Good day to you and thank-you very much for your question. A lot of people are actually quite sensitive to heat. When the skin is very hot, it swells very slightly (not noticeably that you can see a “swollen face”), but the is very slight swelling in the skin. This very slight swelling caused by heat, will cause the actual entrance to all the hair follicles to become slightly narrower. When this happens. It makes it more difficult for the sebum from the oil glands to escape from the follicle and “leak” onto the skin, so it becomes trapped inside the follicle, causing a blockage. This is when the pimples are formed. So if you use thick creams or make-up over the skin, and this swelling from the heat happens, you can imagine the blockages are exacerbated and you’ll get quite a few pimples from this. Chances are that you are already predisposed to this kind of problem or that you struggle with the odd blockages any way, so when it gets hot, the problem is just made worse.