Thank you for sharing your question. In simple terms, no the filler will not go bad the day after expiration, it is just advised that it is used before that deadline.
Dear Chrisannbe,you should be safe as long as the filler is used prior to expiration date. Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery