In each extended-release bi-layer tablet Other Information: Store at 20-25 degrees C (68-77 degrees F). 1200 mg guaifenesin extended-release bi-layer tablets. Relieves chest congestion. Thins and loosens mucus. Immediate and extended release. Unique Bi-Layer Tablet: Immediate-release layer. Extended-release layer. www.rb.com. Questions? 1-866-Mucnex (1-866-682-4639). You may also report side effects to this phone number. Please visit our website www.mucinex.com. Choose from Mucinex line of products to treat your symptoms: Mucinex - Relieves chest congestion; Thins and loosens mucus for 12 hours. Mucinex DM: Controls cough; Thins and loosens mucus for 12 hours. Mucinex D: Clears nasal/sinus congestion; Thins and loosens mucus for 12 hours. Made in England.