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Common Vasovagal Syncope Triggers

Syncope is fainting or what is loosely termed passing out. In many cases, you experience symptoms like nausea, lightheadedness or dizziness, blurred vision, warmth, and sweaty palms before fainting referred to as pre-syncope. The Woodlands syncope results when blood flow to the brain is affected, impacting the latter’s functionality. A serious cardiovascular condition could cause fainting, referred to as cardiac syncope. In most cases, it is caused by certain triggers known as vasovagal syncope. Below is a glance at some of the common vasovagal syncope triggers.

Hunger and thirst

Hunger or failure to eat enough food can result in low blood sugar. This is more common in those with diabetes. As the blood sugar drops, you can easily pass out as the brain strives to preserve more energy to function normally. The situation is worse when you are dehydrated. If you feel thirsty, you are already dehydrated to some level. Dehydration leads to a drop in blood pressure, which can cause vasovagal syncope. Drinking enough fluids helps maintain better blood pressure and blood volume, making it easier to avoid vasovagal syncope.


If your occupation requires you to stay in one position for an extended period, mostly standing, you can easily faint. This is because such posture causes your blood to pool away from the brain. This emphasizes the need to take regular breaks or simply change the posture. Besides staying put for long, you can pass out if you stand up too quickly from a sitting or sleeping position. This happens because the sudden move does not allow enough blood to reach your brain.

Strong emotions

Strong and often sudden strong emotions like anger, fear, anxiety, or stress can cause vasovagal syncope. The emotions impact your nerves which helps control blood pressure. This means the blood does not flow well to replenish the brain for normal functioning, resulting in passing out.

Besides the emotional load, pain, a sensory and emotional experience, can cause syncope. Severe pain affects the vagus nerve. The pain stimulates the vagus nerve, which impacts various aspects, including heart rate, digestion, and respiratory rate. Overstimulated vagus nerves can cause your blood pressure or heart rate to drop too much or suddenly, resulting in fainting.

Over-exertion or straining

Physical exertion, for example, working out too much in hot weather, can lead to dehydration, which results in a drop in blood pressure, consequently, passing out. In other cases, you could strain, such as when struggling with bowel movements. The straining can result in a slow heart rate and a drop in your blood pressure, causing you to faint.

Medications and drugs

Certain medications, including some blood pressure medicine, can lower the pressure beyond what you need, resulting in pre-syncope or even passing out. Drugs, such as excessive alcohol, can affect your brain chemistry, resulting in passing out, commonly known as blacking out.

Triggers like the sight of a needle for a shot or blood are common and not considered serious. If you experience pre-syncope, it is recommended that you lie down, which can even help avoid fainting as blood flow to the brain is restored. Contact Northwest Houston Heart Center today for more on syncope, diagnosis, and treatment.

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