Why You Get Dizzy or Lightheaded When You Stand Up

Woman holding her head
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If you exercise often and are in good shape, you might occasionally experience dizziness and lightheadedness when you stand up quickly. This is generally nothing serious. But occasionally, these symptoms may be due to a more serious issue, so it's important to understand the causes of occasional dizziness.

Post-Exercise Dizziness

Cardiovascular exercise makes your heart stronger, and a stronger heart has a larger stroke volume. That is, the amount of blood pumped out during each beat is greater, so the heart doesn't have to beat as often. A slow pulse rate is an indication of a strong, healthy heart.

However, a slow heart rate can sometimes lead to dizziness when you change position. You may feel dizzy after exercise as your heart slows down drastically. A longer cool-down period and a slow and steady walk should get you back on track as the dizziness dissipates.

Low Blood Sugar

Low blood sugar can also cause dizziness. If you skip meals, low blood sugar can lower your mood and energy and result in lightheadedness. Keep your blood sugar balanced by eating meals and snacks regularly, usually every three hours, to stave off dizziness.

If you are eating regularly and not skipping meals yet still experiencing signs of low blood sugar (such as shakiness, sweating, headache, or fast heartbeat), a more serious condition associated with low blood sugar could be a possibility. These include diabetes or hypoglycemia.

Low Blood Pressure

When you stand up quickly, gravity pulls blood from your brain towards your feet, and blood doesn't return to the brain until the next heartbeat. With a slow pulse, this takes a second or two, and that is enough time to feel the lack of oxygen in the symptom of lightheadedness or dizziness.

It is also related to something called postural hypotension, which is more common in older adults. This results from a decrease in blood flow to the brain due to a drop in blood pressure upon standing up.

If you have a slow pulse (50 or less) and experience dizziness when standing up, try getting up more slowly and see if that solves the problem.

Dehydration or Overheating

Dehydration is another common cause of dizziness. Insufficient water in the body can cause blood flow to slow down. Dehydration undermines the body's ability to process normal functions, and because blood is 80% water, blood pressure is lower if you're dehydrated.

If your urine is dark yellow, has a pinkish tint like chardonnay, or is orange, you may be dehydrated. Stop exercising and drink water or a sports drink.

Overheating (hyperthermia) due to exercise, hot weather, or medications can also cause dizziness. Overheating can come on suddenly or develop over a longer time period.

Either way, if you sweat profusely, or feel like you have a fever not associated with cold or flu symptoms, get help immediately. Stop exercise, move to a cooler environment, and use cold compresses on your neck. If due to hot temperatures, you may be developing heat exhaustion or heat stroke.

Inner Ear Issues

If the room seems to be spinning or you feel like you are moving while standing still, you may have an inner ear issue. Called vertigo, this is a serious condition that needs medical attention to correct. Inner ear changes due to age, ear infection, or sudden changes in ear fluid are the major causes of vertigo.

When to See a Doctor

As long as your dizziness occurs only occasionally, you don't need to worry. However, if you have constant and severe dizziness, you should see a doctor who can rule out an underlying condition such as an irregular heartbeat, anemia, ulcers, anxiety, or other medical conditions.

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