When you're congested, mucus can settle into your chest. It's not always easy to get rid of mucus. That's why there's Mucinex. Mucinex removes excess mucus in your lungs/chest to provide fast and effective relief. -Mucinex is a convenient, easy –to-take, guaifenesin bi-layer tablet that works in 2 ways. -The white layer immediately releases the medicine. -The blue layer works steadily, releasing medicine hour after hour that lasts for up to 12 hours.