Guaifenesin is an expectorant. It helps loosen congestion in your chest and throat. Includes guaifenesin side effects, interactions and indications. Easy-to-read patient tips for guaifenesin covering how it works, benefits, risks, and best practices. Description Guaifenesin is used to help clear mucus or phlegm (pronounced flem) from the chest when you have congestion from a cold or flu. It works by thinning the mucus or phlegm in the lungs. This medicine is available both over-the-counter (OTC) and with your doctor's prescription. Guaifenesin is in countless cold medicines, but does it actually work? Here’s what the clinical evidence really says about this common expectorant. Exposes the medication guaifenesin (Humibid, Humibid LA, Robitussin, Organidin NR, Fenesin, Mucinex), a drug used for the treatment of cough associated with colds and minor upper respiratory tract infections. Guaifenesin comes as a tablet, a capsule, an extended-release (long-acting) tablet, dissolving granules, and a syrup (liquid) to take by mouth. The tablets, capsules, dissolving granules, and syrup are usually taken with or without food every 4 hours as needed. The extended-release tablet is usually taken with or without food every 12 hours. Guaifenesin is used to treat coughs and congestion caused by the common cold, bronchitis, and other breathing illnesses. Learn about side effects, drug interactions, dosages, warnings, and more. Guaifenesin is an expectorant used for wet cough. It helps loosen phlegm in the throat and chest so you can cough it up more easily. Guaifenesin is an immediate-release medication that's available as a tablet and liquid solution. It's taken by mouth, typically every 4 hours, by adults and children. Most people experience few to no side effects after taking this medication as directed. Guaifenesin, also known as glyceryl guaiacolate, which is sold under many brand names including Mucinex, [3] is an expectorant medication taken by mouth and marketed as an aid to eliminate sputum from the respiratory tract. Find patient medical information for Guaifenesin (Mucinex, Robitussin, and others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings.