How long does the Colgate Optic White Overnight Teeth Whitening Pen last? June 17, 2021 13:02 Updated The whitening pen can last up to 35 days when used as directed (depending on individual usage) Related articles How long will the whitening effect last? Is there an interval in between treatment cycles? How much time should I wait to go through the whitening cycle again? Is the pen safe for enamel? How should I clean the pen brush? What if I am unhappy with the results? Comments 0 comments Article is closed for comments.