Dextromethorphan is a medication commonly used to relieve cough. It is found in many over the counter cold and flu products in the United States.
This medication works on the brain to reduce the urge to cough. Although it is widely used for short term cough relief, dextromethorphan is also included in certain prescription medications for other medical conditions.
In addition to treating cough, dextromethorphan is combined with other drugs to treat pseudobulbar affect and major depressive disorder in adults. Its effects, recommended dose, and safety profile depend on the specific product and whether it is used alone or as part of a combination medication.
Indications for use
Dextromethorphan is approved by the US Food and Drug Administration as an antitussive, meaning it temporarily relieves cough caused by minor throat and bronchial irritation, such as irritation related to the common cold.
It is also approved in combination with quinidine for the treatment of pseudobulbar affect, a condition that causes sudden, uncontrollable episodes of laughing or crying.
In addition, a combination of dextromethorphan and bupropion is approved for the treatment of major depressive disorder in adults.
How to take it
How dextromethorphan is taken depends on the specific product and whether it is used by itself or combined with other medications.
Dosing for cough in adults and children
For over the counter cough relief in adults and children 12 years and older, a typical dose of dextromethorphan is 10 to 20 mg every 4 hours, or 30 mg every 6 to 8 hours, depending on the formulation. The maximum recommended dose is generally 120 mg within a 24 hour period.
For children 6 to 11 years old, lower doses are recommended based on age and weight, following the product label instructions. Dextromethorphan should not be used in children under 4 years old, and multi ingredient cough and cold products are generally avoided in children under 6 years old.
Different forms of dextromethorphan
Dextromethorphan is available in several forms, including syrups, liquid filled capsules, tablets, extended release suspensions, and orally disintegrating strips.
Liquid forms should be shaken well before use and measured with the dosing device provided. Capsules and extended release tablets should be swallowed whole and not crushed or chewed. Orally disintegrating products are placed on the tongue and allowed to dissolve completely.
Some products combine dextromethorphan with guaifenesin, an expectorant, or with other cold and flu ingredients. Each combination product has its own dosing instructions, which should be followed carefully.
Dosing for other approved uses
For pseudobulbar affect, the dextromethorphan and quinidine combination is taken as prescribed. Treatment usually begins with a lower dose that is increased to a maintenance dose taken twice daily.
For major depressive disorder, the dextromethorphan and bupropion combination is taken by mouth according to a specific schedule prescribed by a healthcare provider, usually twice daily.
Possible side effects
When taken at recommended doses for cough, dextromethorphan is generally well tolerated. Common side effects may include dizziness, drowsiness, nausea, vomiting, and stomach discomfort.
In combination products, side effects may also be related to the other active ingredients. With the dextromethorphan and quinidine combination, possible side effects include diarrhea, dizziness, and changes in heart rhythm, such as QT prolongation.
The dextromethorphan and bupropion combination may cause dizziness, nausea, dry mouth, decreased appetite, and sleepiness.
At high doses or when misused, dextromethorphan can lead to confusion, agitation, hallucinations, and dissociation. An overdose may require medical attention and supportive care.
Contraindications for use
Dextromethorphan should not be used by people who are currently taking monoamine oxidase inhibitors or who have taken them within the past 14 days, due to the risk of serotonin syndrome.
Caution is also needed when dextromethorphan is used with other medications that increase serotonin levels, such as certain antidepressants, because of the risk of serotonin syndrome. Symptoms may include agitation, rapid heart rate, sweating, muscle stiffness, and changes in blood pressure.
The combination of dextromethorphan and quinidine should not be used in people with certain heart rhythm disorders or in those taking other medications that can prolong the QT interval.
Anyone with a known allergy to dextromethorphan or any ingredient in the product should not use it. As with all medications, use during pregnancy or while breastfeeding should be discussed with a healthcare professional.
Abuse and misuse risk
Although dextromethorphan is considered safe when used as directed, taking high doses can cause serious neurologic and psychiatric effects. Misuse and recreational use have been reported, especially among adolescents.
Large amounts of dextromethorphan can cause agitation, hallucinations, dissociation, and problems with coordination. Safe use requires following labeled dosing instructions and avoiding alcohol or other substances that affect the brain.