
- fever
- seizure
- loss of consciousness
In severe cases, dextromethorphan overdose can lead to coma or even death if not treated.
What to do in case you take too much dextromethorphan
Call your doctor right away if you think you’ve taken too much dextromethorphan. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.
Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.