When you arise from a sitting to a standing position, ______ is altered to maintain blood pressure.

• Hypotension, or low blood pressure, means that the pressure of blood circulating around the body is lower than normal or lower than expected.
• Low blood pressure is only a problem if it has a negative impact on the body and produces symptoms.
• Some causes of hypotension include blood loss, dehydration and certain medications, such as antihypertensive drugs.

The heart pumps blood around the body through the blood vessels. Blood pressure is the amount of force exerted on the artery walls by the pumping blood. Blood pressure varies according to environmental demands. For example, it rises during physical exertion and drops in extreme heat.

Hypotension, or low blood pressure, means that the pressure of blood circulating around the body is lower than normal, or lower than expected given the environmental conditions. However, ‘hypotension’ is a relative term – one person may have low blood pressure compared to others of similar physical characteristics, but may be perfectly healthy.

Low blood pressure is only a problem if it has a negative impact on the body. For example, vital organs (particularly the brain) may be starved of oxygen and nutrients if the blood pressure is too low for that particular person.

Symptoms of hypotension

Substantial blood loss can cause a sudden drop in blood pressure (shock). The most dramatic symptom of sudden hypotension is unconsciousness. Usually, low blood pressure develops over time.

Symptoms include:

• Light-headedness, when standing from a sitting or lying position
• Unsteadiness
• Dizziness
• Weakness
• Blurred vision
• Fatigue
• Fainting.

Causes of hypotension

Blood pressure is measured using a device known as a sphygmomanometer. If the measurement drops 30mmHg below the person’s usual blood pressure, this is considered to be hypotension.

Low blood pressure has many different causes including:

• Emotional stress, fear, insecurity or pain (the most common causes of fainting)
• Dehydration, which reduces blood volume
• The body’s reaction to heat, which is to shunt blood into the vessels of the skin, leading to dehydration
• Blood donation
• Internal bleeding, such as a perforated stomach ulcer
• Blood loss from trauma, such as a road accident or deep cut
• Pregnancy
• Medications for high blood pressure
• Diuretics, which produce fluid loss
• Medications for depression
• Medications for certain heart conditions
• Allergic reaction to certain drugs or chemicals
• Some forms of infection, such as toxic shock syndrome
• Heart disease, which can hamper the pumping action of the heart muscle
• Some nervous system disorders, such as Parkinson’s disease
• Addison’s disease (where the adrenal glands fail to produce sufficient blood-pressure-maintaining hormones).

Orthostatic hypotension

Generally, when you stand upright from a sitting or lying position, the blood vessels in your body respond to gravity by constricting. This increases blood pressure. Orthostatic hypotension means that the blood vessels don’t adjust to a standing position and, instead, allow the blood pressure to drop, resulting in a feeling of light-headedness.

Causes include:

• Nervous system diseases, such as neuropathy
• Prolonged bed rest
• Dehydration
• Irregular heart beat (heart arrhythmia).

Treatment for hypotension

Treatment depends on the cause. For example, the dosages of existing medications may need to be altered or a bleeding stomach ulcer surgically repaired. If no particular cause can be found, drugs may be used to raise blood pressure. In extreme cases, a lower body pressure suit may be required.

Where to get help

Things to remember

• Hypotension, or low blood pressure, means that the pressure of blood circulating around the body is lower than normal or lower than expected.
• Low blood pressure is only a problem if it has a negative impact on the body and produces symptoms.
• Some causes of hypotension include blood loss, dehydration and certain medications, such as antihypertensive drugs.

This page has been produced in consultation with and approved by:

• Orthostatic hypotension is a form of low blood pressure caused by blood vessels failing to constrict when the body takes an upright position.
• It is usually a symptom of an underlying disorder rather than a disease in itself.
• The incidence of orthostatic hypotension increases with age.

When we stand up from sitting or lying down, our blood vessels respond to gravity by narrowing to prevent our blood pressure falling. This ensures a steady supply of oxygenated blood to the brain. Orthostatic hypotension is a form of low blood pressure. It happens when the blood vessels do not constrict (tighten) as you stand up. It is usually a symptom of an underlying disorder rather than a disease in itself. The condition is also known as postural hypotension.Everyone is likely to experience a mild form of postural hypotension at some time. It’s the lightheaded feeling you may get if you leap out of bed very quickly.

