What to know about low blood pressure

What to know about low blood pressure

Low blood pressure can lead to dizziness and faintness, or to hypotension. It is less likely to be problematic than high blood pressure, but often it may suggest an underlying health concern.

Two numbers are used in blood pressure readings. The top number indicates the systolic pressure, which is the pressure when the heart contracts, and the diastolic pressure, which is the pressure between heartbeats, is given by the bottom number. A low blood pressure adult would have a mercury reading of less than 90/60 millimetres (mm Hg).

Doctors do not generally consider low blood pressure a concern, according to the American Heart Association (AHA), unless it produces obvious signs and symptoms.

The symptom of an allergic reaction or internal bleeding may be extremely low blood pressure. When oxygen and nutrients are unable to enter the brain, heart, and other vital organs, it can be life threatening.

However, having persistently low blood pressure is usually better than having high blood pressure because it poses a lower risk of multiple health issues.

What is blood pressure?

The heart is a muscle that continually pumps blood, providing all areas of the body, including the vital organs, with oxygen and nutrients.

Blood pressure is produced by this pumping action and blood pressure against the blood vessels.

During the day, blood pressure will vary. When a person is sleeping or resting, it is lower. During physical exercise and in periods of stress and anxiety, it may be even greater.


There are no signs in certain persons with low blood pressure. The wellbeing of those who are very fit with low blood pressure may be excellent.

However a chronic disorder, such as a hormone imbalance or an acute condition, such as anaphylaxis, may also be demonstrated by hypotension.

Common symptoms include:

  • lightheadedness
  • dizziness
  • fainting

Symptoms that can result from an underlying cause include:

  • chest pain
  • cold, pale, dry, or clammy skin
  • fever
  • a headache and a stiff neck
  • vision changes
  • diarrhea and vomiting
  • allergic reactions, such as swelling
  • difficulty breathing
  • fatigue and weakness
  • thirst and dehydration
  • changes in heart rhythm

What is a normal blood pressure?


Two main mechanisms rely on blood pressure: the working of the heart and the resistance of the blood vessels.

These processes determine the extent to which blood pressure will be high or low in accordance with the effects of neurological and hormonal causes.

Possible hypotension causes include:

Orthostatic or postural hypotension

Standing up from a sitting or lying position can lead, along with dizziness or faintness, to a drop in blood pressure.

Heart disease

It does not pump enough blood to maintain blood pressure within the normal range if the heart does not function properly.


During gestation, the circulatory system expands, and this also results in low blood pressure. Hypotension is seldom a cause for alarm during pregnancy.

After eating

After feeding, blood pressure often drops as the intestines require an increased blood supply for digestion. In older people, particularly those with high blood pressure, diabetes, or Parkinson’s disease, hypotension after eating is more common.


When using the bathroom, swallowing, or coughing, blood pressure will decrease. The vagus nerve, which lowers blood pressure, is all activated by these actions.

Hormonal problems

Hormones that help manage different body functions, including heart rate and blood pressure, are made and stored by the thyroid gland. The adrenal glands regulate the reaction to stress. Problems can lead to hypotension with either form of gland.

Neurally mediated hypotension

Low blood pressure may result from defective signals between the heart and brain.


Blood pressure can be lowered by beta-blockers, calcium channel blockers, and diuretics. Healthcare professionals can lower blood pressure purposely during surgery to decrease the risk of blood loss.

Dietary deficiencies

Low vitamin B12 and folic acid levels can contribute to anemia, which can lead to low blood pressure in turn.

Eating disorders

A low intake of calories can affect the structure of the heart in people with anorexia nervosa, lowering blood pressure. Electrolyte deficiency can be caused by bulimia nervosa, raising the risk of irregular heartbeats and heart failure.

Hypotension and shock

Extreme hypotension can lead to shock caused by hypotension. Depending on the source, there are numerous methods of expressing shock.

  • Hypovolemic shock: The total volume of blood falls, and the heart can no longer pump effectively. Possible causes include severe internal or external bleeding or severe dehydration. Dehydration can result from a high urine output — due, for example, to a hormone imbalance or the overuse of diuretics — or a loss of fluid due to diarrhea and vomiting.
  • Cardiogenic shock: The heart is unable to function effectively due to cardiovascular problems. A person may have a low heart rate and cool, dry extremities and skin.
  • Distributive shock: The vascular system loses resistance, and the heart is unable to pump fast enough to compensate. Causes include an allergic reaction (anaphylactic shock) and septic shock, which is a possible complication of an infection.
  • Obstructive shock: An obstruction in the cardiovascular system stops the heart from pumping effectively or prevents the blood from flowing. Causes include pulmonary embolism. A person’s jugular veins may be distended, and they may have quiet heart sounds.

Hypotensive shock is the name of any combination of these. Whatever the cause, a shocked person will require immediate medical treatment.

When to see a doctor

If their blood pressure falls suddenly, is very low, or is significantly lower than normal, a person should seek medical advice.

If they have other symptoms, such as frequent urination, fever, or fatigue, as these may suggest an underlying illness, they should also seek advice.

With very low blood pressure, the brain and other vital organs can suffer from insufficient blood and oxygen. It may be appropriate to provide emergency medical treatment.

Whoever is with them should take immediate action if a person shows signs of anaphylaxis. A bystander may help them administer it if the person carries an autoinjector. They should also call 911.


There are different kinds of blood pressure monitors available. Usually, monitors for home use are optical devices. To verify if the problem is ongoing, it is best to take many readings.

Devices used by healthcare professionals in a healthcare setting can enable them to listen while reading a mercury gauge for changes in pressure with a stethoscope.

A doctor may also ask the individual about his or her medical history and other symptoms. To rule out an underlying issue, they can carry out other tests.


There’s no need for medication for most people with low blood pressure. However if hypotension starts unexpectedly or results from an underlying disorder, adequate care will be given by a doctor. The choices for therapy will depend on the cause.

Treatment may involve a doctor:

  • prescribing medication to help resolve low blood pressure
  • changing a person’s medication or dosage, if they suspect that either of these is responsible
  • suggesting dietary changes, such as increasing the intake of salt or fluid

Before making any drastic changes to their diet or drug use, people should always talk to a physician.


A range of lifestyle measures can help prevent low blood pressure.

These include:

  • taking time to stand up from a sitting or lying position
  • using blocks to raise the head of the bed by 6 inches
  • eating small meals frequently and resting after eating
  • increasing fluid intake
  • avoiding long periods of sitting or standing still
  • avoiding suddenly changing posture or position
  • moderating alcohol intake
  • refraining from drinking caffeinated beverages late in the day
  • wearing support stockings


Usually, low blood pressure is not a cause for concern. However if their symptoms are serious or lead to other issues, such as frequent falls, a person may need medical attention.

Emergency medical attention could be appropriate if blood pressure drops unexpectedly. Examples of when this might happen include:

  • a trauma leading to external or possible internal bleeding
  • exposure to an allergen, such as an insect sting
  • severe dehydration
  • an infection that may have spread to another part of the body

In these cases, because of a lack of oxygen, the person may need treatment for shock and to avoid damage to the brain and other organs.