Robitussin DM Dosages: Your GoodRx Guide

Coughing brought on by a cold or the flu can be painful and annoying. Robitussin DM is a popular over-the-counter (OTC) option to help ease your cough. And there are multiple Robitussin DM products with different active ingredients available.

All Robitussin DM products contain dextromethorphan (DM), a cough suppressant. Many also contain guaifenesin, an expectorant that helps thin mucus. And some include an antihistamine, such as doxylamine, to help with sleep. What’s more, Robitussin DM offers formulations for both adults and children.

Below, we’ll review Robitussin DM dosages for adults and children.

What’s the typical Robitussin DM dosage for adults?

Robitussin DM products are available as oral capsules and liquids. Liquid Robitussin DM can be a good option if you have trouble swallowing pills. If you’re taking a liquid Robitussin DM medication, use the included medicine cup to measure your doses.

Each Robitussin DM product is unique when it comes to the types and amounts of active ingredients. Be sure to read the OTC label on your selected product for details.

Robitussin Maximum Strength DM capsules

Each Robitussin Maximum Strength DM capsule (“Robitussin DM capsules”) contains:

• 10 mg of dextromethorphan

• 200 mg of guaifenesin

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The adult dosage for Robitussin DM capsules is 2 capsules by mouth every 4 hours. Don’t take more than 12 capsules in 24 hours.

Robitussin Cough and Chest Congestion DM liquid

This cough syrup is the classic Robitussin DM product that you’re likely familiar with. Every 20 mL dose of Robitussin Cough and Chest Congestion DM (“Robitussin DM”) liquid contains:

• 20 mg of dextromethorphan

• 200 mg of guaifenesin

The adult dosage of Robitussin DM liquid is 20 mL by mouth every 4 hours. Don’t take more than 6 doses (120 mL) in 24 hours.

Robitussin DM liquid also comes in a sugar-free version. The active ingredients and dosage information are the same as those for the standard version.

Robitussin Maximum Strength Cough and Chest Congestion DM liquid

Every 20 mL of Robitussin Maximum Strength Cough and Chest Congestion DM (“maximum strength Robitussin DM”) liquid contains:

• 20 mg of dextromethorphan

• 400 mg of guaifenesin

The adult dosage of maximum strength Robitussin DM liquid is 20 mL by mouth every 4 hours. Don’t take more than 6 doses (120 mL) in 24 hours.

Maximum strength Robitussin DM liquid comes in three flavors: raspberry, honey, and elderberry. They all have the same active ingredients and dosage information. There are no added medicinal benefits that come with the flavors; they’re only intended to appeal to different tastes.

Nighttime Robitussin Maximum Strength DM liquid

This version of Robitussin DM contains an ingredient that can help you sleep. Every 20 mL of Nighttime Robitussin Maximum Strength DM (“nighttime Robitussin DM”) liquid contains:

• 30 mg of dextromethorphan

• 12.5 mg of doxylamine succinate (an antihistamine for sleep)

The adult dosage of nighttime Robitussin DM liquid is 20 mL by mouth every 6 hours. Don’t take more than 4 doses (80 mL) in 24 hours. Nighttime Robitussin DM liquid comes in two flavors: wildberry and honey.

What’s the typical Robitussin DM dosage for children?

Children’s dosages for Robitussin DM are typically based on age. Adolescents age 12 years and older can follow the adult dosages described above. Children under 12 years old should only take Robitussin DM products that include dosage information for their age range.

Children’s Robitussin Cough and Chest Congestion DM liquid

This is one of the Robitussin DM products available for kids under 12 years old. It comes in grape and elderberry flavors. Every 5 mL of Children’s Robitussin Cough and Chest Congestion DM (“children’s Robitussin DM”) liquid contains:

• 5 mg of dextromethorphan

• 100 mg of guaifenesin

The dosages of children’s Robitussin DM liquid are as follows:

• Age 12 years and older: Give 20 mL by mouth every 4 hours. Don’t give more than 6 doses (120 mL) in 24 hours.

• Age 6-11 years old: Give 10 mL by mouth every 4 hours. Don’t give more than 6 doses (60 mL) in 24 hours.

• Age 4-5 years old: Give 5 mL by mouth every 4 hours. Don’t give more than 6 doses (30 mL) in 24 hours.

