What is fainting?
Fainting is a brief, sudden loss of consciousness. You become
unresponsive, lose muscle tone, and may fall. Usually, there is
complete recovery in a matter of seconds to a few minutes.
Fainting is fairly common. The medical term for fainting is
syncope.
How does it occur?
There are many different reasons for fainting. Usually fainting is
not caused by a serious or life-threatening medical problem.
However, if you are known to have heart disease, or you faint
during even mild exercise, the cause may be serious and you may
need prompt medical attention.
One of the most common and least worrisome reasons for fainting is
anxiety or other emotional upset.
You may faint if you have not had enough liquids, especially if
you stand up too quickly. This happens more often after illness or
working in the hot sun.
As people age, the ability of the nervous system to control blood
pressure becomes less sensitive. Rising from a lying to a standing
position, or standing for a long time, may cause low blood
pressure. This condition, called orthostatic hypotension, can
cause fainting. This happens because not enough blood is pumped
from the heart to the brain. It can be worse right after eating.
Low blood sugar from diabetic treatment or other causes can also
cause fainting.
Some medicines, such as diuretics (water pills) and blood
pressure-lowering medicines may cause fainting.
A common type of fainting is called vasovagal syncope. It can
happen when you take a deep breath and push down but don't allow
yourself to breathe out. You may do this, for example, when you
urinate or have a bowel movement or when you cough hard or long.
Vasovagal syncope can also occur if you stand in one place for too
long. Before you faint, you may feel giddy, lightheaded, or
flushed. The fainting is caused by nerve impulses that slow the
heart rate. As a result, the heart temporarily pumps less blood to
the brain. This is the most common cause of fainting in healthy
young adults.
Temporary pressure on a sensitive spot in the neck causes fainting
in some people.
Sometimes heart problems cause fainting.
- Irregular heart rhythms are the most common heart-related
cause of fainting. The heart may beat so rapidly that too
little blood gets to the brain. Or a very slow heart rate
caused by heart block or pacemaker failure may cause fainting.
- Some heart attacks immediately damage the pumping muscle and
cause fainting.
- Abnormal heart valves can cause drops in blood pressure that
lead to fainting.
Faints also occur because not enough oxygen is getting to the
brain.
What are the symptoms?
You may faint suddenly without any symptoms. Or at first you may
feel nauseous or sweaty. If your fainting is caused by a heart
problem, you may have a fast or irregular pulse. Sometimes people
say they felt like their heart was jumping around in their chest.
You may feel short of breath or pressure in your chest. If you
have a heart valve problem, you may have some chest pain,
especially with exertion, before you faint.
How is it diagnosed?
Your healthcare provider will ask about your medical history,
particularly about the times you have fainted. How you felt before
and after you fainted are important facts that can help in making
the diagnosis. Your provider will ask about the medicines you take
and will examine you.
Depending on your age and health history, your healthcare provider
may want to do some tests.
- If your healthcare provider thinks a heart problem may be the
cause of the fainting, you may have an electrocardiogram (ECG
or EKG). The ECG records the electrical impulses from your
heart. If the first ECG is normal, your provider may want to
monitor your heart for a longer period of time. A special type
of ECG called a Holter monitor can be worn for 1 to 3 days to
make a recording of your heart rhythm, or another type of
monitor called an event recorder can be used for several weeks
at a time.
- You may have an ultrasound test of the heart called an
echocardiogram to see if there are any problems with the heart
muscle or the heart valves.
- You may have a stress test which will give information about
the heart rhythm and the blood flow to the heart.
- You may have a chest X-ray.
- A tilt table test helps to diagnose syncope. In this test,
your blood pressure is measured while the table on which you
are lying is progressively tilted toward the head-up position.
- Sometimes your healthcare provider may order a test of the
electrical system of the heart called an electrophysiology
study.
Even with all these tests, the exact cause for fainting may not be
discovered.
How is it treated?
The treatment of fainting is based on the cause.
- If vasovagal syncope is the problem, pay attention to what
happens right before you faint. When you have these symptoms,
take precautions to avoid fainting, or to stop from getting
hurt if you do faint. For example, try to lie down before you
faint.
- A careful review by your healthcare provider of the medicines
and dosages you take can eliminate drugs as a cause for
fainting.
- Orthostatic hypotension, or a marked fall in blood pressure
when you are standing up, can be helped by wearing support
hose. Getting up slowly from lying or sitting also helps.
- Heart-related problems can often be repaired. Heart valves
causing blockage can be replaced. Pacemakers can be inserted
to correct very slow heart rates.
How do I prevent fainting?
- Follow your healthcare provider's instructions carefully.
- Drink plenty of liquids, especially in hot weather.
- Eat a healthy diet and eat at regular times throughout the
day.
- Let your healthcare provider know if your symptoms are getting
worse or happening more often, and if you have had a recent
change in medicines.
This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
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