Symptoms of orthostatic hypotension

• Blurry vision
• Dizziness
• Light-headedness
• Mental confusion
• Nausea
• Muscle tremors
• Fainting.

Blood pooling explained

Causes of orthostatic hypotension

• Fever
• Prolonged bed rest
• Excessive amounts of alcohol
• Some medications, such as some diuretics or antihypertensive (high blood pressure) medications
• Dehydration due to vomiting, diarrhoea or both, as in gastroenteritis
• Certain conditions, such as anaemia, diabetes, varicose veins or adrenal insufficiency
• Nervous system disease, such as Parkinson’s disease or neuropathy
• Heart problems, including irregular heart beat (heart arrhythmia), congestive heart failure, aortic stenosis or heart attack
• Spinal cord conditions such as syringomyelia
• Shy Drager syndrome, a degenerative disorder of the brain and spinal cord that affects functioning of the autonomic nervous system
• Significant blood loss.

Other causes of dizziness

Old age is an important risk factor

• Digestion – when you eat and then digest food, an increased blood supply is sent to your intestines. Orthostatic hypotension is more likely to occur about 15 to 45 minutes after eating a meal (this is known as post-prandial hypotension).
• Standing – if you stand up for a long time, it causes a slow but steady drop in blood pressure.
• Frailty and chronic sickness – these are more common in old age.

Diagnosis of orthostatic hypotension

• Medical history, including medical conditions and drugs taken on a regular basis
• Physical examination
• Measuring blood pressure when lying down versus standing up
• Blood tests to check, for example, blood sugars or adrenal hormones
• Echocardiography, an imaging scan of the heart, to check for certain heart conditions
• Other tests, depending on individual factors.

Treatment of orthostatic hypotension

• Fluids to treat dehydration
• Management of diabetes, such as regular insulin injections
• Changes in medication or altered doses if drugs are the cause (sometimes, however, stopping or altering the dose of a particular medication may cause more harm than good and must be carefully considered in consultation with your doctor)
• Medication, surgery or both to treat heart conditions
• Medication to increase blood volume or pressure, including corticosteroids
• Medications to treat orthostatic hypotension including pyridostigmine, a drug used in the treatment of myasthenia gravis
• A range of treatments, since orthostatic hypotension may have two or more causes
• In some cases, a lower body pressure suit is required.

Self-help suggestions

• Prop your head up with pillows when you’re in bed to reduce the likelihood of orthostatic hypotension when you get up.
• Get up slowly from a sitting or lying position to allow your blood vessels time to adjust.
• Wear support stockings to reduce the pooling of blood in the legs, which helps to boost blood pressure throughout the body.
• Eat small, frequent meals instead of three large meals per day.
• Drink plenty of fluids throughout the day to prevent dehydration.
• Limit alcohol consumption. Alcohol can cause dehydration and dilation of blood vessels.
• Consider drinking small but regular doses of caffeine, which boost blood pressure. A cup of coffee or tea with each meal tends to reduce the severity of orthostatic hypotension. Remember, however, that caffeinated drinks can cause dehydration, so moderation is the key.
• Try other drinks that contain caffeine, like hot chocolate or cola, if you don’t like coffee or tea.
• Avoid vigorous exercise, hot baths, saunas and any hot environment because heat causes blood vessels to widen (dilate).
• Avoid standing without moving for long periods of time.
• Avoid ascending quickly to high altitudes.
• See your doctor for regular blood pressure check-ups.

Where to get help

• Your doctor
• NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice 24 hours, 7 days a week.

Things to remember

• Orthostatic hypotension is a form of low blood pressure caused by blood vessels failing to constrict when the body takes an upright position.
• It is usually a symptom of an underlying disorder rather than a disease in itself.
• The incidence of orthostatic hypotension increases with age.

• Shy Drager Syndrome (Multiple Syndrome Atrophy), Brain Australia. More information here.
• ‘Orthostatic hypotension’, 2003, American Family Physician, vol. 68, no. 12. More information here.
• New orthostatic hypotension treatment reduces symptoms without causing high blood pressure, News-Medical.Net. More information here.
• ‘Pyridostigmine treatment trial in neurogenic orthostatic hypotension’, 2006, Archives of Neurology, vol. 63, no. 4. More information here.

This page has been produced in consultation with and approved by: