6 Reasons Why You May Feel Lightheaded After a Workout, According to Experts

You get off the bike after a challenging indoor cycling session or finish up a long run, and suddenly a strange, unpleasant feeling hits: You’re faint and a little woozy, like you might pass out. Feeling lightheaded after a workout can be uncomfortable, but the good news is that it’s not uncommon and usually isn’t caused by anything too serious. 

“The body is being stressed in many ways during exercise,” says Frank B. Wyatt, a professor in the department of athletic training and exercise physiology at Midwestern State University. One way this stress can manifest is in post-workout lightheadedness, particularly if you’ve pushed yourself a little harder than usual.

Still, lightheadedness after exercise shouldn’t be ignored, since it could be a sign you need to change up something about your workout routine, such as drinking more water or taking a rest day. And although it’s rare, lightheadedness can be caused by a more serious health condition, so it’s important to speak to your doctor about new symptoms you’re experiencing— especially if they don’t go away. Read on for everything you need to know.

Feeling Lightheaded vs. Dizzy After a Workout

People often use “lightheaded” and “dizzy” interchangeably, but these terms have different meanings. “Lightheadedness is more of a feeling like you’re going to faint or pass out, whereas dizziness is the sensation that everything around you is spinning,” explains John Luksch, DO, a primary care and sports medicine physician at Rothman Orthopaedics in the Philadelphia area who serves on the board of directors for the American Osteopathic Academy of Sports Medicine (AOASM). 

Feeling truly dizzy after a workout, which is also known as vertigo, would usually be considered a little more concerning, experts say, since dizziness can be caused by conditions such as inner ear disorders or infections, migraine, or even stroke. Lightheadedness, meanwhile, can often be easily explained by an environmental cause, such as not drinking enough water. 

Still, it’s difficult to say for certain whether one is more serious than the other without consulting your doctor. Depending on how you’re feeling in the moment and what other symptoms you’re experiencing, lightheadedness can warrant a closer look from your physician.

Is It Normal to Feel Lightheaded After a Workout?

It’s not uncommon to feel lightheaded after a workout, according to experts. But that doesn’t mean you should dismiss a lightheaded feeling as no big deal. 

“People sometimes confuse ‘normal’ and ‘common,’” Dr. Luksch says. “A lot of people, very commonly after they do a workout—particularly a hard one—feel lightheaded. Is it normal? Probably not. But it’s probably pretty common.”

In other words, there’s most likely a not-so-alarming explanation for the lightheadedness you’re experiencing, such as dehydration or simple overexertion. (See more potential causes below.) But this isn’t the way you’re supposed to feel after exercising, so it’s absolutely worth looking into with your doctor.

Why You Feel Lightheaded After Working Out

So what actually makes you feel lightheaded after exercising? Most likely, the sensation you’re experiencing can be easily explained and fixed. But as mentioned, lightheadedness can occasionally be a sign of something more serious, which is why it’s so important to check in with your practitioner about your symptoms. “There are a lot of reasons why it can happen, some more concerning or dangerous than others,” Dr. Luksch says. 

With that in mind, here are some of the most common causes of lightheadedness after a workout, according to experts:

1. Overexertion

Pushing yourself too hard during exercise—such as by repeatedly lifting weights that are too heavy for you, or exercising for too long or too many days in a row—can stress your body and result in lightheadedness at the end of a workout. This can also happen if you’ve taken a break from exercise and don’t give yourself a chance to ease back in. “If you’re coming off two weeks where you weren’t doing anything—maybe you were on vacation or sick—and you’re all of a sudden jumping back in at the same intensity and same amount that you were doing before, that might not be the best thing to do,” Dr. Luksch says.

2. Dehydration

One of the simplest reasons why you might feel lightheaded after a workout is that you weren’t well hydrated. Not drinking enough water throughout the day—particularly if you’re exercising outside and it’s hot and humid—is a recipe for dehydration. “If you feel lightheaded after a workout, first ask yourself: Am I drinking enough water? Did I eat a nutritious and filling meal before?” says Jay W. Lee, MD, who serves on the board of directors of the American Academy of Family Physicians.

The human body is about 60 percent water, according to the US Geological Survey, and hydration impacts nearly all of our bodily functions. If you haven’t been consuming enough fluids, your blood volume can go down, which can lead to lightheadedness.

3. Low Blood Sugar

Also called hypoglycemia, low blood sugar levels can cause lightheadedness after a workout. “The brain subsists primarily on glucose, and as we exercise we deplete our glucose levels,” Wyatt says. “This commonly leads to hypoglycemia, or low blood glucose levels, both during and after exercise.” In addition to experiencing lightheadedness or dizziness, you might have low blood sugar if you feel nauseous, irritable, shaky, or like you have an irregular or fast heartbeat.

People who have type 1 diabetes, a condition in which the pancreas doesn’t make enough insulin, can frequently experience hypoglycemia, such as after taking too much insulin. But other conditions and certain medications can cause it, too. If you don’t have diabetes and are experiencing the symptoms above, let your doctor know so you can get your blood sugar levels checked.

4. Blood Pressure Changes

If you’ve ever sat or stood up quickly and suddenly felt lightheaded and woozy, you’ve experienced something called orthostatic hypotension, a condition brought on by blood pressure fluctuations that can cause lightheadedness. “There is a constant adjustment of the body’s blood pressure when we change body positions, such as by standing,” Wyatt says. After a workout, you might notice this if you were exercising on a mat or indoor bike and then quickly changed positions.

Orthostatic hypotension can sometimes occur randomly and be mild, or it can be triggered by a one-off cause like overexertion or overheating. But depending on how frequent and severe your symptoms are, your doctor may recommend medication. 

5. Medications

Some medications can cause lightheadedness—particularly those that work to lower your blood pressure, Harvard Health Publishing notes—and the effects can be especially pronounced after you’ve exerted yourself during a workout. If this is the case for you, tell your doctor about the side effects you’ve been experiencing: There may be a different dosage that helps you feel less woozy or another medication you can take instead. 

6. Heart Conditions

More than likely, lightheadedness after a workout is nothing to be too worried about. But rarely, feeling woozy and faint after exercise can be a sign of a heart condition. “Lightheadedness can happen if you have any kind of arrhythmia or abnormal heartbeat,” Dr. Luksch says. “Or, if you have a murmur, an abnormal sound that you can hear when you listen to somebody’s heart, which can indicate blocking or narrowing of blood passing through the chambers of the heart through the rest of the body.”

If your lightheadedness is being caused by a heart condition, you might also experience a fluttering or pounding feeling in your chest, dizziness, sweating, and anxiety. Bring these symptoms up to your doctor right away if you’re experiencing them. That’s especially important if you’re also feeling chest pain, shortness of breath, nausea, and arm pain, which can be signs of a heart attack.

If you have a wearable fitness tracker (such as an Apple Watch® or a Fitbit®), you might also check the data after your workout. “These monitoring devices can check for things like heart rate and can tell you if you’re in a normal heartbeat,” Dr. Luksch says. While they can’t diagnose or rule out a heart condition—you should still consult your doctor regardless of what the data says—they may help raise possible red flags. “For example, if your device shows that you’re in an abnormal heartbeat and you’re oxygenated enough, that’s concerning,” he says.

What to Do If You Feel Lightheaded After a Workout

If lightheadedness hits you suddenly during or at the end of a workout, the first thing you should do in the moment is stop and give yourself a chance to rest.

Next, take a sip of water and let yourself cool down. “Take deep breaths, rest, and take a sip of water,” Dr. Lee says. “I also recommend placing a cold cloth around the forehead or neck, which can help alleviate nausea and dizziness. This will help slow your heart rate [and] get your blood sugar back to normal levels.”

