Other Information: Store between 68-77 degrees F (20-25 degrees C). Misc: 600 mg guaifenesin extended-release bi-layer tablets. Relieves chest congestion. Thins and loosens mucus. Immediate and extended release. Questions? 1-866-Mucinex (1-866-682-4639). You may also report side effects to this phone number. Unique bi-layer tablet. Immediate-release layer. Extended-release layer. Choose from the Mucinex line of products to treat your symptoms. Please visit our web site www.mucinex.com. Health. Hygiene. Home. Made in England.