Low blood pressure (hypotension)

Hypotension is when your blood pressure is much lower than normal. We explain the symptoms and causes of low blood pressure and provide tips for managing it.

Blood pressure is a measure of how hard your blood pushes against the walls of your arteries. 

A blood pressure reading consists of two numbers and is written as a figure like 120/80.  

The first number is a measure of how much pressure is in your arteries when your heart beats. It is called the systolic pressure.

The second number is a measure of the pressure in your arteries when your heart relaxes. This is the diastolic pressure.
 

What is low blood pressure (hypotension)?

For most people an ideal blood pressure is 120/80 or below. However, sometimes blood pressure can get too low. This is called low blood pressure, or hypotension.

Low blood pressure is when the top number (systolic pressure) is less than 90 mmHg, and the bottom number (diastolic pressure) is less than 60 mmHg.

Low blood pressure symptoms

Some people won’t have any symptoms of low blood pressure. 

For others, symptoms can include:

• blurred vision
• difficulty concentrating or confusion
• fainting or feeling like you’re going to faint 
• feeling dizzy, lightheaded, or unsteady
• feeling sick (nausea)
• feeling weak or very tired
• heart palpitations (your heartbeats feel different or more noticeable). 

Low blood pressure symptoms are more likely to occur:

• during exercise or other physical activities
• in the morning when blood pressure is naturally lower
• when standing up after lying or sitting down.

What causes low blood pressure?

There are several factors that can cause low blood pressure, including:

• alcohol (although alcohol usually increases blood pressure, sometimes it can lead to a sudden drop)
• dehydration due to vomiting or diarrhoea or caused by heat (for example in hot weather, exercising or overheating in hot water such as bath, sauna or spa pool)
• other medical conditions, such as diabetes, heart failure, Parkinson's disease, low heart rate (bradycardia), some hormone and thyroid conditions, problems with your blood vessels 
• medical emergencies, such as heart attack, severe allergic reaction (anaphylaxis), severe burns, extreme blood loss, severe infection (septic shock) or other causes of extreme pain
• some medications, including those for high blood pressure, Parkinson’s disease, depression, fluid retention, erectile dysfunction, pain and some over-the-counter medications
• some illegal drugs
• long periods in bed or sitting
• pregnancy, particularly in the first 24 weeks
• standing up, postural hypotension.
   

Postural hypotension (orthostatic hypotension)

Postural hypotension, or orthostatic hypotension, is a type of low blood pressure that happens when you change position.
 
When you’re sitting or lying down your blood pressure is normal, but once you stand up it drops suddenly, making you feel dizzy or light-headed. 

It can also happen if you stand still for too long. 

Postural hypotension is more common in older people, but it can occur at any age. It is caused by changes to our arteries as we age and can increase the risk of falls and injuries. 

If you’re taking medications for high blood pressure, talk to your doctor or nurse as your doses may need to be adjusted. 

When should I get help?

Having low blood pressure isn’t a serious problem for most people. And what’s considered low for one person, may be normal for someone else.

Most healthcare providers consider blood pressure to be too low only if it causes symptoms.

A one-off low reading isn’t usually a problem unless you’re experiencing other symptoms. You may like to keep a record of your blood pressures to take to your GP. 

More about home monitoring

If you are experiencing dizziness, nausea and light-headedness or other symptoms, or if your blood pressure is unusually low for you, talk to your doctor or Healthline for further advice. 
 

How is low blood pressure diagnosed?

Your healthcare professional will diagnose hypotension with a blood pressure check.

Your GP may also want you to have other tests, like an ECG or blood tests, to see if there are any other causes for your symptoms.

The doctor may ask you to monitor your blood pressure for a period of time and record the results.

Accurate home blood pressure monitoring

How is low blood pressure treated?

Lifestyle changes

Simple lifestyle changes can reduce low blood pressure symptoms. 

They can also reduce the risk of complications that happen as a result of low blood pressure.

There are a range of lifestyle changes you could consider. 

• Talk to your doctor about your current medications to see if some changes could help.
• Get up and down slowly when changing position. After lying down, sit up slowly on the edge of the bed or couch with your feet on the floor. Wait a short time before standing up.
• Drink more fluids, preferably water, (unless you have been told otherwise by a doctor).
• Your healthcare provider may recommend compression clothing to improve blood flow in your legs.
• Avoid hot baths, saunas and spa pools.

Medication for hypotension

If your symptoms are particularly troublesome, you may be prescribed medication for low blood pressure. Usually, you’ll need to be referred to a specialist for this. 

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