Shamai Grossman, an associate professor of emergency medicine at Harvard Medical School, who has conducted 20 studies on fainting. Fainting usually is caused by a temporary drop in blood pressure. During that brief drop, the brain does not get the blood flow that it needs—and you lose consciousness. One serious cause of this drop in blood pressure is bleeding, such as in the stomach or intestines, or from a rupture of the body's main artery, the aorta.
Several different heart problems also can temporarily lower blood pressure. One is heart block, in which the heart beats too slowly to pump enough blood.
An irregular rhythm of the heart's main pumping chambers, the ventricles, can cause the heart to pump blood less efficiently. Abnormalities of a heart valve, particularly a stiffening of the aortic valve, also can cause a temporary loss in pressure. All of these heart problems often produce symptoms such as palpitations a feeling like your heart is skipping a beat or racing , shortness of breath, or chest tightness.
If you have any of these symptoms, it is urgent that you get to the hospital. Another serious cause of a sudden loss of consciousness is a seizure, which is an abnormality of the brain, not related to blood pressure. Some seizures produce dramatic shaking movements and loss of consciousness for longer than most fainting spells. However, other seizures can be more subtle and hard to recognize as seizures. Sometimes fainting is caused by stimulation of the vagus nerve, which can briefly lower both heart rate and blood pressure.
The condition is called vasovagal syncope SIN-cope-ee. It can occur if you strain while having a bowel movement or, for men, while passing urine , have blood drawn, get an injection, hear bad news, or even laugh too hard.
These kinds of fainting episodes commonly affect young people but can occur in older adults. Just before a person faints from vasovagal syncope, he or she often feels nauseated or breaks out in a cold sweat. You may lose consciousness for just a moment if your blood pressure drops when you stand, a condition called orthostatic hypotension.
A visit to your doctor is the only way to find out if you have high blood pressure. Your doctor will take several blood pressure readings using a device called a sphygmomanometer and run a few routine tests.
Your doctor may also use a device called an ophthalmoscope to look at the blood vessels in your eyes. Doctors can see if these vessels have thickened, narrowed, or burst, which may be a sign of high blood pressure.
Your doctor will also use a stethoscope to listen to your heart and the sound of blood flowing through your arteries. In some cases, a chest x-ray and electrocardiogram may be needed. Blood pressure readings measure the two parts of blood pressure: systolic and diastolic pressures. Systolic pressure is the force of blood flow through an artery when the heart beats. Diastolic pressure is the force of blood flow within blood vessels when the heart rests between beats. A blood pressure reading measures both the systolic and diastolic forces, with the systolic pressure listed first.
The numbers show your pressure in units of millimeters of mercury mm Hg —how high the pressure inside your arteries would be able to raise a column of mercury. If you have been getting frequent crushing headaches or experiencing intense brain fog, you need to visit the doctor immediately. Tiny, delicate blood vessels transport blood to the eyes. Long-term high blood pressure can squeeze off blood flow and damage the blood vessels.
Fluid may build up under the retina, making you lose focus of objects. These blocks can cause distortion of vision and even result in complete loss of vision. If you are experiencing blurry vision or noticeable swelling in your eyes, make an appointment to see a doctor right away. Dizziness and feeling slightly off balance are early warning signs of a stroke caused by high blood pressure. These symptoms occur due to lack of oxygen supply to the brain.
Hypertension is a chronic condition that can be managed with lifestyle changes including a healthy diet and regular exercise. Similarly, slurred speech, facial droop or weakness in any limbs are signs of a serious problem. If possible, lie down and elevate the feet. This may prevent a loss of consciousness. Fresh air can also help, especially if you are feeling hot.
If it is not possible to lie down, put your head down as low as possible. If you do faint, remain lying down for ten minutes. Sit up slowly when you need to get up. Low blood pressure hypotension is a condition characterised by blood pressure that is lower than normal or usual for the person.
Hypotension can be caused by a variety of factors including heart disease and abnormal heart rhythms, some infections, dehydration and medications for high blood pressure or certain heart conditions. Frequent fainting spells or sensations of light-headedness need to be medically investigated to check for underlying causes. Blood vessels respond to gravity by constricting tightening. This increases or maintains blood pressure when we stand up from a sitting or lying position.
For this reason, some people, particularly the elderly or those on blood pressure medication, should stand up from sitting or lying in bed slowly. This helps prevent fainting after sudden changes in position.
Causes of orthostatic hypotension include:. This page has been produced in consultation with and approved by:. The type of pain felt in the abdomen can vary greatly.
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