What Should You Do If You Feel Dizzy While Running?

Whether you’re out chasing a sunrise tempo run or grinding through another sweaty session under the Bali sun…

That sudden wave of dizziness can stop you in your tracks—and yeah, I’ve been there. Mid-20K fasted run, no breakfast, brutal heat. One minute I was flying, next minute I felt like the world tilted sideways.

The good news? In most cases, dizziness during or after a run isn’t a medical emergency. As reported by Medical News Today, feeling dizzy post-exercise is usually harmless—it’s your body’s way of flashing a warning: “Hey, something’s off.”

Maybe you didn’t drink enough. Maybe you went too hard too soon. Maybe both.

In this guide, I’ll break down the difference between dizziness and lightheadedness (because yes, they’re not the same), unpack the top causes, and walk you through exactly what to do—whether it hits mid-run or afterward.

Let’s keep each other standing.

Dizziness vs. Lightheadedness: Know the Difference

Before you go full Dr. Google, figure out what you’re actually feeling. Runners often say they feel “dizzy,” but that can mean two very different things—and knowing which one you’ve got helps you respond smarter.

Lightheadedness feels like you’re about to faint—your brain’s getting low blood supply, and everything goes floaty or dim. But the world isn’t spinning.

Dizziness (aka vertigo) is different. That’s when it feels like the ground is spinning or tilting. Like you just stepped off a merry-go-round. Totally disorienting.

Quick breakdown:

According to MyHealth Alberta and the Mayo Clinic, lightheadedness often comes from things like dehydration, standing up too fast, or running on empty.

Dizziness tends to trace back to your inner ear or motion-related signals clashing with your visual system.

Either way: stop and deal with it. Pushing through just risks a faceplant.

Why Runners Get Dizzy – 8 Real Causes That Matter

Here’s the truth: dizziness during a run is your body raising a hand saying, “We’ve got a problem.”

Sometimes it’s just one issue—sometimes it’s a combo. Here’s the breakdown.

1. Dehydration & Electrolyte Loss

Sweat too much, and you’re not just losing water—you’re leaking sodium, potassium, and other key salts. Even losing just 1–2% of your body weight in fluids can mess with your balance. Add heat, and it gets worse.

I’ve made this mistake more times than I care to admit. Once during a long run in Bali, I pushed through the heat thinking water wasn’t urgent. Fifteen minutes later, I was dizzy, confused, and trying to find shade.

Johns Hopkins warns this kind of fluid loss can even lead to confusion and heat illness. Mayo Clinic backs that up—especially in humid conditions where sweat barely evaporates.

Pro tip? If you’re sweating buckets, you need more than just water—get electrolytes in too.

2. Low Blood Sugar (Fasted Running Gone Wrong)

Running hard without fuel is like trying to drive across town on an empty tank. You might make it a few miles, but at some point, your brain’s gonna say, “Nope.”

Symptoms of low blood sugar (aka hypoglycemia) include dizziness, weakness, and even confusion. And yes—dizziness is right there in the list.

If you’re skipping breakfast before your long run, make sure you’re at least used to it. Otherwise, that mile 10 wall? It’s not just fatigue—it might be a glucose crash.

3. Overexertion or Being Undertrained

This one hits newer runners and comeback runners the hardest.

When your fitness doesn’t match your effort, your body can’t keep up with oxygen and fuel demands—and your brain will feel it.

Dizziness from overexertion is legit (Medical News Today lists it right alongside nausea and weakness). When you feel that wave of wooziness mid-run, ask yourself: “Did I bite off more than I trained for?”

I’ve coached dozens of runners through this. You’re not broken. You just need to scale it back and build smarter.

4. Heat, Humidity & No Cooling Plan

Running under the tropical sun? Welcome to heat exhaustion land.

Your body’s working overtime to stay cool, which means blood shifts to your skin and away from your brain.

The Mayo Clinic says dizziness is an early red flag of heat exhaustion. I’ve had it hit fast in midday Bali heat—even on slower runs.

Johns Hopkins warns that without water, shade, or proper cooling, the body can crash into heat illness territory fast.

If you’re training in hot weather, start early, slow your pace, and drink before you’re thirsty.

5. Stopping Suddenly (Blood Pressure Drop)

Ever finish a hard interval, stop dead, and feel your vision tunnel? That’s post-exercise hypotension.

Blood pools in your legs when you stop moving fast, which can momentarily shortchange your brain’s supply.

MyHealth Alberta calls this a drop in blood pressure from quick changes in position.

The fix? Always cool down. Walk or jog easy for 5–10 minutes instead of crashing onto the sidewalk.

6. Bad Breathing Habits (Hyperventilation)

You’re sprinting. Breathing fast. Panicking a little. Suddenly your head tingles and spins.

That’s likely from over-breathing—blowing off too much carbon dioxide, which messes with how your brain gets oxygen.

I’ve been there, especially during speed sessions. Focus on slow, steady breaths: in through the nose, out through the mouth.

