How Do You Know If You Need Electrolytes? 5 Signs to Look For

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Electrolytes are essential for fluid balance, muscle function, and athletic performance, but how do you actually know when you need them?

Although electrolytes are trending on social media, you don’t actually need them as often as you think. But there are times when electrolyte replacement is necessary for performance.

So how can you recognize the signs of electrolyte imbalance before it impacts your workouts or recovery?

In this article, we’ll break down 7 clear signs you may need electrolytes—and when water alone isn’t enough.

What Are Electrolytes?

Electrolytes are minerals like sodium, potassium, magnesium, and calcium. These charged particles help your body:

  • Maintain fluid balance
  • Contract and relax muscles
  • Send nerve signals
  • Regulate blood pressure and pH levels

The body tightly regulates its electrolyte balance. Certain electrolytes live inside the cell, while others live outside the cell. An electrolyte imbalance can cause fatigue, dehydration, cramping, weakness, tingling, or confusion–none of which are pleasant during your workout!

When Do You Need Electrolytes?

You lose electrolytes through sweat, especially during longer or more intense workouts. If those losses aren’t replaced, you may experience unpleasant side effects, and performance can take a hit.

Therefore, you need to replenish electrolytes in these situations:

  • during a sweaty workout that lasts longer than 60 minutes
  • during a workout in a hot and humid climate
  • if you are a heavy sweater (you sweat through your clothes or have chalky white spots on your skin after exercise)

If you don’t replenish electrolytes in these situations, you will become dehydrated and your performance will suffer.

Unsure if these situations apply to you? Here are 5 telltale signs that you probably need electrolytes during a workout:

1. You Get Muscle Cramps Mid-Workout

Frequent or unexpected muscle cramps are a major red flag, and usually a sign of an electrolyte imbalance. While dehydration may play a role in muscle cramps, being low sodium, potassium, or magnesium is a more likely culprit.

If you’re cramping up during a run, ride, or strength session, it might be time to add an electrolyte supplement before or during your workout.

2. You’re a Heavy Sweater

Some people naturally sweat more than others. These are signs you may be a heavy sweater:

  • Salt streaks (white dust) on your clothes or skin
  • Dripping sweat early into a workout

If this sounds like you, you’re likely losing a lot of electrolytes during exercise, and you need to replenish them to feel and perform your best.

3. You Feel Dizzy or Lightheaded After Exercise

Post-exercise dizziness, lightheadedness or a headache is often a sign of dehydration. The tricky part here is that these signs may appear if you didn’t take in enough fluid OR electrolytes. These symptoms are more prevalent after long workouts or training in hot weather, which is when electrolyte losses usually occur.

If you are hydrating frequently during exercise (taking sips of water every 15-20 minutes) and you still experience dizziness, lightheadedness or headaches, then you may need to incorporate electrolytes into your hydration routine.

4. You’re Training in Hot or Humid Conditions

Heat and humidity increase your sweat rate, which means greater fluid and electrolyte losses, even in short sessions. Plus, humidity prevents sweat from evaporating off the skin, which is how the body cools down. So, you may feel extra hot and parched in high humidity situations.

If you’re exercising outdoors in summer, you’re more likely to need electrolytes before, during, and after your workouts.

5. You’re Fatigued or Struggling to Recover

If you’re practicing good post-workout recovery nutrition and taking in plenty of water during exercise, but you still feel worn down or sore after workouts, an electrolyte imbalance could be the missing link. Sodium, magnesium, and potassium all play roles in energy metabolism and muscle repair.

A lack of electrolytes can hinder your recovery and leave you dragging through your next session.

Quick Self-Check: Do You Need Electrolytes?

Here’s a quick checklist. If you say “yes” to 2 or more, adding electrolytes to your routine is a good idea:

  • I sweat a lot or work out in the heat
  • I get muscle cramps during or after workouts
  • I feel lightheaded or dizzy after exercise
  • I’m constantly thirsty even when drinking water
  • I have headaches or fatigue post-exercise
  • I train for more than 60 minutes at a time

If you did not say yes to two of more items on the list, hydrate with just water.

When Should You Take Electrolytes: Before, During, or After Exercise?

Once you realize you do need electrolytes, timing matters. Here’s how to decide when to take them based on your workout and sweat level:

Before Exercise:

Take electrolytes before your workout if:

  • You train in the morning without eating much
  • You’re doing a long or intense workout (60+ minutes)
  • It’s hot or humid outside
  • You sweat heavily or are prone to cramping

How: Sip an electrolyte drink 30–60 minutes beforehand to top off your fluid and sodium levels.

During Exercise

Take electrolytes during your workout if:

  • Your workout lasts longer than 60–90 minutes
  • You’re doing endurance events like long runs or bike rides
  • You sweat heavily or see salt on your skin/clothes

How: Use electrolyte tablets, powders, or drinks every 30–45 minutes, especially during races or long runs.

After Exercise

Take electrolytes after your workout if:

  • You feel depleted, lightheaded, or nauseous
  • You trained for a long time or in hot conditions
  • You’re doing two-a-days or training again soon

How: Replenish with electrolytes and water alongside your post-workout meal or recovery snack.

Pro tip: For many athletes, especially runners and those on plant-based diets, a combo of before, during and after is the best approach to stay hydrated and recover quickly. Try different combinations to see what works best for you.

How to Replenish Electrolytes the Smart Way

Most people lose around 300-500 milligrams of sodium for pound of sweat. You can calculate your sweat rate to determine fluid losses during a workout and try to figure out how many electrolytes you may need.

I advise clients to pay attention to their body and how they feel during and after exercise to determine if you need electrolytes.

Look at the color of your urine to assess hydration status. If it’s pale yellow, you are properly hydrated and probably don’t need electrolytes. If it’s darker yellow, you’re dehydrated and may need electrolytes or more water.

If you opt for an electrolyte supplement, choose one that has 200–500 mg of sodium per serving and includes potassium and magnesium for recovery.

Try powders, tablets, or electrolyte drinks like Nuun, LMNT, or Ultima, and be sure to time your intake around your most intense workouts. Or eat foods that have electrolytes.

Final Thoughts

Electrolytes are crucial for performance, hydration, and recovery, but you only need them in certain circumstances. If you’re noticing signs like cramping, dizziness, or sluggish recovery, it’s time to re-evaluate your fueling plan.

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I’m Natalie Rizzo, an NYC-based Registered Dietitian.

My mission is to help everyday athletes fuel their fitness with plants.

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