If gums whiten or sting, remove gel, rinse

https://zanderckjg432.timeforchangecounselling.com/in-office-vs-at-home-teeth-whitening-your-guide-to-expert-teeth-whitening-gilbert-and-affordable-teeth-whitening-gilbert-az-1

If gums whiten or sting, remove gel, rinse, and apply vitamin E oil; lower gel volume next time and make sure trays aren't impinging on soft tissues.