It is forbidden to apply oil or cream [on Tish’a B’Av] even to a small area of the body. One is also forbidden to use cosmetics, like powders or salves, to beautify the skin or provide a nice fragrance. This prohibition applies specifically to anointing for the sake of pleasure; applying creams for medicinal purposes, however, is permitted. Therefore, one may apply Vaseline to dry lips or put on an anti-itch cream (Sh.A. 554:15). One may, similarly, put on mosquito repellant.
One may not smell spices on Tish’a B’Av, because doing so is pleasurable and one should curtail one’s pursuit of pleasures on the day on which our Holy Temple was destroyed. Granted, there are [halachic authorities] who rule leniently [on this issue] because [smelling fragrances] is not one of the five prohibitions (M.A.); nonetheless, most poskim hold that one should act strictly on Tish’a B’Av (Sh.A. 559:7, Sha’ar HaTziyun 556:1). See the footnote regarding smoking.