Key takeaways
Guaifenesin ER (Mucinex ER, Mucus Relief ER) and codeine/guaifenesin (Cheritussin AC) are both used to treat cough, but they have some key differences. Guaifenesin ER is an over-the-counter expectorant that helps loosen mucus in your chest, making it easier to cough up. It is taken every 12 hours and is generally well-tolerated with few side effects. On the other hand, codeine/guaifenesin is a prescription-only medication that combines an expectorant with an opioid to both loosen mucus and reduce the urge to cough. It is taken every 4 hours as needed and is meant for short-term use due to the risk of addiction and side effects like drowsiness and nausea. While guaifenesin ER is available as a generic medication, codeine/guaifenesin is also available in generic form but is a controlled substance due to the presence of codeine. Both medications can be used by those 12 and older.