• Under 4 years old: The medication is not recommended.

Children’s Robitussin Honey Cough and Chest Congestion DM liquid

Children’s Robitussin Honey Cough and Chest Congestion DM liquid has slightly different amounts of the active ingredients listed above. Every 5 mL of the honey-flavored liquid contains:

• 5 mg of dextromethorphan

• 50 mg of guaifenesin

The dosages of children’s Robitussin Honey Cough and Chest Congestion DM are as follows:

• Age 12 years and older: Give 20 mL by mouth every 4 hours. Don’t give more than 6 doses (120 mL) in 24 hours.

• Age 6-11 years old: Give 10 mL by mouth every 4 hours. Don’t give more than 6 doses (60 mL) in 24 hours.

• Age 4-5 years old: Give 5 mL by mouth every 4 hours. Don’t give more than 6 doses (30 mL) in 24 hours.

• Under 4 years old: The medication is not recommended.

Children’s Robitussin Nighttime Long-Acting DM liquid

The “nighttime” version of children’s Robitussin DM liquid contains an ingredient to help with sleep. Every 5 mL of children’s Robitussin Nighttime Long-Acting DM liquid contains:

• 7.5 mg of dextromethorphan

• 1 mg of chlorpheniramine (an antihistamine for sleep)

The dosages of children’s Robitussin Nighttime Long-Acting DM liquid are as follows:

• Age 12 years and older: Give 20 mL by mouth every 6 hours. Don’t give more than 4 doses (80 mL) in 24 hours.

• Age 6-11 years old: Give 10 mL by mouth every 6 hours. Don’t give more than 4 doses (40 mL) in 24 hours.

• Under 6 years old: The medication is not recommended.

Are there any dosage adjustments for health conditions?

Robitussin DM doesn’t typically need dosage adjustments for health conditions. But there are cases in which you may need to avoid Robitussin DM.

Talk to a healthcare provider before taking Robitussin DM if you:

• Are pregnant or breastfeeding

• Have diabetes (for liquids that contain sugar only)

• Have a cough with a lot of mucus

• Have a long-lasting cough from smoking or a chronic lung condition, such as asthma

• Have a cough that lasts more than 7 days

• Have a cough that’s accompanied by a fever, rash, or long-lasting headache

• Have taken a monoamine oxidase inhibitor (MAOI) within the last 14 days (2 weeks)

What happens if you miss a dose of Robitussin DM?

Missing a dose of Robitussin DM is OK because it’s typically taken only as needed. If you forget to take a dose and you’re coughing, you can go ahead and take your next dose. Just make sure you’ve waited the recommended time between doses (4 or 6 hours) that’s listed on the package.

You should only take Robitussin DM if you have a cough. Follow the dosage instructions for your specific product, and don’t take more than the maximum daily dosage.

What should you do if you take too much Robitussin DM?

Taking an extra dose of Robitussin DM by mistake is unlikely to cause serious harm. But you may be more likely to experience side effects, such as nausea, dizziness, or drowsiness. Typically, these side effects are mild and go away over time. Avoid driving or doing other things that require focus if you take an extra dose of Robitussin DM.

On the other hand, taking an excessive amount of Robitussin DM can be harmful, due to the dextromethorphan component. Large amounts of dextromethorphan can lead to serious side effects, such as seizures and irregular heart rhythms. In severe cases, taking large amounts can even be fatal.

If you think you’ve taken too much Robitussin DM, you can talk to your healthcare provider or call Poison Control at 1-800-222-1222. If you experience serious side effects, get emergency treatment right away.

How to save on Robitussin DM

There are ways to save on Robitussin DM products, which are available as both brand-name and generic medications. By having your provider write you a prescription for Robitussin DM, GoodRx may be able to help you save over 50% off the average retail price.

The generic version of Robitussin DM liquid at certain pharmacies may cost as low as $4.42 with a free GoodRx coupon. The generic version of Robitussin DM capsules at certain pharmacies may cost as low as $20.12 with a free GoodRx coupon.

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Written by:

Elizabeth Cambria, PharmD

Elizabeth Cambria is a licensed, registered pharmacist, and certified pharmacist immunizer in the state of Pennsylvania. She graduated with a Doctor of Pharmacy from the University of Pittsburgh School of Pharmacy.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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