How do I know when warts are gone after freezing them?

When they are gone . Basically they are gone when they stay gone. Often one can under treat and the wart will come right back, or improve slightly. These otc freezing solutions are just not as helpful as the liquid nitrogen we use in the office. And in sensitive areas warts may require several visits to get a good cosmetic result.
They either fall... ...Off a few days later, or they don't. If they don't, they were inadequately treated and need a second treatment. The home-use freezing treatment is not as cold as the liquid nitrogen used by dermatologists, so if the warts are still there after two home treatments, you'll need to see a dermatologist.