Low Blood Pressure (Hypotension): Causes, Symptoms, Types, Diagnosis, and Treatment

Article Summary

Low blood pressure, also called hypotension, means blood pressure is lower than usual or low enough to cause symptoms. A reading below 90/60 mm Hg is often used as a general reference, but one number alone does not diagnose a problem. Some people naturally have low blood pressure without symptoms. Others develop dizziness, fainting, weakness, blurred vision, or falls, especially when standing or after meals. Causes include dehydration, blood loss, medicines, heart problems, hormone disorders, and nervous system conditions. Treatment focuses on the underlying cause, reducing symptoms, preventing falls, and restoring adequate blood flow when hypotension becomes severe.

Cite as: Low Blood Pressure (Hypotension): Causes, Symptoms, Types, Diagnosis, and Treatment. Brisbane (AU): Exon Publications; 2024 Apr 25 [updated 2026 Aug 21].

Introduction

Low blood pressure, or hypotension, is not always a disease. Some healthy people naturally have lower blood pressure and feel well. In others, blood pressure falls enough to reduce blood flow to the brain or other organs, causing dizziness, fainting, weakness, or more serious problems. The importance of a low reading therefore depends on the person's usual blood pressure, symptoms, how quickly the pressure fell, and the underlying cause (1, 2).

What Is Low Blood Pressure?

Blood pressure is the force of blood pushing against the walls of the arteries. It is recorded using two numbers. The systolic pressure, the upper number, measures pressure when the heart contracts. The diastolic pressure, the lower number, measures pressure when the heart relaxes between beats.

A blood pressure below 90/60 mm Hg is commonly described as low, but this is only a general reference point. Some people regularly have readings around or below this level without symptoms or harm. There is therefore no single blood pressure number that defines clinically important hypotension for everyone.

Low blood pressure becomes more concerning when it causes symptoms, develops suddenly, or prevents organs from receiving enough blood. The pattern of the blood pressure change can also be more important than the resting number itself (1, 2).

What Are the Main Types of Low Blood Pressure?

Low blood pressure can occur in several different patterns.

Persistent or constitutional low blood pressure refers to blood pressure that is naturally low over time. If the person feels well and there is no underlying disease, treatment may not be needed.

Orthostatic hypotension, also called postural hypotension, occurs when blood pressure falls after standing. It is generally defined as a fall in systolic pressure of at least 20 mm Hg or diastolic pressure of at least 10 mm Hg within about three minutes of standing (1, 2).

Postprandial hypotension is a drop in blood pressure after eating. Blood normally shifts toward the digestive system after a meal, and the body compensates by adjusting heart rate and blood vessels. This response may be inadequate in some people, particularly older adults and people with disorders of the autonomic nervous system (3).

Neurogenic orthostatic hypotension occurs when the autonomic nervous system cannot properly adjust blood vessel tone and heart function during standing. It can occur with conditions such as Parkinson disease, multiple system atrophy, pure autonomic failure, and some forms of neuropathy (2, 4).

Acute severe hypotension develops suddenly because of problems such as major blood loss, severe infection, serious heart disease, or a severe allergic reaction. When blood flow to vital organs becomes inadequate, this may progress to shock and requires urgent treatment.

What Causes Low Blood Pressure?

Low blood pressure has many possible causes, and more than one may be present at the same time.

Dehydration reduces the amount of fluid circulating in the bloodstream. It can result from vomiting, diarrhea, fever, heavy sweating, poor fluid intake, or excessive fluid loss through the kidneys.

Blood loss from an injury, surgery, or internal bleeding can cause a rapid fall in blood pressure.

Medicines are a common cause, particularly in older adults. Blood pressure medicines, diuretics, nitrates, alpha-blockers, some antidepressants, medicines for Parkinson disease, and several other drugs can contribute to hypotension or orthostatic symptoms (2, 4).

Heart problems can reduce the amount of blood pumped around the body. Examples include severe heart failure, heart attack, abnormal heart rhythms, and some valve disorders.

Hormone and metabolic disorders may also lower blood pressure. Adrenal insufficiency is one example. Low blood sugar and some thyroid disorders can contribute in certain situations.

Nervous system disorders can interfere with the body's automatic control of blood pressure. Diabetes can damage autonomic nerves, while some neurodegenerative diseases directly affect the nervous system pathways that control circulation (2, 4).

Prolonged bed rest, frailty, anemia, severe infection, pregnancy, and poor nutrition can also contribute in some people.

What Are the Symptoms of Low Blood Pressure?

