Robitussin DM: Uses, Dosage, Side Effects, Warnings

What you should know before taking this strong, fast-acting medication

Robitussin DM is an over-the-counter cough suppressant and expectorant. This medicine helps to control your cough and thin secretions, so it is more productive.

A combination of guaifenesin and dextromethorphan, it is widely available under the brand name Robitussin and the generic Tussin.

This article discusses Robitussin DM cough syrup, its uses, and potential side effects. It also includes dosing information and warnings.

Robitussin cold medicine
 Scott Olson / Getty Images News / Getty Images

Common Uses

The ingredients in this medicine help to loosen mucus and suppress coughing. People commonly take this medicine for coughs associated with colds, allergies, the flu, and other respiratory illnesses.

Robitussin DM and its generic counterparts contain dextromethorphan HBr 10mg, which is a cough suppressant, and guaifenesin 100mg, which is an expectorant.

It should not be used in children under 6 without talking to the child's doctor first. 


  • Adults 12 and older: Two teaspoons every four hours as needed for cough. Do not take more than six doses in 24 hours.
  • Children ages 6 to 12: One teaspoon every four hours. Do not take more than six doses in 24 hours.

Side Effects

Every medication has the potential to cause side effects. Most are minor and the benefits outweigh the risks.

  • Drowsiness or dizziness
  • Hives or skin rash
  • Nausea, stomach pain or vomiting

Rare but serious side effects that should be reported to your healthcare provider immediately:

  • Confusion
  • Excitement, nervousness or restlessness
  • Severe nausea and vomiting
  • Slurred speech
  • Seizures or convulsions - in children
  • Shakey movements - in children
  • Slow or troubled breathing - in children


Do not use this medication if you are taking an MAOI (medication for depression, psychiatric, emotional conditions or Parkinson's disease) or for two weeks after stopping an MAOI.

Ask a healthcare provider before using this medicine if you have a chronic cough that is caused by asthma, smoking, or emphysema.

If you have a cough that produces a lot of mucus, taking a cough suppressant can be problematic. Suppressing the cough can lead to secondary infections such as pneumonia because the mucus sits in the lungs rather than being expelled by coughing.

Talk to your healthcare provider prior to taking this medicine if you are pregnant or breastfeeding as well.

Stop use and ask a healthcare provider if:

  • Pain or cough worsens or lasts more than seven days
  • Cough occurs with fever, headache, or rash that won't go away

Do not give Robitussin or other cough suppressants to children under 6.

Misuse and Overdose

A National Institute on Drug Abuse survey found that 3% of high school students admit to misusing dextromethorphan (DXM). In high doses, DXM can cause hallucinations, psychosis, agitation, and possibly even overdose.

Signs of an overdose include breathing problems, blue-tinged fingernails and lips, increased body temperature, drowsiness, an unsteady gait, and muscle twitches. If you suspect someone has taken too much DXM, call poison control at 1-800-222-1222 or seek immediate medical treatments. 

Frequently Asked Questions

  • What does Robitussin DM do?

    Robitussin DM is a cough medicine. It contains an expectorant (guaifenesin) and a cough suppressant (dextromethorphan). Robitussin DM helps to thin mucus and calm a cough. 

  • What is the difference between plain Robitussin and Robitussin DM?

    The active ingredient in plain Robitussin is guaifenesin. Robitussin DM also contains an additional medication, dextromethorphan, that helps to quiet the cough reflex. The DM stands for dextromethorphan.

  • Who should not take Robitussin DM?

    Robitussin DM should not be given to children under 6 years of age. Do not use Robitussin if you are taking an MAOI (medication for depression, psychiatric, emotional conditions, or Parkinson's disease).

    If you have a chronic cough that is caused by asthma, smoking, or emphysema, talk to your healthcare provider before taking Robitussin DM.

  • Is Robitussin DM for sleep?

    Robitussin DM is not specifically marketed for sleep. However, if you have a cough that is keeping you awake, the dextromethorphan in the cough medicine can help suppress the cough so you can sleep.

    Another formulation, Robitussin Nighttime DM, may make you sleepy. It contains the antihistamine doxylamine succinate instead of guaifenesin, which can cause drowsiness.

  • Is Robitussin DM good for dry cough?

    Yes, Robitussin DM can be used to treat a dry cough. Dextromethorphan is a cough suppressant that helps to quiet a dry cough.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Shadkam MN, Mozaffari-Khosravi H, Mozayan MR. A Comparison of the Effect of Honey, Dextromethorphan, and Diphenhydramine on Nightly Cough and Sleep Quality in Children and Their ParentsThe Journal of Alternative and Complementary Medicine. 2010;16(7):787-793. doi:10.1089/acm.2009.0311

  2. Taylor CP, Traynelis SF, Siffert J, Pope LE, Matsumoto RR. Pharmacology of dextromethorphan: Relevance to dextromethorphan/quinidine (Nuedexta®) clinical usePharmacology & Therapeutics. 2016;164:170-182. doi:10.1016/j.pharmthera.2016.04.010

  3. Dolansky G, Rieder M. What is the evidence for the safety and efficacy of over-the-counter cough and cold preparations for children younger than six years of age?Paediatr Child Health. 2008;13(2):125–127. doi:10.1093/pch/13.2.125

  4. Bem JL, Peck R. Dextromethorphan An Overview of Safety IssuesDrug Safety. 1992;7(3):190-199. doi:10.2165/00002018-199207030-00004

  5. National Institute on Drug Abuse. Over-the-counter medicines drug facts.

  6. Icahn School of Medicine at Mount Sinai. Dextromethorphan overdose.

Additional Reading
  • "Robitussin Cough Product Labeling." Wyeth Consumer Healthcare 2007. 

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.