Low Blood Pressure: Symptoms, Causes and When It Actually Matters

Most of us have been trained to worry about blood pressure going up. Low blood pressure gets far less attention, which is why plenty of Australians spend years putting the dizzy spells down to standing up too fast, skipping breakfast, or simply being tired.

Sometimes that is exactly what it is. A naturally low reading with no symptoms is usually nothing to fix. But when the lightheadedness turns into near-fainting, or the fatigue stops lifting, it is worth understanding what is actually going on. If your symptoms are recurring, an online doctor consultation with an AHPRA-registered GP is a straightforward place to start, and you can do it from the couch instead of standing in a queue.

What is low blood pressure?

Blood pressure is the force your blood exerts against artery walls as your heart pumps. It is written as two numbers, for example 118/76 mmHg. The top number, systolic, is the pressure during a heartbeat. The bottom number, diastolic, is the pressure between beats.

Low blood pressure, known medically as hypotension, is when that force drops below the normal range. Here is the part most articles bury: a low number on its own is not a diagnosis. Some people, particularly younger adults and regular exercisers, simply run low and feel completely fine. Hypotension becomes a clinical issue when the pressure is low enough that your organs are not getting the blood flow they need, and symptoms start showing up.

What counts as a low blood pressure level?

As a general reference, a reading below 90/60 mmHg is usually considered low. The healthdirect guidance on low blood pressure and hypotension in Australia makes the same point about context: low blood pressure only matters when it has a negative effect on the body.

A few things worth knowing about readings:

• Either number can be low on its own. Systolic under 90 or diastolic under 60 can both count.
• Your blood pressure moves all day. It dips during sleep, after meals and in hot weather, and rises with stress and activity.
• A single low reading is not a pattern. Doctors generally look at several readings taken on different days.
• Context is everything. If you normally sit at 150/95 and you drop to 110/70, you may feel unwell even though 110/70 is a perfectly healthy number for someone else.

If you are checking at home, sit quietly for five minutes first, keep your arm supported at heart level, and record the time alongside the reading. A week of readings tells a doctor far more than one number quoted from memory.

Signs and symptoms of low blood pressure

The symptoms of low blood pressure come from the brain and other organs briefly not receiving enough blood. They often cluster around movement, heat and skipped meals.

Common day to day symptoms

• Dizziness or lightheadedness, especially when standing up
• Blurred or tunnelling vision, sometimes with grey or dark patches
• Fatigue that does not improve with rest
• Nausea
• Difficulty concentrating, or a woolly, unfocused feeling
• Cold, clammy or pale skin
• Rapid, shallow breathing or a noticeable heartbeat
• Feeling faint, or actually fainting

Many people describe the pattern rather than the symptom: fine while sitting, unsteady on standing, better again after a glass of water and a few minutes. That pattern is the useful detail to bring to a consultation.

Signs of low blood pressure that need urgent care

Call 000 or go to your nearest emergency department if low blood pressure comes with:

• Fainting, collapse, or inability to stay conscious
• Confusion, slurred speech, or unusual drowsiness
• Chest pain, or shortness of breath at rest
• A weak, racing pulse with cold and clammy skin
• Bleeding, severe vomiting or diarrhoea alongside the symptoms
• Symptoms following a fall, a head knock, or a suspected allergic reaction

These can signal shock, significant fluid loss or a cardiac problem. Telehealth is not the right channel for any of them.

What causes low blood pressure?

Low blood pressure causes fall into a few broad groups, and more than one can be in play at once.

Everyday and situational causes

• Dehydration, which is a common cause in an Australian summer or after a big training session
• Heat, hot showers and long periods standing still
• Skipping meals, or a sharp drop after a large meal, which is more common in older adults
• Alcohol, which widens blood vessels and drops pressure
• Prolonged bed rest or a sudden reduction in activity
• Pregnancy, where blood pressure often dips in the first and second trimesters

Medical causes worth investigating

• Heart conditions, including a very slow heart rate, valve problems or heart failure
• Thyroid and adrenal disorders, which affect the hormones regulating blood pressure
• Anaemia or blood loss, including slow internal blood loss that is easy to miss
• Diabetes, which over time can affect the nerves controlling blood pressure
• Severe infection, which can cause a dangerous drop and needs emergency care
• Nutritional deficiencies affecting red blood cell production

Medication-related causes

Quite a few commonly used medicines lower blood pressure, either as their purpose or as a side effect. This includes treatments for heart conditions, fluid retention, prostate symptoms, depression and Parkinson’s disease. Doses that suited you a year ago may not suit you now, particularly if your weight, kidney function or fluid intake has changed. Never stop or adjust a prescribed medicine on your own. Book a review instead, and if a change is agreed you can request a repeat or updated prescription online once the doctor has assessed what is appropriate.

Orthostatic hypotension: the head rush when you stand up

If your symptoms hit specifically in the few seconds after standing, this is likely orthostatic or postural hypotension. Normally your body tightens blood vessels and lifts your heart rate the moment you stand, to stop blood pooling in your legs. When that response is slow or blunted, pressure stays low and the symptoms follow. The Better Health Channel explanation of dizziness caused by orthostatic hypotension covers how the mechanism fails and why it becomes more common with age.

It is worth taking seriously for one practical reason: falls. In older adults, the fracture from a fall is usually a bigger problem than the blood pressure reading that caused it.

Low blood pressure treatment: what a doctor will look at first

Low blood pressure treatment is built around the cause, not the number. That is why assessment comes before anything else. A doctor will typically want to know when the symptoms happen, how long they last, what you were doing beforehand, your fluid and salt intake, and a full list of your current medicines and supplements.

Investigations often start with blood tests, since anaemia, thyroid problems, blood sugar issues and electrolyte imbalances are all common and all detectable. Your GP can issue a pathology referral for blood tests after a consultation, so you can visit a collection centre near you rather than waiting for an in-person appointment first.

Where the picture points to the heart, or where symptoms persist without a clear explanation, the next step may be a specialist referral to a cardiologist for further testing. Where a medication looks like the driver, the answer is usually a medication review rather than anything new.

Only an AHPRA-registered doctor can determine which of these applies to you. Any change to fluid intake, salt intake or prescribed medicines should come from that assessment, because advice that helps one cause can make another one worse.

Practical habits that tend to help

While the cause is being sorted out, these are the general measures most doctors discuss. They are low risk, but they are not a substitute for assessment.

• Drink water consistently through the day rather than in large bursts
• Stand up in stages: sit on the edge of the bed, wait, then rise
• Flex your calves and ankles before standing, and avoid standing still for long stretches
• Eat smaller meals more often if you feel worse after eating
• Go easy on alcohol, and take care with very hot showers, saunas and long periods in the sun
• Keep some activity going, since prolonged inactivity tends to make the response worse
• Ask your doctor before increasing salt or using compression stockings, as neither suits everyone

When to book a consultation about low blood pressure

A low reading with no symptoms generally needs nothing more than a mention at your next appointment. Book sooner if you are getting repeated dizziness or near-fainting, if fatigue is interfering with work, if symptoms started after a medication change, or if you have fainted even once.

A telehealth consultation works well here, because most of the assessment is history and pattern. Bring your home readings, a list of your medicines, and a rough note of when symptoms hit. If the episodes have already cost you time at work, you can request a medical certificate online after your consultation. Bulk billed GP consultations are available for eligible patients, so there is no reason to keep putting the conversation off.

Frequently Asked Questions