The need-to-know information for Guaifenesin


Pearls and Fun Nuggets

1. It’s more than just an expectorant ☝ It has muscle relaxant and anticonvulsant properties and may also act as an NMDA receptor antagonist.[14]

2. It commonly causes dry mouth or chapped lips 😮 Drinking a glass of water is recommended with each dose of guaifenesin.[12]

3. It originates from the Guaiac tree 🌳 Similar medicines derived from the guaiac tree were in use as a generic remedy by American indigenous peoples when explorers reached North America in the 16th century. The Spanish encountered guaiacum wood “when they conquered Santo Domingo; it was soon brought back to Europe, where it acquired an immense reputation in the sixteenth century as a cure for syphilis and certain other diseases…”[15]

4. Guaifenesin may help with conception 👫 It was studied as a method to improve the possibility of conception, by thinning and increasing the stretchability (improved spinnbarkeit) of the cervical mucus, during the few days before ovulation, thus facilitating sperm penetration.[23][24]

Patient Perspectives

“Have been taking 1200 mg slow release Mucinex (plain guaifenesin) for two weeks and it has helped loosen mucus in my lungs. It does require drinking LOTS of water to be effective. In my case 64 ounces a day. Noticeable difference in breathing and timbre of my voice. All that said, hoping I can stop taking the medicine and simply work on staying hydrated.”


“It works good, you will feel the congestion breaking down. It does make you cough more to loosen up mucus and yes you probably will stay up a bit a night. I took the pill not liquid. Have to say I was surprised.”


 “Took this medication for a chest cough before I went to bed. Woke up in the night with severe nausea and felt dizzy. Tried it again a week later and same happened. I know other people who swear by it.”

Brandon Simpson, PA-C
Follow me
Latest posts by Brandon Simpson, PA-C (see all)