You guys — it's hot as hell out there. But you probably didn't need us to tell you that. The beads of sweat pooling on your forehead likely gave it away. And also maybe the sweat sliding down your back. Things tend to get extra-steamy in the summer — whether you're purposefully sweating during a workout or slowly melting into a puddle on a stuffy subway platform. (Quick aside: Is there a more truly uncomfortable situation?) But as those slick rivers run down your back, you may be asking yourself — is all this extra moisture good for your skin?Well, yes and no. Dr. Neal Schultz, MD , an NYC dermatologist and creator of BeautyRx by Dr. Schultz, says that sweat can actually be good for your skin. "It works as a moisturiser, it helps cleanse the pores, helps cool the skin, and even helps to kill bad bacteria on the skin — like staph — with its peptide called dermcidin," he says.But if you don't manage your sweat or take care of your skin, things can get slippery. "Underarms, buttocks, and foreheads get the sweatiest during the summer," says Dr. Elizabeth Tanzi, MD, founder and director of Capital Laser & Skin Care. But it isn't the salt in sweat that causes issues — it's what happens when that sweat sticks around on your skin for too long.The main issue is irritation. According to both derms, when sweat lingers in the folds of skin, it can promote chaffing, which leads to redness and discomfort. "The opening of the sweat glands can also get clogged, causing irritation like prickly heat," Dr. Tanzi says. Dr. Schultz agrees, and also stressed the fact that sweat can "wash away" sunscreen, leading to increased risk of UV damage.It's also worth noting that sweat can cause major odour due to bacteria. "There's no bacteria in sweat," Dr. Schultz says. "However, if the sweat is not removed with water or washed away, it can cause odour by promoting the growth of bacteria, which need moisture to grow. This is especially true in closed areas like the underarms and groin." Different body zones have different side effects, like bacne on a sweaty back or dermatitis on a sweaty foot. Ew.And the same applies to sweat luxuriating on your face. Sweat works like an activator, helping all the bacteria thrive, grow, settle into pores, and kick-start major flare-ups.The best course of action is to just ensure you're regularly wiping your sweat away. If you're breakout-prone, Dr. Tanzi suggests keeping glycolic acid or toning pads on hand. Also, be sure to shower thoroughly after a particularly sweaty day. There are plenty of things out there that make us sweat — but worrying about your skin doesn't have to be one of them.