How To Know If Your Sweat Is Too Salty

Finding Out Is What You Thought It Was

Sweat Is Not The Same For Everyone And The Differences Matter

NOTE: This salty story was originally published in ‘Run Powered By Outside’ and written by Danielle Zickl on August 12, 2025. But we did the illustration.

Whether you’re training for a 5K or logging countless miles in preparation for a marathon, all runners share one thing: sweat. While we’re all subject to beads of perspiration dripping down our foreheads, sweat isn’t the same for everyone. Some runners hardly notice it, while others finish a run absolutely soaked. And then there are the salty sweaters: runners who have visible white streaks and can feel the crunch of salt and sweat on their clothes and skin. If that sounds like you, your sweat is likely high in sodium.

The good news is that sweating salt is completely normal. But it may influence how you fuel and hydrate your workouts. Here, Emilie Burgess Horvath, a registered dietitian for USA Track & Field and the Hospital for Special Surgery, fills us in on the details about why sweat is salty, signs that indicate you have predominantly salty sweat, and how that affects your run preparation.

Why Is Your Sweat Salty Anyway?

You sweat to regulate your body temperature, Burgess Horvath explains. When you exercise, your core body temperature rises, and sweating allows your body to cool itself.

Understanding how much you sweat and what’s actually in your sweat can help you tailor your hydration and fueling strategies to prevent dehydration, hyponatremia (when the level of sodium in your blood is too low), and fatigue during your training, Burgess Horvath explains.

Sodium concentration in sweat can vary from person to person—about 200 milligrams per liter up to 1,000 milligrams per liter, she says. It depends on factors like age, sex, aerobic fitness, hydration status, and environmental conditions, according to a 2022 study in the Journal of Applied Physiology.

“This variation means that some athletes will lose a lot more electrolytes—not just sodium—than others, and simply drinking water isn’t going to be enough to maintain that electrolyte balance,” Burgess Horvath says. “So knowing your sweat profile—salty sweater versus light sweater—can guide decisions around electrolyte intake before, during, and after exercise, fluid volume needs day to day, and also any recovery practices.” (More on this later!

4 Signs You’re a Salty Sweater

You’ll typically be able to tell if your sweat is predominantly salty based on the following indicators, according to Burgess Horvath:

• Your sweat tastes salty: “One of the most common signs I usually see in practice is definitely the salt taste within your sweat, like when it hits your lips, during exercise,” Burgess Horvath says.
• Your sweat burns your eyes: It’s not the run making you cry; it’s the salt from your sweat getting in your eyes. (Granted, this could be sunscreen or mascara, so look out for the other signs.)
• You notice white stains on your clothes: Look for white chalky stains or crust on your workout clothes, like your shirt or the inside of your hat, as another sign your sweat is majorly salty, according to Burgess Horvath. You’ll likely be able to see white salt lines on your skin post-run, too.

• Frequent Muscle Cramps: Muscle cramping, especially in hot and humid conditions, is another signal your sweat is salty, Burgess Horvath says. Losing sodium (an electrolyte) through your sweat causes your muscles to tighten and cramp. (It’s important to note that muscle cramps could also be the result of many other factors, like dehydration, overexertion or fatigue, circulatory issues, medications, and other medical conditions, so it’s important to chat with your doctor if you experience them regularly.)

Losing too much sodium through your sweat could lead to health issues like nausea and vomiting, headache, fatigue, muscle weakness or cramps, confusion, irritability, and even seizures or coma, per the Mayo Clinic. Burgess Horvath explains that carefully planning your hydration and fueling strategy before, during, and after a run is key to not losing too much sodium. In an ideal world, you’d consult with a sports dietician to create a strategy tailored to your needs. But these tips can help you with a basic fueling plan.

Burgess Horvath emphasizes the importance of carbs because they enhance fluid absorption and promote better fluid retention. She suggests consuming 30 to 60 grams of carbs about 45 minutes before your run. (A banana, for example, has about 30 grams of carbs.) During your run, she recommends getting at least 60 grams of carbs per hour. Post-run, she says to aim for a 2-to-1 ratio of carbs to protein—20 grams of protein with 40 grams of carbs, for example.

That’s right, this is permission to eat more salt. Burgess Horvath recommends consuming sodium-rich foods, like pretzels, or electrolyte sports drinks that contain sodium before, during, and after your runs. The current dietary guidelines for Americans recommend adults get no more than 2,300 milligrams of sodium a day. However, athletes who are heavy sweaters and exercising multiple hours a day—say, running a four-hour marathon—may need up to 3,500 milligrams of sodium per day, according to an article in Current Sports Medicine Reports.

Finally, it’s important to stay on top of your hydration—not just on the days you go for a run, but day in and day out. “You don’t want to be playing catch-up when training or competition comes around,” Burgess Horvath says.

An easy way to check your hydration status throughout the day is by assessing your urine color, she says. The darker and more yellow your urine is, the more dehydrated you are, according to a 2020 article in Frontiers Nutrition. On the other hand, having lighter and clearer urine indicates you’re hydrated.

“The goal is to replace, but to not exceed, fluid losses,” Burgess Horvath says. “An average you might hear is to not lose more than 2 percent of body weight during training or exercise. So using sports drinks or hydration supplements, with adequate sodium and carbs, can be a great way to help with that.”

A general rule of thumb is to stay hydrated with water if your runs or other workouts are less than 45 minutes long, and turn to electrolytes for anything longer, Burgess Horvath says. And you can get a general sense of how much fluid you’ve lost during your run by weighing yourself before and after. Make sure to rehydrate with fluids and electrolytes to replace around 120 to 150 percent of the fluid that you lost during exercise, including salty foods. And that could just be your regular post-run meal—having something like soup or putting table salt on your meal that has that 2-to-1 ratio of carbs to protein.

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