Mucinex features guaifenesin as an active ingredient. This expectorant helps with nasal mucus, but “#mucinexdpregnancy” is based on the belief it can thin cervical mucus as well as it does phlegm from the respiratory system. This would make it easier for sperm to reach the egg. But the research does not support it.

Mucinex is a brand name for guaifenesin, an expectorant that thins mucus. People typically use expectorants like Mucinex when they have chest congestion to help thin mucus in the air passages to make it easier to cough up, per the U.S. National Library of Medicine.