Dextromethorphan dosing: Forms, strengths, and more

Dextromethorphan comes as an oral tablet and an oral liquid suspension. How often it’s taken depends on its form.

Dextromethorphan is approved for use in adults and certain children to treat dry coughs caused by minor throat or airway irritation, such as from a cold.

Dextromethorphan is a generic medication and belongs to a drug class called cough suppressants, also known as antitussives. Dextromethorphan is available in a brand-name version called Robitussin.

This article describes the dosage of dextromethorphan, as well as its strength and how to take it.

The following information describes dosages that are commonly used or recommended for dextromethorphan. Be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs. In some cases, doctors may adjust your dosage from those mentioned here.

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Dextromethorphan is approved to treat dry cough. The typical dextromethorphan dosage for adults with dry cough depends on its form.

For the oral suspension, the dosage for adults is 10 mL every 12 hours, with a maximum of 20 mL to be taken in a 24-hour period. For the oral capsules, the dosage for adults is 2 softgel capsules every 6 to 8 hours as needed.

Always follow your prescribing doctor’s instructions. Notify them if you experience any side effects that may prevent you from taking your medication.

Dextromethorphan suspension is used to help treat dry cough in children ages 4 years and older. Dextromethorphan oral capsules are used in children ages 12 years and older.

The oral capsule dosage is the same as for adults: 2 softgel capsules every 6 to 8 hours, as needed.

How you take dextromethorphan depends on its form. Always follow the package directions for the form of dextromethorphan you’ve purchased. You can also talk with a pharmacist if you have questions about how to take the drug.

Swallow the oral softgel capsules. Avoid chewing, crushing, or cutting the capsules. For the oral suspension, shake the bottle well before use and measure the correct dose using the provided measuring cup.

Both forms can be taken at any time of day, with or without food.

Dextromethorphan is typically taken for a limited time to relieve symptoms of a dry cough. If the cough lasts longer than 7 days, or goes away and then comes back, stop taking dextromethorphan and speak with a doctor.

Do not take more dextromethorphan than the package directs, as this may lead to harmful effects.

In severe cases, dextromethorphan overdose may be life threatening or lead to coma if not treated.

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.

Here are answers to some commonly asked questions about dextromethorphan’s dosage.

Dextromethorphan starts to work after your first dose. Because of how the medication works, you likely won’t feel it working in your body. But you can keep an eye on your symptoms to see whether dextromethorphan is working to ease your cough.

If you have other questions about what to expect from your dextromethorphan treatment, talk with a pharmacist.

If you don’t feel that dextromethorphan is effectively treating your cough, do not take more than the maximum dosage. Instead, reach out to a doctor for further evaluation, especially if your cough is accompanied by a fever, rash, or persistent headache.

Doctors may then try prescription medications to manage your condition.

You should not take dextromethorphan if you are currently taking a prescription monoamine oxidase inhibitor (MAOI) or if you have taken one in the past 2 weeks. These medications are used to treat depression, some psychiatric conditions, or Parkinson’s disease.

You should also avoid taking dextromethorphan if you’re allergic to any of its ingredients.

Disclaimer: Medical News Today 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.