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Mucinex and Mucinex DM both contain an expectorant that helps loosen mucus. Mucinex DM also contains a drug that helps reduce coughing. Both have slightly different side effects.

When you need some help shaking that chest congestion, Mucinex and Mucinex DM are two over-the-counter drugs that might help. Which one do you reach for? Here’s some information comparing these two drugs to help you figure out if one of them might work better for you.

Mucinex and Mucinex DM both contain the drug guaifenesin. This is an expectorant. It helps loosen mucus from your lungs so that your coughs are more productive. A productive cough brings up the mucus that causes chest congestion. This helps you breathe better. It also makes it easier for you to get rid of germs that may be trapped in the mucus that you cough up.

Mucinex DM contains an additional drug called dextromethorphan. This drug helps control your cough. It works by affecting signals in your brain that trigger your cough reflex. This lessens your coughing. You might find this ingredient’s action particularly helpful if long bouts of coughing have made your throat sore and made it harder for you to sleep.

Regular tablets

Both Mucinex and Mucinex DM are available as tablets you take by mouth. You can take one or two tablets of either drug every 12 hours. For either drug, you should not take more than four tablets in 24 hours. The tablets should not be used in people younger than 12 years.

Shop for Mucinex.

Maximum-strength tablets

Mucinex and Mucinex DM tablets also both come in maximum-strength versions. These medicines contain double the amount of active ingredients. You should take no more than one maximum-strength tablet every 12 hours. Do not take more than two tablets in 24 hours.

Shop for Mucinex DM.

The packaging for the regular-strength and maximum-strength products is similar. However, the packaging for the maximum-strength product includes a red banner across the top of the box that indicates that it’s maximum strength. Be sure to double check if you’re taking the regular version or the maximum-strength version to ensure you don’t accidentally take too much.


There is also a liquid version of Mucinex DM available, but only in the maximum-strength form. Talk to your doctor or pharmacist to decide which form is right for you. Mucinex DM liquid is only for people 12 years or older.

Shop for liquid Mucinex DM.

There are Mucinex liquid products that are made especially for children 4 to 11 years of age. These products are labeled “Mucinex Children’s” on the package.

Shop for children’s Mucinex.

The drugs in Mucinex and Mucinex DM don’t usually cause noticeable or bothersome side effects at the recommended dosage. Most people tolerate these medications very well. However, at higher dosages, the likelihood of side effects from the drugs in Mucinex and Mucinex DM increases. The chart below lists examples of possible side effects of Mucinex and Mucinex DM.

Common side effectsMucinexMucinex DM
nausea, vomiting, or both
stomach pain
Serious side effectsMucinexMucinex DM
feeling jittery, agitated, or restless*
kidney stones*
very severe nausea or vomiting or both

*when used at a high dosage

If you take other medications, talk to your doctor or pharmacist to make sure the drugs don’t interact with Mucinex or Mucinex DM. Some drugs for treating depression, other psychiatric disorders, and Parkinson’s disease can interact with the dextromethorphan in Mucinex DM. These drugs are called monoamine oxidase inhibitors, or MAOIs. Examples of these drugs include:

  • selegiline
  • phenelzine
  • rasagiline

The interaction between these drugs and Mucinex DM can cause a serious reaction known as serotonin syndrome. This reaction can be life threatening. Symptoms of serotonin syndrome include:

  • increased blood pressure
  • increased heart rate
  • high fever
  • agitation
  • overactive reflexes

Do not take Mucinex at the same time as an MAOI. You should also wait at least two weeks after stopping treatment with an MAOI before using Mucinex DM.

Keep reading: Serotonin syndrome symptoms, treatment, and more »

Misuse warning

Combining this drug with alcohol can be extremely dangerous.

Also, dextromethorphan, one of the ingredients in Mucinex DM, is a commonly misused drug. It can cause a high or euphoria when used in high doses. It can even cause hallucinations. This has been called “robo-tripping” or “skittling.” This type of misuse is very dangerous and can possibly lead to death.

Taking the following steps can help ensure that you get the drug that’s right for you. For the best results:

  • Make sure to specify to your pharmacist whether your cough is an unproductive (dry) cough or a productive (wet) cough.
  • Drink plenty of water while taking Mucinex or Mucinex DM to help loosen the mucus that’s causing your cough and congestion.
  • Stop using Mucinex or Mucinex DM if your cough lasts longer than 7 days, if it comes back after going away, or if you get a fever, rash, or a headache that won’t go away. These could be signs of a serious illness.