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]
  2. There’s no non-kosher or Chametz material found on paper or plastic plates, cups, cutlery and doesn’t need a hechsher. However, parchment papers which are coated with non-stick agent it needs a hechsher. [2]

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. [3]

References

  1. Rav Schachter on OU Pre-Pesach Webcast 5771 between minutes 91:30 and 92:30
  2. Rav Yisrael Belsky on OU Pre-Pesach Webcast 5771 between minutes 107:30 and 110:30
  3. Halichot Shlomo (vol 1, 4:24)