Hello. I am  currently battling a sinus infection and very bad chest congestion and coughing. My primary care physician told me it is safe to take mucinex while nursing but when I looked up the drug information it stated there are no known studies on the safety of ingesting guafenesin while nursing.
HI, thanks for using Chat Doctor Though there are no known studies with the use of guaifenesin in breastfeeding, it is thought that the amount that would be secreted into the milk would not harm an infant especially if older than 2 months. If your baby is older than 2 months (this is the age that doctors may suggest cough meds if ill), then you can consider the use of this medication. I hope this helps