Which foods, medications, cosmetics, and toiletries are Chametz?

From Halachipedia

Chametz before Pesach

  1. Strictly speaking a toothpaste doesn’t need to be kosher lepesach, however, if it’s available one should have a kosher lepesach toothpaste. [1]

Chametz sent in mail before Pesach

  1. If one sent Chametz in the mail to a friend before Pesach and it’ll still be in the mail at the beginning of Purim, the sender should do Bitul Chametz for that Chametz as well. [2]

References

  1. Rav Schachter on OU Pre-Pesach Webcast 5771 between minutes 91:30 and 92:30
  2. Halichot Shlomo (vol 1, 4:24)