Low blood pressure may cause no symptoms at all. When symptoms occur, they often reflect reduced blood flow to the brain.

Common symptoms include lightheadedness, dizziness, blurred or dimmed vision, weakness, fatigue, difficulty concentrating, nausea, and fainting. Symptoms may be most noticeable after standing, walking, exercising, taking a hot shower, or eating a meal (2, 4).

Orthostatic hypotension can also cause unexplained falls, particularly in older adults. Some people experience aching across the neck and shoulders while standing because of reduced blood flow to these muscles.

Not everyone with orthostatic hypotension feels obviously dizzy. Some people mainly notice tiredness, slowed thinking, unsteadiness, or reduced ability to remain standing for long periods (2).

When Is Low Blood Pressure an Emergency?

A low reading by itself is not necessarily an emergency. A person who normally has a blood pressure of 90/60 mm Hg and feels completely well may not have a medical problem.

Sudden low blood pressure is more serious when it occurs together with signs that vital organs are not receiving enough blood. Warning signs can include confusion, severe weakness, fainting, cold or clammy skin, rapid breathing, chest pain, severe shortness of breath, very little urine, or loss of consciousness.

Major bleeding, severe infection, heart problems, and severe allergic reactions can cause circulatory shock. In these situations, treatment is aimed at rapidly restoring circulation and correcting the underlying cause. Prolonged severe hypotension in critically ill people is associated with a greater risk of organ injury and poor outcomes (5).

How Is Low Blood Pressure Diagnosed?

Diagnosis begins with accurate blood pressure measurement and a careful description of the symptoms. One isolated low reading is usually not enough to explain recurrent dizziness or fainting.

The clinician may ask when symptoms occur, how long they last, whether they improve after sitting or lying down, what medicines are being taken, and whether there has been vomiting, diarrhea, bleeding, illness, weight loss, or another recent change.

For suspected orthostatic hypotension, blood pressure is measured after resting and again after standing. Current guidance generally uses a fall of at least 20 mm Hg systolic or 10 mm Hg diastolic within three minutes as the diagnostic threshold (1, 2).

Heart rate is also useful. The way the heart rate changes when blood pressure falls can provide clues about whether the problem is caused by dehydration, medicines, or impaired autonomic nervous system function (2).

Further tests depend on the likely cause. They may include blood tests for anemia, kidney function, electrolytes, glucose, or hormone disorders; an electrocardiogram to assess heart rhythm; and other heart tests when necessary.

When symptoms strongly suggest orthostatic hypotension but routine measurements are inconclusive, prolonged standing tests or a tilt-table test may be used. Blood pressure measurements before and after meals can help identify postprandial hypotension.

What Is Postprandial Hypotension?

Postprandial hypotension is a fall in blood pressure after eating, usually within the first two hours after a meal. It is particularly common in older adults and people with impaired autonomic nervous system function (3).

After a meal, more blood flows to the stomach and intestines. The heart and blood vessels normally compensate to maintain blood pressure. If this response is inadequate, blood pressure may fall enough to cause dizziness, weakness, fainting, or falls.

Large meals and meals high in rapidly absorbed carbohydrates may produce a greater drop in some people. Management may include smaller, more frequent meals, avoiding sudden activity immediately after eating, and adjusting the timing of medicines when appropriate.

A 2024 systematic review found postprandial hypotension to be common among older adults, although studies used different diagnostic methods and definitions (3).

How Is Low Blood Pressure Treated?

Treatment depends on why the blood pressure is low and whether it is causing symptoms. The goal is usually to improve symptoms and prevent falls or fainting rather than to raise the blood pressure to a specific number (4, 6).

If dehydration is the cause, replacing fluids may correct the problem. Blood loss, infection, heart disease, endocrine disorders, and other medical causes require treatment directed at the underlying condition.

A medication review is important because several medicines can lower blood pressure or worsen orthostatic symptoms. A medicine should not be stopped solely because it can cause low blood pressure; the balance between its benefits and side effects needs to be considered (4).

For chronic orthostatic hypotension, non-drug measures are usually tried first. These can include standing up slowly, avoiding prolonged standing, maintaining adequate fluid intake, avoiding excessive alcohol, and using physical counter-pressure movements such as crossing the legs or tightening leg muscles when symptoms begin (2, 4).

Compression garments or an abdominal binder can reduce pooling of blood in the lower body. In selected people, increasing dietary salt may help, but this is not appropriate for everyone, especially people with heart failure, kidney disease, or certain forms of hypertension (4).

What Medicines Can Be Used for Orthostatic Hypotension?

