Fainting: what it is, causes and signs of sudden loss of consciousness

First the world loses its colors: fog before the eyes, ringing in the ears, legs turn to jelly. Then — a brief blackout, and the person is already on the floor, pale and sweaty, and half a minute later comes to again. Fainting is such a brief loss of consciousness caused by a temporary decrease in cerebral blood flow.

Fainting: what it is

Fainting, or syncope, is a sudden brief loss of consciousness of non-epileptic nature. It occurs due to a diffuse decrease in cerebral metabolism caused mainly by a brief reduction in cerebral blood flow. Usually this happens when blood pressure drops sharply and the brain does not receive enough blood for a few seconds. The duration of fainting is from a few seconds to one minute. In deep fainting, consciousness may be absent for up to several minutes, in extremely rare cases — up to a maximum of 30 minutes. Fainting and an epileptic seizure look similar from the outside — the person falls and loses consciousness — but these are two completely different conditions that require different approaches.

Signs of fainting and presyncope

Loss of consciousness is often preceded by a presyncopal state, or presyncope: dizziness, cold sweat, darkening of vision. The person feels nausea, weakness, sometimes yawning, legs give way and a feeling of impending loss of consciousness appears. During the fainting itself, the skin is ashen-gray, blood pressure drops sharply, the pulse may be extremely slow or fast but thready, barely palpable. Muscles are relaxed. At the height of fainting, convulsive twitching and involuntary urination are possible.

What causes people to faint

There are many causes, and they differ in nature. Among them — a sudden rise, when a person stands up too quickly, which may be a sign of low blood pressure; lack of food or drink; overheating; severe emotional shock; heart problems; taking medications or excess alcohol. There are conditions with impaired nervous regulation of blood vessels: fainting when swallowing, when rising quickly from a horizontal position. Fainting also occurs with low oxygen content in the blood — in anemia, in thin air or in stuffy rooms.

Hunger fainting: connection with nutrition and blood sugar

Among the causes of fainting are lack of food or drink, as well as a drop in blood sugar levels. Metabolic disorders, including hypoglycemia and anemia, are classified as conditions in which consciousness is lost without a sudden drop in cardiac output. So "hunger" fainting is not a myth: the body reacts to a lack of fuel.

Causes of fainting in women

There is no separate "female" cause of fainting, but there is a situation more often noted in girls: fainting during hair care — when combing or drying with a hairdryer. In adolescent girls, fainting is generally more common: the average age of fainting is 10–12 years, and for ages under 5 it is a rare phenomenon.

When fainting indicates a disease and a doctor is needed

Fainting itself is usually not a sign of something serious, but it can be a symptom of an underlying disease, so after it occurs a doctor is consulted to determine the cause. The doctor assesses the circumstances of the loss of consciousness, checks breathing and heart function, and if necessary refers for additional examinations. Fainting during physical activity and fainting in a lying position are distinguished separately: this is a reason for closer attention.

• Fainting occurred during physical exertion
• Fainting occurred in a lying position
• Loss of consciousness was accompanied by pain or palpitations in the chest
• The person has not fully recovered, has difficulty with speech or movement
• There were seizures or the person was seriously injured in the fall

Fainting itself is not a reason to call an ambulance; 103/112 — if the person is not breathing, does not come to for longer than a minute, has not fully recovered, or has impaired speech and movement, chest pain or a feeling of palpitations in the heart, was seriously injured before or after the fall, has seizures, and also if fainting occurred during physical exertion or in a lying position.

This article is for reference and does not replace a conversation with a doctor: it is better to find out the cause of fainting together with a specialist rather than guess.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer