Mucinex clears sinuses by clearing and loosening mucus, notes WebMD. This clears congestion of the airways and makes breathing easier. Mucinex does not shorten the length of the common cold, and only provides temporary relief from cough, bronchitis and other breathing issues.
Mucinex is taken orally, usually every 12 hours with a full glass of water. The dosage depends on age, medical condition and response to treatment, notes WebMD. Mucinex is not recommended for children under 12 years old, unless permitted by a doctor. Before taking Mucinex, check with a doctor to rule out allergies to any of the active or inactive ingredients. Possible side effects include nausea and vomiting.