Sometimes it’s not lack of oxygen—it’s how you’re breathing.

7. Medical Conditions (POTS, Ear Problems, etc.)

Sometimes dizziness is a bigger clue.

Conditions like POTS (Postural Orthostatic Tachycardia Syndrome) can cause your blood pressure to tank and heart rate to spike when you stand. Inner ear issues can cause spinning sensations even if everything else is fine.

If this happens a lot—especially outside of runs—talk to your doctor. Better to check than guess.

8. Medication Side Effects

Don’t ignore the little print on the bottle.

Some meds—blood pressure pills, antihistamines, even antibiotics—can list dizziness or lightheadedness as a side effect.

If you’ve started something new recently, it might be worth connecting the dots.

Real Talk: Sometimes these causes team up.

No fuel, no water, midday sun? Been there. I once bonked so hard I forgot where I parked my motorbike.

Learn your warning signs and stay ahead of them.

How To Stop Dizziness From Ruining Future Runs

It’s a win to survive a dizzy spell — but it’s an even bigger win to never hit that wall again.

Here’s your go-to checklist to stay ahead of it:

Before You Run:

• Grab a pre-run snack if you’re going longer than 45 minutes. Something light and carby — banana, toast, or an energy bar 30–60 minutes out (The Running Week). It’ll help your energy stay steady and improve recovery.
• Hydrate early. About 16–20 oz of water an hour or two before you run (REI). If it’s sweltering, toss in a pinch of salt or a splash of electrolytes.
• Sleep like it matters. Poor sleep messes with everything, especially dizziness.
• Skip the booze and chill on caffeine. Both drain your system and dehydrate you before the run even starts.

During Your Run:

• Drink consistently. Don’t wait until you’re parched. REI recommends 5–10 oz every 15–20 minutes (REI). On hot or long runs, carry a bottle or hydration vest.
• Electrolytes are your friend. On anything longer or more intense, use a drink or salt tablets to stay balanced (Hopkins Medicine).
• Fuel up if it’s over 75–90 minutes. Start taking in carbs after the first hour — 30 to 60g per hour is a solid rule of thumb (The Running Week).
• Don’t ignore the warning signs. If you feel clammy, nauseous, or like you’re about to pass out — stop. I’ve had chills sneak up mid-run even in hot weather. That’s not “toughing it out” — that’s asking for trouble.

After Your Run:

• Cool down properly. Walk or jog for 5–10 minutes before stopping. Helps your blood flow adjust and prevents sudden drops in blood pressure.
• Rehydrate and refuel. Especially if you lost a lot of sweat — aim for 16–24 oz of water per pound lost (REI). And follow it with a mix of carbs and protein.
• Get salty. If you sweat like crazy, eat something salty post-run — salted nuts, sports drink, whatever works.
• Check your heart rate. If you just finished a hard workout, sit still until your heart rate comes down before moving around.

When you build this routine into your training, your body starts to recognize the rhythm — and you’ll notice warning signs faster if something’s off.

What’s your go-to fuel before a long run? Ever had a close call with dizziness mid-run?

Tropical Running – The Brutal Combo of Heat & Humidity

Running in Bali taught me that heat isn’t just uncomfortable — it’s dangerous.

It’s like dragging a furnace behind you in the form of sweat and sun. And it spikes your risk of dizziness fast.

• You lose fluids like crazy. Even at slow paces, your body dumps sweat. Johns Hopkins says to do your runs in the cooler hours and hydrate like it’s your job. Personally, I slam a tall glass of water first thing in the morning just to prep for a 7 AM jog.
• You need more than water. Salt, potassium, magnesium — they all matter when you sweat hard. In cooler climates, plain water might cut it. In the tropics? You’ll cramp and stagger without electrolytes.
• Slow it down. A pace that feels fine in the shade can cook you in the sun. I’ve learned to adjust — if I planned to hit 6:00/km, in 90-degree weather I might run 6:30 or even 7:00. Better to finish feeling good than pass out trying to “stay on pace.”
• Timing is everything. I don’t touch long runs after 8 AM during Bali’s hot months. Sunrise or post-sunset only. Even then, I still feel like I’m melting some days.

If you get chills mid-run — or goosebumps when it’s hot — stop.

That’s a red flag your core temp is spiking. The Mayo Clinic warns that heat exhaustion can come on fast, and the symptoms mimic overexertion: dizziness, nausea, brain fog, weird heartbeat.

Respect the heat, or it’ll humble you.

What’s your heat strategy? Are you the early riser or sunset runner?

Treadmill Dizziness – The Weirdest Kind

Ever stepped off the treadmill and felt like the floor was moving?

That “boat legs” feeling is real. And it’s not just in your head — your brain and balance are genuinely confused.

Treadmills mess with your sensory system. Your body’s in motion, but your surroundings aren’t. That disconnect throws off your inner ear and balance centers.

According to Medical News Today, machines like treadmills and ellipticals are common triggers for post-workout dizziness.

One runner on Reddit nailed it: “I got off the treadmill after 40 minutes, and the room was spinning.” Been there.

