Indications
Guaifenesin (also spelled guaiphenesin) is an expectorant used to relieve chesty, productive coughs, where thick mucus (phlegm) is hard to cough up, for example with colds, flu or bronchitis. It is often combined with other ingredients such as Dextromethorphan, Diphenhydramine, Pseudoephedrine or Menthol in cough syrups.
How It Works
Guaifenesin thins and loosens the mucus in the airways and increases the amount of watery fluid in it, so it is easier to cough up and clear from the chest.
Dosage and Administration
- Adults and children 12 years and over: usually 200 to 400 mg every 4 hours when needed (for a 100 mg/5 ml syrup, 10 to 20 ml), no more than 2.4 g in 24 hours.
- Extended-release tablets: usually 600 mg to 1.2 g every 12 hours, no more than 2.4 g in 24 hours. Swallow whole; do not crush or chew.
- Combination syrups: follow the dose on the label, as it depends on all the ingredients.
- Children under 12 years: only as directed on the label or by a doctor. Do not give cough and cold medicines to children under 6 years unless a doctor advises.
Drink plenty of water while taking it, as this helps loosen mucus. Use a measuring cup or spoon for syrups.
Interactions
Guaifenesin alone has few important interactions. Combination products need more care: those with Diphenhydramine add to drowsiness with alcohol, sleeping tablets and sedatives; those with Dextromethorphan should not be taken with MAO inhibitor antidepressants or within 2 weeks of stopping them, and need care with SSRIs; those with Pseudoephedrine can interact with blood pressure medicines. Do not take two cough or cold products together without checking the ingredients.
Contraindications
- Allergy to guaifenesin or any ingredient of the product.
- Combination products: check the label, as other ingredients have their own restrictions (for example, high blood pressure, heart disease or glaucoma).
Side Effects
Usually well tolerated. Occasionally nausea, vomiting, stomach upset, dizziness, headache or rash. Combination products may also cause drowsiness or sleeplessness, depending on the ingredients.
Get urgent medical help if you have signs of a serious allergic reaction (swelling of the face or throat, difficulty breathing). See a doctor if the cough lasts more than 7 days, keeps coming back, or comes with high fever, rash, a persistent headache, chest pain, breathlessness, wheezing or blood in the phlegm.
Pregnancy and Lactation
Avoid in the first 3 months of pregnancy, and use later in pregnancy or while breastfeeding only if a doctor or pharmacist advises it. Combination products need extra caution.
Precautions and Warnings
Not meant for dry, tickly coughs, or long-term coughs from smoking, asthma or emphysema, unless a doctor advises. Check combination products for sugar or alcohol content if you have diabetes or avoid alcohol. If drowsy, do not drive or use machines.
Overdose
Too much can cause nausea, vomiting and drowsiness; very large amounts of combination syrups can be more dangerous because of the other ingredients. Seek medical help, and bring the bottle with you.
Therapeutic Class
Expectorant (cough medicine).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze syrups.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.