Cold and allergy symptoms can really be bothersome. Sometimes, you just need a little relief. There are several over-the-counter drugs that can help, including Mucinex D.

Mucinex D contains two active ingredients: guaifenesin and pseudoephedrine. Guaifenesin helps loosen mucus in your chest. Pseudoephedrine temporarily helps with congestion in your nose. Together, these two ingredients work well to relieve symptoms of the common cold and allergies. These include cough, stuffy nose, sneezing, and sinus congestion and pressure.

However, there are side effects associated with the ingredients in this medication that you should know about.

Mucinex D works by combining the actions of the drugs guaifenesin and pseudoephedrine. Each ingredient can affect different parts of your body in different ways. Here are the effects you should be aware of while you take this drug.

Cardiovascular system effects

The pseudoephedrine in Mucinex D can affect your heart and increase your blood pressure. Symptoms of heart-related side effects include:

  • increased heart rate
  • pounding heart beat

If these symptoms are mild, they probably won’t bother you. However, if you feel that these side effects are severe or if they don’t go away, contact your doctor.

Nervous system effects

The active ingredients in Mucinex D can both affect your nervous system. However, these side effects are rare.

Most of the side effects of guaifenesin are mild and well-tolerated. They include:

  • dizziness
  • headache
  • drowsiness

Nervous system side effects from pseudoephedrine can include:

  • anxiety
  • restlessness
  • tremors
  • headache
  • lightheadedness
  • dizziness
  • sleeping trouble

Digestive system effects

Guaifenesin rarely causes stomach problems when you use it at recommended doses. Pseudoephedrine can cause the following side effects:

  • nausea
  • vomiting
  • loss of appetite

If you experience nausea, try taking Mucinex D with food or a glass of milk.

Skin effects and allergic reaction

A possible side effect of Mucinex D is an allergic reaction. This may cause a skin rash. If you experience a rash after taking Mucinex D, stop taking it and contact your doctor.

If you notice any of the following, call 911 or local emergency services immediately:

  • the rash is worsening
  • you have swelling of your tongue or lips
  • you have any difficulties breathing

Taking this drug if you have certain conditions increases your risk of severe side effects. Talk to your doctor before taking Mucinex-D if you have medical conditions such as:

  • high blood pressure
  • heart disease
  • diabetes
  • increased eye pressure
  • thyroid problems
  • prostate problems

It’s very important to use Mucinex D exactly as directed. Most of the severe side effects of Mucinex D can happen when you use too much. If you have any questions about how much you should use, ask your pharmacist.

The following side effects can occur if you use too much Mucinex D:

  • changes in heart rhythm
  • chest pain
  • hallucinations
  • heart attack
  • seizures
  • severe diarrhea
  • severe increase in blood pressure
  • severe nausea
  • severe stomach pain
  • severe vomiting
  • stroke
  • kidney stones
  • brain or nerve damage

Symptoms of kidney stones include:

  • fever
  • chills
  • vomiting
  • severe, persisting pain in your back or side
  • foul-smelling urine
  • cloudy urine
  • blood in your urine
  • pain or burning when you urinate
  • difficulty urinating

Symptoms of brain or nerve damage include:

  • memory or vision loss
  • arm and leg weakness
  • coordination problems

Stop using Mucinex D and contact your doctor immediately if you have any of these severe side effects.

Maximum Strength Mucinex D contains double the amount of medicine. There are no additional side effects of the stronger formula as long as you take it as directed. However, taking the stronger formula at the dosage that’s recommended for the regular formula can lead to overuse and severe side effects.

Mucinex D can help most people relieve chest and nasal congestion without side effects that are harmful or worrisome. However, this is not true for everyone, especially if you have certain medical conditions or take other drugs.

If you’re unsure if Mucinex is right for you, ask your doctor. And if you can’t take Mucinex D, check out the best natural cough remedies and the best natural antihistamines.


When should I start feeling better?

Anonymous patient


When taking Mucinex D, your symptoms should improve within 7 days. Stop taking it and call your doctor if your symptoms don’t go away or if they come back. Also, stop taking the drug if you develop a fever or rash. These could be signs of a more serious problem.

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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