Fainting is a temporary loss of consciousness caused by reduced blood flow to the brain, typically with a rapid onset and recovery within two to three minutes. In young people, most fainting episodes are benign, often triggered by prolonged standing, hot weather, strong emotions, or dehydration. However, in some cases, fainting can indicate an underlying cardiovascular disease.

Benign fainting episodes often have warning signs, such as feeling dizzy, nauseous, sweating, blurred vision, or ringing in the ears for several seconds to a few minutes before losing consciousness. This "warning" period allows individuals to react by sitting or lying down, which helps reduce the risk of falls and injuries.

In other cases, fainting occurs suddenly without warning signs, with the individual losing consciousness immediately while standing, walking, or performing normal activities. This type of onset often suggests a cardiovascular cause. As there is no time to recognize and prevent it, individuals experiencing this are at a higher risk of falls and injuries, necessitating early medical examination to determine the cause.

Fainting during activities like running, gym workouts, or playing sports, as in your case, is a concerning sign. During physical exertion, the body should increase heart rate and blood pressure to meet circulatory demands. However, if this mechanism is disrupted, blood flow to the brain suddenly decreases, leading to fainting.

Master of Medicine, Doctor Dat examines and advises a patient. Illustration: Tam Anh General Hospital

Fainting accompanied by palpitations or chest pain may indicate an electrical disturbance in the heart, reducing its pumping efficiency and causing a sudden drop in blood flow to the brain. Genetic factors play a significant role in some heart conditions. If there is a family history of sudden death at a young age, the risk of cardiac fainting is higher among other family members.

Recurrent fainting, occurring two or more times within a short period without clear triggers, could signal a heart conduction abnormality or an electrical heart rhythm disorder that requires thorough evaluation.

In your situation, to accurately determine the cause of your fainting episodes, you should seek an early medical examination so a doctor can order necessary tests. If fainting occurs frequently or is accompanied by suspicious symptoms such as palpitations, chest pain, or fainting during activity, a consultation should be arranged even sooner.

Methods to differentiate between benign and dangerous fainting include an electrocardiogram (ECG), a 24-72 hour Holter monitor, an echocardiogram, and a tilt table test.

If diagnosed with reflex syncope, individuals typically manage it through lifestyle changes and early recognition of triggers. Maintaining adequate hydration helps stabilize circulatory volume and prevent blood pressure drops. It is important to avoid standing for too long, especially in hot, stuffy environments. Regular eating also helps prevent relative hypoglycemia.

Individuals should recognize warning signs such as dizziness, nausea, and sweating to promptly sit or lie down. For those prone to fainting, additional measures like contracting leg muscles, crossing legs, or clenching hands can be applied when feeling lightheaded to temporarily maintain blood pressure.

If fainting is caused by a cardiovascular condition, a doctor will advise on appropriate treatment to prevent dangerous complications.

Master of Medicine, Doctor An Tuan Dat

Cardiology Department

Tam Anh Cau Giay General Clinic