Other Information: Store at 68-77 degrees F (20-25 degrees C). Tamper Evident: Do not use if carton is open or if printed seal on blister is broken or missing. Misc: 600 mg guaifenesin & 30 mg dextromethorphan HBr extended-release bi-layer tablets. Extended-release. Immediate-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. Parents: Learn about teen medicine abuse. www.StopMedicineAbuse.org. Please visit our web site www.mucinex.com. Made in England.