Medicines are considered when symptoms remain troublesome despite treating reversible causes and using non-drug measures.

Midodrine narrows blood vessels and can raise standing blood pressure. It can also raise blood pressure while lying down, so dosing needs to be timed carefully (4, 6).

Droxidopa increases norepinephrine activity and is used for some forms of neurogenic orthostatic hypotension. Its availability varies between countries (4).

Fludrocortisone increases sodium and fluid retention and has been used for many years, but it can cause swelling, low potassium, high blood pressure while lying down, and problems in people with heart or kidney disease. Current reviews therefore emphasize careful patient selection and monitoring rather than routine use for everyone (4, 6).

Other medicines may sometimes be used by specialists for difficult cases.

An important complication is supine hypertension, where a person has low blood pressure while standing but high blood pressure while lying down. Treatment must then balance relief of standing symptoms against the risk of making the lying-down blood pressure too high (1, 4).

How Can Symptoms of Low Blood Pressure Be Reduced?

Many episodes can be reduced by identifying the situations that trigger them.

People with orthostatic symptoms may benefit from changing position slowly, particularly when getting out of bed. Sitting on the edge of the bed briefly before standing can help.

Adequate hydration is useful when fluid restriction is not required for another medical condition. Excess alcohol can worsen hypotension and should be avoided or limited.

Long periods of standing, very hot environments, and hot showers can worsen symptoms because heat causes blood vessels to widen.

Regular appropriate physical activity can help maintain cardiovascular fitness and reduce deconditioning. People who have been inactive for long periods may need to increase activity gradually.

For postprandial hypotension, smaller meals may reduce the size of the blood pressure drop. The best strategy depends on the person's underlying condition, medicines, and other health problems (3, 4).

What Is the Outlook for People With Low Blood Pressure?

The outlook depends on the cause. Naturally low blood pressure without symptoms often requires no treatment and may remain harmless.

Hypotension caused by dehydration, medication, or another reversible problem may improve when the cause is corrected. Chronic autonomic disorders may require long-term management because the underlying problem cannot always be reversed.

Orthostatic hypotension is important because it is associated with falls, fainting, reduced quality of life, and higher rates of cardiovascular problems in some groups (2, 4). Treatment therefore focuses on maintaining safe mobility and daily function as well as improving symptoms.

The blood pressure number should always be interpreted in context. A low reading in a person who feels well is very different from a sudden fall in blood pressure accompanied by confusion, fainting, or signs of poor circulation.

Conclusion

Low blood pressure is not automatically harmful. Some people naturally have low readings without symptoms, while others develop dizziness, fainting, falls, or more serious problems when blood pressure falls. Common causes include dehydration, blood loss, medicines, heart disease, endocrine disorders, and problems with autonomic blood pressure control. Orthostatic hypotension is diagnosed by measuring the change in blood pressure after standing, while postprandial hypotension occurs after meals. Treatment focuses on the cause and on improving symptoms rather than simply raising the blood pressure number. Sudden severe hypotension with signs of poor organ blood flow requires urgent medical assessment.

References

1. McEvoy JW, McCarthy CP, Bruno RM, et al. 2024 ESC Guidelines for the management of elevated blood pressure and hypertension. Eur Heart J. 2024;45(38):3912-4018. https://doi.org/10.1093/eurheartj/ehae178


2. Wieling W, Kaufmann H, Claydon VE, et al. Diagnosis and treatment of orthostatic hypotension. Lancet Neurol. 2022;21(8):735-746. https://doi.org/10.1016/S1474-4422(22)00169-7


3. Huang L, Li S, Xie X, et al. Prevalence of postprandial hypotension in older adults: a systematic review and meta-analysis. Age Ageing. 2024;53(2):afae022. https://doi.org/10.1093/ageing/afae022


4. Moloney D, Youssef A, Okamoto LE. Management of Orthostatic Hypotension: A Review. JAMA Intern Med. 2026;186(6):744-753. https://doi.org/10.1001/jamainternmed.2026.0284


5. Schuurmans J, van Rossem BTB, Rellum SR, et al. Hypotension during intensive care stay and mortality and morbidity: a systematic review and meta-analysis. Intensive Care Med. 2024;50(4):516-525. https://doi.org/10.1007/s00134-023-07304-4


6. Kulkarni S, Jenkins D, Dhar A, Mir F. Treating Lows: Management of Orthostatic Hypotension. J Cardiovasc Pharmacol. 2024;84(3):303-315. https://doi.org/10.1097/FJC.0000000000001597

This article is part of the 'Public Education Series' initiative by Exon Publications.

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