Because lightheadedness can also sometimes be caused by hypoglycemia, eating or drinking something that’ll restore your blood sugar levels is also important. For a quick boost, Wyatt recommends chocolate milk: “It contains carbohydrates, protein, and chocolate, a photochemical that facilitates endogenous release of antioxidants,” he says. “These help in the recovery process.”

How to Prevent Lightheadedness After Workouts

Lightheadedness after exercise can’t always be avoided, such as if your doctor determines that you have one of the health conditions above. But if the lightheaded feeling you’re experiencing is caused by overexertion, dehydration, or low blood sugar levels, there are some strategies you can try to prevent it from happening in the future. Here’s what experts recommend:

1. Hydrate Before, During, and After Workouts

“Hydration is really important,” Dr. Luksch says. The US National Academies of Sciences, Engineering, and Medicine recommends about 15.5 cups (or 3.7 liters) of total fluids per day for men and about 11.5 cups (or 2.7 liters) per day for women, though you might need a little more if you’re exercising a lot.

2. Eat Before Exercising

To prevent feeling lightheaded after exercise, don’t go into your workout on an empty stomach. “Eat some food approximately three hours pre-exercise, generally in the form of a carbohydrate,” Wyatt advises. Research has shown that carbs can be particularly beneficial in helping you exercise for longer and avoid lightheadedness.

3. Consider If You Need a Rest Day

There is such a thing as exercising too much. In addition to post-workout lightheadedness, other signs you’ve been pushing yourself a little too hard include sore muscles, a feeling of heavy limbs, mood swings, and trouble performing at the same level of intensity, per the National Library of Medicine.

4. Ease Back Into Things

If you’ve taken time off exercise for any reason, give yourself a chance to get back up to speed. That might mean opting for slightly easier workouts for a few days while you ramp up to the intensity level you were doing previously (for example, a 20-minute ride rather than diving right back into your favorite 60-minute class). “During a workout, breathe normally, avoid overexerting your body, and gradually increase the intensity of workouts,” Dr. Lee says. “Don’t go from zero to 100.”

5. Make Sure You Warm Up

If you’re in a rush, skipping your warm-up can feel like an easy way to save time. But giving your body a chance to adjust to exercise mode is critical, experts say. “Start easy with a warm-up and always follow the workout with a cooldown,” Wyatt says. “Cooling down after every workout helps normalize blood pressure fluctuations,” he adds.

When to Talk to Your Healthcare Practitioner

If you suspect your lightheadedness is caused by dehydration and drinking more water helps ease symptoms, you may not need to see a doctor. But if lightheadedness doesn’t go away, is accompanied by other concerning symptoms (such as dizziness, pressure in your chest, or a feeling like you can’t get enough air), or it’s occurring even when you’re not exercising, get in touch with your practitioner right away.

This is especially important if your symptoms seem severe and persistent, but you should feel empowered to consult your doctor about minor lightheadedness, too, Dr. Luksch says. “Maybe it’s not the sort of thing that needs a big, extensive workup, and maybe what you’re feeling is to be expected,” he says. “But if it’s something that’s giving you any kind of degree of concern or worry, then reaching out and at least asking your doctor about it is never a bad idea.”

The Takeaway

Lightheadedness after a workout can make you feel faint or woozy, and it’s a little different from dizziness, in which you may feel unsteady and like the room is spinning. Chances are good that the lightheadedness you’re experiencing can be easily explained by a not-so-serious cause, such as dehydration or working out a bit too hard. But because lightheadedness can also be associated with more concerning health conditions, it’s always a good idea to check in with your doctor, particularly if it persists. Make sure to mention any other symptoms you may be experiencing, too, such as chest tightness or nausea.

This content is for informational and educational purposes only and does not constitute individualized advice. It is not intended to replace professional medical evaluation, diagnosis, or treatment. Seek the advice of your physician for questions you may have regarding your health or a medical condition. If you are having a medical emergency, call your physician or 911 immediately.