Is Fainting Dangerous? Know Its Causes, Symptoms, And Treatment

Most of us have experienced fainting at least once in our lives. It is the sudden loss of consciousness, usually caused by a sudden drop in blood flow to the brain. What other health issues can cause fainting? What are the symptoms, treatment, and diagnosis for fainting? Today, we will answer all these for you. 

To get a better understanding of this, we reached out to Dr Pooja Pillai, Consultant - Internal Medicine, Aster CMI Hospital, Bangalore, and Dr Piyush Harchand, Associate Consultant, Internal Medicine, Fortis Hospital, Ludhiana.

What Causes Fainting?

Let us dive right in: what exactly is the reason behind fainting? “Fainting happens when the brain does not get enough blood flow for a short time,” says Dr Pillai. Shedding more light on this, Dr Harchand explains, “Our neurons need a constant oxygen supply to produce Adenosine Triphosphate (ATP), also known as the energy carriers in cells. A shortage or even a minor disruption in blood flow (and therefore oxygen) causes a reduction in the ATPs, not allowing enough energy to flow to different parts of the brain. This causes a minor shutdown or fainting. The supply of oxygen-rich blood to the brain must be maintained. In medical terms, fainting is called syncope.”

Dr Harchand adds that the disruption of oxygen flow to the brain can be due to several underlying factors, including:

• Sudden drop in blood pressure or heart rate.
• Dehydration or low blood sugar.
• Heat exposure.
• Emotional triggers like fear, pain, and seeing blood.
• Structural heart diseases, arrhythmias (irregular heartbeats), or valve problems.
• Damage to the aorta, the artery that carries blood from the heart to the rest of the body.
• Pregnancy.

According to the National Institutes of Health (NIH), fainting (medically known as syncope) is when a person passes out for a short period of time, but then wakes up relatively quickly. This happens when the brain doesn’t receive enough blood for a short time. It generally lasts for a few minutes before an individual slowly returns to normal. It further notes that it is not a disease, but a symptom with multiple possible causes. Most often, fainting is linked to temporary drops in blood pressure and is not serious. However, heart rhythm problems or other medical conditions can cause fainting in certain rare cases. 

As per a 2023 study, published in the ‘Nature’ journal, researchers have attempted to explain the biological reason behind fainting. The scientists noted that physical symptoms of fainting are induced when a specific cluster of sensory nerves, located in the lower heart muscle, is triggered. The study added that during fainting, a particular brain region stays alert, which helps the body wake up quickly, while most brain activities are shut down for a short period.

What Are The Types Of Fainting? 

Fainting is usually categorised into three different types. Dr Harchand lists them for your better understanding:

Reflex or Vasovagal Syncope

This is the most common type of syncope. It involves the vagus nerve (responsible for maintaining involuntary functions such as digestion and heart rate) and often happens when the body overreacts to triggers like the sight of blood, heat exposure, or intense pain. This overreaction causes a sudden drop in the heart rate and blood pressure. This is usually harmless.

Orthostatic Hypotension Syncope

This occurs from a change in body position. Standing up too quickly from a lying or seated position causes a temporary drop in blood pressure.

Cardiac Syncope

It is either caused by an underlying heart condition, arrhythmias (abnormal heart rhythms), structural heart problems, or major vascular or cardiac problems that can reduce blood flow to the brain.

According to a 2024 study, published in the ‘Journal of Clinical Medicine’, researchers attempted to understand how to differentiate between a normal fainting (caused by physical reflexes such as stress) and those led by serious hidden heart conditions. The study mentioned taking note of factors like how fast you wake up, or whether you feel confused right after or not, to understand the severity of fainting. The findings further noted that if you faint while lying down, or during a workout, or experience chest pain during that time, then it may be a warning sign of something serious. 

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What Are The Symptoms And Diagnosis For Fainting? 

According to the Cleveland Clinic, some of the common symptoms of fainting include:

• Black out.
• Falling.
• Dizziness.
• Drowsiness.
• Feeling unsteady or weak (when standing).
• Seeing spots or experiencing tunnel vision.
• Headaches.
• Sweating or feeling nauseous.

Let us see what our experts have to say about this. “Symptoms of fainting usually appear before a person loses consciousness. These include feeling dizzy, lightheaded, weak, or nauseous, along with sweating, blurred vision, or ringing in the ears. Some people may notice pale skin or a slow pulse. The person may briefly lose consciousness and recover quickly,” shares Dr Pillai.

Speaking about its diagnosis, Dr Harchand lists the following methods: 

• ECG (Electrocardiogram): This records the electrical activity of the heart to check for arrhythmias.
• Tilt Table Test: You lie on a table that shifts from horizontal to vertical while clinicians monitor your blood pressure and heart rate.
• Blood Tests: These check for anaemia or metabolic imbalances.
• Holter Monitor: A portable device records the heart rhythm over 24-48 hours.

Can Fainting Suggest Serious Conditions?

According to the American Heart Association, certain types of fainting may indicate a serious disorder. These include:

• Fainting that occurs during exercise or exertion.
• Fainting that is related to palpitations or irregularities of the heart.
• Fainting is linked to a family history of recurrent syncope, heart disease at a young age, or sudden death.

Prevention Tips And Treatment For Fainting

Dr Pillai shares some tips to prevent fainting: “People should stay well hydrated, avoid skipping meals, and stand up slowly from sitting or lying positions. Avoiding triggers like standing for long, heat, stress, or crowded places can also help. If warning signs like dizziness or sweating appear, sitting or lying down immediately can prevent a fall.”

What about the treatment options for fainting? Explaining this, Dr Harchand jots the following:

• Treatment for an acute fainting episode involves checking the person's airway and breathing. Loosen tight clothing, especially around the neck.
• Raise the person's feet about 12 inches above the level of the heart.
• Pacemakers may be used in selected patients with specific, diagnosed slow heart rhythms that cause fainting. They help maintain heart rate in those cases and are not a general treatment for all fainting.
• If fainting is caused by underlying neurological or cardiac issues, checking with the respective specialist is a must.

A 2023 study, published in the ‘EP Europace’ journal, analysed 25 years of research and summarised over 400 studies. The findings stated that fainting is triggered generally by a drop in Blood Pressure (BP), an alarmingly slowed heart rate, or both. It further noted that modern diagnostic approaches can now clearly distinguish between fainting caused by heart conditions and that caused by the nervous system. These discoveries have paved the way for new medications, lifestyle therapies, and medical procedures to treat fainting more effectively. 

When To See A Doctor?

Dr Harchand shares that an individual should visit a doctor due to fainting if:

• If the patient or the patient’s family has a known medical history, heart disease, or diabetes.
• The syncope episodes are frequent. Fainting more than once in a short period may be due to underlying health factors.
• You experience chest pain or shortness of breath before or after the episode.
• If the fainting occurred without prodromal symptoms like nausea or dizziness.

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Conclusion

When the brain does not get enough blood flow for a short duration, fainting occurs. Visit a doctor if fainting happens often or without a clear reason. Seek medical help if it occurs during exercise, or is followed by chest pain, shortness of breath, or a fast or irregular heartbeat. Early medical evaluation helps find the cause and prevent complications or future episodes.