Learn a Drug a Day - Guaifenesin

Today's drug is guaifenesin.
What is guaifenesin indicated for?
INDICATIONS : 

• It is an expectorant used for the temporary relief of coughs caused by certain respiratory tract infections (e.g., common cold, sinusitis, bronchitis) and other breathing illnesses. 
• This product is usually not used for ongoing cough from smoking or long-term breathing problems (e.g., chronic bronchitis, emphysema). 

How does guaifenesin work?
MECHANISMS OF ACTION : 

• It works by thinning and loosening mucus in the airways, clearing congestion, making coughs more productive and making breathing easier. 

How is guaifenesin being used?
ROUTE OF ADMINISTRATION : 

• It is taken orally as tablets or liquid.
• Take this medication by mouth with or without food, usually every 4 hours. 
• Do not take more than 6 doses in a 24-hour period. 
• Drink plenty of fluids while taking this medication. Fluids will help to break up mucus and clear congestion. 
• For liquid forms, measure the dose with the dosing device provided with this medication. Do not use a household spoon. 

Is there any contraindication?
CONTRAINDICATIONS : 

• Hypersensitivity to guaifenesin.

Are there any possible side effects?
SIDE EFFECTS : 

• Side effects from this medication are unlikely. Many people using this medication do not have serious side effects. A very serious allergic reaction to this drug is rare. 
• Some possible side effects : 
• Difficulty in breathing, swelling of the face, neck, tongue or throat (these are signs of a severe allergic reaction).
• Nausea or vomiting, stomach pain. This usually only occurs when more medicine is taken than recommended on the packaging.
• Dizziness, drowsiness, headache
• Rash 
• Decreased uric acid levels 
• Urinary calculi (result of a hard mass of mineral salts in the urinary tract.)

What precautions are necessary?

PRECAUTIONS : 

It should not be used in patients with : 

• Persistent cough e.g. occurs with smoking, asthma, chronic bronchitis, or emphysema
• Cough accompanied by excessive secretions
• Cough with a fever, rash, or persistent headache
• Porphyria.

Liquid forms of this product may contain sugar and/or alcohol. Caution is advised if patients have diabetes, alcohol dependence, or liver disease. 

Guaifenesin may interfere with certain urinary diagnostic tests.

Guaifenesin or its metabolites may cause color interference with the VMA (vanillylmandelic acid) test for catechols. It may also falsely elevate the level of urinary 5-HIAA (5-hydroxyindoleacetic acid) in certain serotonin metabolite chemical tests because of color interference.

Pregnancy and breastfeeding:  

• Safe use in pregnancy has not been established relative to possible adverse effects on fetal development. Therefore, these products should not be used in pregnant patients unless, in the judgment of the physician, the potential benefits outweigh possible hazards.
• It is not known whether guaifenesin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when these products are administered to a nursing woman and a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

References : 

1. Guaifenesin by Palmetto State Pharmaceuticals.

2. Guaifenesin by RxList.

3. Guaifenesin by MIMS Malaysia.