Dr Aidin Rawshani

Low blood pressure (hypotension)


Overview of low blood pressure

Low blood pressure may seem desirable, and for some people, it does not cause any problems. However, for many people, abnormally low blood pressure (hypotension) can cause dizziness and fainting. In severe cases, low blood pressure can be life-threatening. Blood pressure lower than 90 millimeters of mercury (mm Hg) for the upper pressure (systolic) or 60 mm Hg for the lower truck (diastolic) is considered blood pressure.

Blood pressure is the force of blood that presses against the walls of your blood vessels (arteries) when the heart pumps blood. For most adults, healthy blood pressure is usually less than 120/80 mm Hg.

  • Blood pressure around 120/80 mmHg is normal
  • Blood pressure lower than 90/60 mmHg is defined as hypotension

Some people have low blood pressure all the time, and this is normal for them. Other people experience a sudden drop in blood pressure or have low blood pressure that may be linked to a health problem. Many systems of the body, including organs, hormones and nerves, regulate blood pressure.

Blood pressure is a measurement of the pressure in your arteries during the active and dormant phases of each heartbeat.

  • Systolic Pressure — The top digit of a blood pressure reading is the pressure your heart generates when you pump blood through your arteries to the rest of your body.
  • Diastolic pressure — The lower number of a blood pressure reading refers to the pressure in your arteries when your heart rests between heartbeats.

During the day, blood pressure varies depending on body position, respiratory rhythm, stress level, physical fitness, medications you take, what you eat and drink and time of day. Blood pressure is usually the lowest at night and rises sharply upon awakening.

What is low blood pressure?

What is considered low blood pressure for you can be normal for someone else. Most doctors believe that blood pressure is too low only if it causes symptoms.

Some experts define low blood pressure as readings lower than 90 mm Hg systolic or 60 mm Hg diastolic. If any of the numbers are below it, then your pressure is lower than normal.

A sudden fall in blood pressure can be dangerous. For example, a change of only 20 mm Hg, from 110 systolic to 90 mm Hg systolic, can cause dizziness and fainting when the brain does not receive sufficient blood supply. Severe reductions in blood pressure such as those caused by uncontrolled bleeding, severe infections or allergic reactions, can be life-threatening.

Causes of low blood pressure

The autonomic nervous system is that part of the nervous system of the body that is automatically controlled by various parts of the brain. The autonomic nervous system is essential for the regulation of the blood pressure of the body. The body controls blood pressure without us thinking about it. In Parkinson’s disease, the autonomic nervous system is affected, which can cause low blood pressure. Individuals with diabetes do not usually have low blood sugar but may still experience symptoms such as low blood pressure. One of the reasons for this is that high blood sugar levels affect the blood vessels in the body, hyperglycemia leads to atherosclerosis. Elderly people with atherosclerosis can often develop symptoms, as with low blood pressure, a sudden change in body position is often observed.

Medical causes of low blood pressure

  • Pregnancy — As the circulatory system expands rapidly during pregnancy, blood pressure is likely to drop. This is normal, and blood pressure usually returns to your levels before pregnancy after giving birth.
  • Heart problems — Some heart diseases that can lead to low blood pressure, such as low heart rate (bradycardia), heart valve problems, heart attack and heart failure.
  • Endocrine (hormonal) problems — Thyroid conditions, such as parathyroid disease, adrenal insufficiency (Addison’s disease), low blood sugar (hypoglycemia) and in some cases diabetes can trigger low blood pressure.
  • Lack of fluid — When your body loses more water than your body takes in, it can cause weakness, dizziness and fatigue. Fever, vomiting, severe diarrhea, over-use of diuretics and strenuous workouts can lead to fluid deficiency.
  • Blood loss — Losing a lot of blood, for example from a major injury or internal bleeding, reduces the amount of blood in the body, leading to a severe Blood pressure lower.
  • Serious infection (septicemia) — When an infection in the body enters the bloodstream, it can lead to a life-threatening drop in blood pressure called septic shock.
  • Severe allergic reaction (anaphylaxis) — Common triggers of these serious and potentially life-threatening reaction foods, some medications, insect venom and latex. Anaphylaxis can cause breathing problems, hives, itching, swelling of the throat and a dangerous drop in blood pressure.
  • Lack of nutrients in your diet — Lack of vitamins B-12 and folate can slow the body from producing enough red blood cells (anemia), causing low blood pressure.

Drugs that can cause low blood pressure

  • Diuretics (diuretic) drugs such as Furosemide (Lasix) and Hydrochlorothiazide (Maxzide, Microzide, others)
  • Alpha-blockers, such as Prazosin (Minipress)
  • Beta-blockers, such as atenolol (Tenormin) and Propranolol (Anaprilin, Innopran)
  • Drugs for Parkinson’s disease, such as pramipexole (Mirapex)
  • Some types of antidepressants (tricyclic antidepressants), including doxepin (Silenor) and imipramine (Tofranil)
  • Drugs for erectile dysfunction, including sildenafil (Revatio, Viagra) or tadalafil (Adcirca, Cialis), especially when taken with Cardiac Medicine Nitroglycerin

Elderly individuals with low blood pressure or who suddenly develop a fall in blood pressure have a higher risk of developing symptoms from low blood pressure, such as cases, fainting or dizziness. Symptoms usually occur when standing up or after a meal. Older adults are also more likely to develop low blood pressure as a result of drugs against hypertension. Several antihypertensive drugs can be powerful for the individual and cause low blood pressure.

For many people, low blood pressure goes unnoticed. Below are listed symptoms in low blood pressure.

Symptoms in low blood pressure

  • Fatigue
  • Weakness
  • Confusion
  • Blurred vision
  • Neck or back pain
  • Nausea

Sitting down can alleviate these symptoms. If blood pressure drops too low, the vital organs of the body do not receive enough flow of blood (oxygen and nutrients). When this happens, low blood pressure can lead to shock, which requires immediate medical attention. Signs of shock include cold and sweaty skin, rapid breathing, a blue skin tone or a weak and rapid pulse.

Diagnosing low blood pressure

Your doctor will prescribe a blood pressure test to diagnose low blood pressure, which involves measuring blood pressure in the arm with a blood pressure cuff. Other tests may include blood tests or urine samples. In some cases, one can prescribe to physiological examinations in which to measure blood pressure after a sudden change in body position. These examinations are conducted in specialists in clinical physiology or biomedical analysts.

Treatment of low blood pressure


Depending on the signs and symptoms, treatment may include drinking more fluids, taking medications to raise blood pressure or adjusting drugs that cause low blood pressure.

Lifestyle changes

Recommended lifestyle changes include changing what and how you eat and how you sit and stand up. Your doctor may also recommend compression stockings if you have to stand for long periods.

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