Guaifenesin is an expectorant drug used to treat mucous congestion in the respiratory tract such as the throat and lungs.

Pronunciation: gwhy-FEN-e-sin

What are guaifenesin’s uses?

Guaifenesin is a mucous decongestant used in cough syrup to treat a phlegmy cough (usually due to an upper respiratory tract infection) by loosening mucous from the throat and lungs.

The drug is extracted from the guaiac tree, a plant used by Native Americans for its medicinal properties.

Guaifenesin works by drawing water into the bronchi (the passageways that allow air into the lungs), which thins the mucous trapped there and loosens it, allowing it to be coughed up more easily.

What dosage should you take?

The typical dose for adults is 200 to 400mg every four hours.

The typical dose for children two to six years old is 50 to 100mg every four hours, children six to 12 years old, 100 to 200mg every four hours.

Children younger than two-years-old should not take guaifenesin.

Always check the correct dosages with your Clicks pharmacist first.

What special precautions should you take?

  • Tell your Clicks pharmacist or doctor if you are allergic to guaifenesin, or if you have any other allergies.
  • Be sure to share your medical history with your Clicks pharmacist or doctor before using guaifenesin.
  • If you are pregnant or breastfeeding, use guaifenesin only if your doctor has determined that the benefits outweigh the risks.
  • Take care when driving or performing tasks that require you to be alert, as it could impair your functioning.

Guaifenesin should be avoided if you suffer from porphyria (a group of rare genetic disorders that affect mainly the skin or nervous system).

Guaifenesin should be used with caution if you suffer from the following conditions:

  • Asthma
  • A history of bronchospasm (tightening of the muscles around the bronchial tubes)
  • Peptic ulcer

What drug interactions could you experience?

No systemic drug interactions have been noted for guaifenesin, but always inform your doctor or Clicks pharmacist what prescription and non-prescription medications, vitamins, nutritional supplements and herbal products you are taking or plan to take.

What are guaifenesin’s side effects?

Side effects may include:

  • Nausea
  • Headache
  • Dizziness
  • Stomach ache
  • Thrombocytopenia (a disorder characterised by a low blood platelet count)
  • Runny nose
  • Bronchospasm (tightening of the muscles around the bronchial tubes)
  • Rash
  • Blurred vision
  • Slow heart rate 

Discontinue use if hives (urticaria) or other allergic symptoms develop.

This is not a complete list of side effects. It’s essential that you call your doctor should you notice any severe or odd side effects.

What are the overdose symptoms?

Call a doctor or an ambulance immediately if you notice the following symptoms, which may be due to either an overdose or an allergic reaction:

  • Vomiting
  • Convulsions
  • Swollen lips, eyes or tongue
  • Fainting
The accuracy of this information was checked and approved by Clicks' pharmacist Waheed Abdurahman in April 2015