Is one who is burnt allowed to put aloe Vera on the burnt area on Shabbat or Yom Tov? Medicine is generally prohibited on Shabbos (pikuach nefesh is ALWAYS an exception), but even outside pikuach nefesh there are some exceptions. Smearing always prohibited, but dabbing on something without moving it on the body generally isn’t considered smearing.
Yes - from Peninei Halacha Shabbat 28:08 -
Even when using medicine is permissible, one may not apply topical medication (such as creams or ointments) to a bandage or a wound. If one applies ointment and smoothes its surface to spread it, he violates Torah law, as Memare’aĥ is a tolada of Memaĥek (Shabbat 75b; above, 18:6). It is also forbidden to place the ointment onto the body or the bandage without spreading it, out of concern that one will end up spreading it. Even if the bandage was prepared with ointment before Shabbat, one may not place it on the wound on Shabbat, out of concern that he will end up spreading it (SA 328:25).
However, to alleviate or prevent pain, the Sages allow one to place ointment directly on a wound or bandage, though one who does so must be careful to avoid spreading it. If the ointment was in a tube, he should place the tube directly on the wound. If it is in a container, one may apply the ointment using a tongue depressor or a spoon. The primary concern is that it should not be spread. When the bandage is placed on the wound, the cream will spread out along the sides. Nevertheless, as long as one does not smooth the surface intentionally, this is not prohibited (SSK 33:14; above, section 5).
Similarly, if one is in pain, he may place medicated cream on his skin and rub it in until it is completely absorbed. This is because as long as one wants all the cream to be absorbed, it is not considered Memare’aĥ. However, if one wants part of the cream to remain on the surface of the skin to make it smooth, applying the cream is prohibited by Torah law (Da’at Torah 328:26; R. Shlomo Zalman Auerbach cited in SSK ch. 33 n. 64; based on MA 316:24 and MB ad loc. 49; see above, 14:5, and Harĥavot).
Question: Is it permissible to apply aloe vero on a burn on Shabbos?
Answer: The halacha is that a person that has a minor ailment may not put medication on it. The reason is because he may come to chop up other herbs etc., which is meleches tochain. I am assuming that the burn is not so bad that the person is bedridden as a result. If he would be bedridden as a result, then he would be considered a choleh kol gufo, and he would be allowed to apply the aloe vera gel in a permitted way, but this doesn’t seem applicable to your case.