Here’s what I’ve found helps:

• Cool down on the treadmill. Don’t go from sprinting to full stop. Ease the belt down and walk for a minute before hopping off.
• Grab the rails if needed. No shame. Balance is balance — better to steady yourself than faceplant on the gym floor.
• Focus your gaze. Staring at a TV or mirror while running makes things worse. Keep your eyes on a fixed point ahead to help your body stay grounded.
• Sit down if it hits hard. If the world starts tilting, take a seat and let it pass.
• Know your options. If treadmill dizziness keeps happening, try outdoor runs or switch machines. Not everyone adjusts the same way.

The good news? Most runners adapt after a few treadmill sessions (Reddit).

Just take it seriously and ease your way through the transition.

When Dizziness Isn’t Just About Skipping Breakfast

Most dizzy spells during a run? They’re usually tied to fuel or heat. Not always a big deal.

But sometimes, your body’s waving a serious red flag.

If you feel dizzy and also notice any of this stuff, don’t push through — stop, sit down, and get help:

• Chest pain or pressure, especially paired with the dizziness
• A weird fluttering heartbeat or pulse that feels way off
• Numbness or weakness down one side of your face or body
• Slurred words, fuzzy vision, or flat-out confusion
• Fainting — not “I almost fainted,” but full blackout
• A nasty headache or seizure
• Body temp shooting past 104°F (40°C), especially during a hot run

These aren’t minor annoyances. These could be signs of heart arrhythmias or even neurological events.

According to Heart Foundation, intense exertion can trigger arrhythmias, and that alone can cause dizziness or make you pass out. Same goes for a mini-stroke (TIA) — sudden dizziness or loss of balance can be a warning sign.

So yeah — don’t try to “tough out” symptoms like these. If your gut says something’s off, believe it.

When It’s Happening Too Often

Even if you’re not fainting or seeing stars, frequent dizzy spells aren’t normal.

If you’re feeling off regularly — like, “Whoa, why do I keep getting lightheaded after 20 minutes?” — go get checked.

A basic physical might be all it takes: blood pressure, blood sugar, iron levels, or maybe an EKG to rule out heart stuff.

Some folks I’ve coached turned out to have low iron or thyroid issues. One runner on Reddit mentioned getting shaky and out of it halfway through workouts — later learned she was dealing with anemia and early-stage diabetes.

Not the kind of surprise you want mid-run.

The truth? It’s way better to find out it’s just a bad week of training than to ignore something serious.

Don’t guess — find out.

For New Runners Dealing With Dizzy Spells

Hey, if you’re new to this and had your first “woah, I feel dizzy” moment — welcome to the club.

It doesn’t mean you’re broken. It just means your body’s learning.

Here’s what I tell my coaching clients when dizziness hits mid-run:

• Stop right away. Don’t walk it off. Sit or lean against something in the shade.
• Sip water slowly — bonus points if it has salt or electrolytes.
• Get those legs up. Even the elites lie down after brutal races. You don’t need to act tough.
• Think it through. Did you eat enough? Was it too hot? Did you skip hydration? Learn from it.
• Be kind to yourself. Dizziness isn’t betrayal — it’s a signal. Respect it.

And hey, if it’s your first dizzy run, talk about it. Tell a friend. Post in a running group.

You’ll be shocked how many of us have stories just like it.

The runner who learns how to handle red flags is the one who sticks with this sport for life.

As one coach said: the smartest runners aren’t the fastest — they’re the ones still running strong ten years later.

Quick-Answer FAQs

Q: Why do I get dizzy after running in the heat?

A: Simple: your body’s trying to cool down, which pulls blood away from your brain and muscles. Add sweat loss and salt loss, and your blood pressure tanks. Result? Dizziness.

Hydrate before, during, and after. Take salt or electrolytes, especially if you’re running in high temps.

Q: Is it okay to run fasted?

A: For easy 20–30 minute jogs, sure. But anything longer? Eat something.

Research shows even a small pre-run snack (like a banana or slice of toast) can make you feel and run better.

If you’re dizzy after fasted runs, that’s your answer — fuel up next time.

Q: Can dehydration make me faint?

A: Absolutely. Lose too much fluid, and your blood pressure crashes.

You’ll start with thirst, maybe dry mouth, dark pee — then it gets serious.

If someone faints from heat or dehydration, call for help. Only fix? Fluids and salt.

Q: How much water and electrolytes do I really need?

A: General rule: 16–20 oz (~500 ml) two hours before long runs, then 5–10 oz (~150–300 ml) every 15–20 minutes.

If it’s hot, use a sports drink or add electrolytes.

Post-run, rehydrate with 16–24 oz (~500–700 ml) for every pound you lost in sweat.

Q: Is it safe to run the day after dizziness?

A: If you’re feeling 100% back to normal, a slow shake-out run or some cross-training is fine.

But if you passed out or felt really off, skip a day or two. No workout is worth the risk.

Fuel well, rest up, and come back smarter.