why do boxers put vaseline on their face

Boxers put Vaseline on their face primarily to reduce friction and protect their skin during a fight. Vaseline makes the skin soft, stretchy, and slippery, which helps punches slide off rather than sticking and tearing the skin. This reduces the likelihood of cuts and abrasions. It also helps limit bleeding by protecting small wounds and forming a barrier against sweat and other irritants. The application is usually focused on areas of the face most vulnerable to impact, such as the nose, lips, cheekbones, and eyebrows. However, it's applied sparingly to avoid excess running into the eyes or creating unfair advantages.