You get up one day, or get up from a chair, or just stand there and you faint.

Fainting (or by its medical name, syncope), is one of the most frightening problems for patients, but it’s also a common problem. 1-3% of visits to the ER are due to fainting each year.

In this article, we will cover the various reasons behind fainting. As with our other solutions pages, this data is not meant to replace a doctor’s advice, and only serves as a reference.

Definition

Syncope (or fainting) is defined as a sudden, brief loss of consciousness caused by a decreased blood flow to the brain.

Syncope

Causes

The causes for syncope can be divided into 5 groups, as can be seen in this diagram:

1. Vasovagal:

In spite of the numbers above, this is the type most commonly seen in the hospital.
This type occurs when the body over-reacts to certain triggers. Examples of these triggers include:

a. The sight of blood, or having your blood drawn
b. Standing for a long time
c. Exposure to heat
d. Pain
e. Emotional stress
f. Fatigue
g. During normal body functions such as coughing, urinating, swallowing or straining in the toilet.

This is caused because the vagus nerve, a part in our nervous system which helps regulate our blood pressure and heart rate, malfunctions. This causes our heart rate to slow in response to the above triggers, and the veins in our legs to widen, causing blood to pool in your legs. Both of these come on the account of blood coming to the brain, causing the brain to get less blood, and then we faint.
Usually this type is harmless and doesn’t require any treatment, unless it happens frequently, in which case there are drugs which can help.

Here are some live examples:

2. Orthostatic:

In this type, your blood pressure drops when you get up from sitting or lying down.
When we stand up, blood pools to our legs due to gravity. Usually, special cells in the body sense this and cause our heart to pump faster and harder in order to get more blood up to the brain. When these cells don’t function properly, orthostatic hypotension occurs, causing you to faint.
There are a few things which can cause this:
a.  Dehydration
b. Some forms of drugs
c. Diabetes – Diabetes can damage nerve cells, like the ones responsible for sensing the low blood pressure here.
d. Other neurologic problems

Thirsty? You might faint. Photo by hrtmnstfr.

3. Cardiovascular:

You may also faint if you have problems with your heart. Such problems can include problems with your heart rate (which in medicine are called arrhythmias), and can also include mechanical problems with the heart, which cause it to not pump enough blood to your brain.

4. Neurologic:

There are some neurologic conditions which can make you faint:
a. Seizures – Technically, this isn’t syncope. Your brain does get enough blood, but it doesn’t function properly. (In the future we will cover epilepsia here, so stay tuned).
b. Stroke
c. Migraines

5. Miscellaneous:

There are other things which can cause you to faint, including:
a. Low sugar in your blood
b. Not getting enough oxygen (such as when you dive, or in a fire)
c. Anemia

Even with all this knowledge, in about 35% of cases, the reason behind the faint can’t be found.

Now it’s your turn. Have you ever fainted? Was the reason found? Let us know in the comments.

What next?

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