Acne mechanica is an acneiform eruption that has been observed after repetitive physical trauma to the skin such as rubbing, occurring from clothing (belts and straps) or sports equipment (football helmets and shoulder pads). : 499   In addition to those mechanisms, the skin not getting enough exposure to air also contributes to the formation of acne mechanica. It is often mistaken as a rash that forms on sweaty skin that is constantly being rubbed, but in reality, it is a breakout of acne mechanica. The term "acne" itself describes the occurrence in which hair follicles (also known as pores) in the skin get clogged by oil, dead skin cells, dirt and bacteria, or cosmetic products and create a pimple. Pimples can vary in type, size, and shape, but the sole basis of them occurring is the same - the oil gland in the pore becomes clogged and sometimes infected, which creates pus in order to fight the infection and subsequently causes the development of swollen, red lesions on the skin. Signs and symptoms
The signs and symptoms at an early stage are harder to be seen. At first look, acne mechanica seems very similar to any other type of acne. However, it differs in how it is caused. A lot of acne has to do with hormones, the amount of oil production in the skin, and genetic predispositions. Acne mechanica specifically refers to the skin irritation that is formed by excess pressure, heat, and rubbing against the skin.
There are some people who are more prone to develop acne mechanica. The biggest group of people affected by this type of acne are teenagers and young adults in their twenties who already experience issues with acne on their back, shoulders, and buttocks. Other people who have a type of acne commonly described as "sandpaper acne," which is characterized as small but rough acne lesions that are not very visible but feel like sandpaper to the touch, also are more prone to developing acne mechanica. Mechanism
Acne mechanica specifically is triggered by both mechanical and heat stress on the skin working together to cause this irritation. The skin that is exposed to these stressors initially develops a harder surface to protect itself, but if the skin is continually dealing with this pressure, it gets irritated and forms a rash. At this point, it gets qualified as acne mechanica. When you are in a hot climate or are working out and your body temperature rises, the heat causes the pores in your skin to open up. The dilation of the pores makes it easier for bacteria, oil, and dead skin cells to collect in the pores and clog them. Every pore in your body has a tiny hair follicle, and the blockage causes the hair follicle to become irritated and inflamed, which ends up forming pimples; specifically acne mechanica. White blood cells flood the area of inflammation, and once they die, they accumulate on the surface of the pore, causing what is known as a "whitehead".