Mucinex DM is an over-the-counter medication indicated to alleviate the symptoms of cough or chest congestion. This medication contains two active ingredients: dextromethorphan HBr, which helps suppress cough symptoms, and guaifenesin, an expectorant that helps break up chest mucus. One dose of Mucinex DM is effective for 12 hours in patients over the age of 12. Side effects are generally mild but should be discussed with a doctor if they occur.
Stomach Upset
Patients can develop an upset stomach after taking a dose of Mucinex DM. These stomach upset side effects can include nausea and vomiting, explains Drugs.com, a peer-reviewed drug information website for consumers. Certain patients may experience a decreased appetite in conjunction with these side effects. Eating a small snack or meal can help limit the occurrence of these stomach upset symptoms in certain patients.
Skin Rash
Treatment with Mucinex DM can cause skin rash side effects to emerge in certain patients. Red, irritated patches of skin can appear across the body and may begin to itch. If these side effects persist or worsen during Mucinex DM treatment, affected patients should contact a doctor.
Headache or Dizziness
While receiving treatment with Mucinex DM, patients can develop side effects of headache or dizziness, explains KidsHealth.org, a children's health information website supported by the Nemours Foundation. These side effects can be uncomfortable and may lead to decreased concentration at work or school. Sensations of dizziness may cause affected patients to become unstable upon standing or when attempting to walk. Patients who experience recurrent episodes of dizziness should remain seated until this sensation passes to prevent additional injury from tripping or falling. Severe side effects, such as extreme dizziness, restlessness, anxiety, confusion, hallucinations or nervousness during Mucinex DM treatment should be immediately reported to a doctor.
Allergic Reaction
Infrequently, patients taking Mucinex DM for the first time can experience an allergic reaction to this medication. If this occurs, affected patients may develop difficulty breathing, heart rate abnormalities, hives, dizziness, headache or facial swelling. Without immediate medical intervention, these allergic reaction symptoms can be life-threatening.
