Low blood pressure (hypotension)

What is low blood pressure?

Low blood pressure (hypotension) is when your blood pressure is equal to or lower than 90/60 mm Hg — the normal range is 120/80 mm Hg. 

• The higher number (90) represents systolic pressure — how much pressure your blood exerts against your artery walls when your heart beats
• The lower number (60) represents diastolic pressure — how much pressure your blood exerts against your artery walls while your heart is resting between beats

Low blood pressure isn’t usually a cause for concern, and you might not notice any symptoms or be aware that you have it. But if it's lower than normal or drops suddenly, your heart, brain, and other organs might not get enough blood. As a result, they might not function as well as they should, which can cause a variety of associated signs of low blood pressure.

What causes low blood pressure?

You might naturally have low blood pressure — there might not be any specific reason, or it might run in your family. In both cases, you might not experience any noticeable or troublesome signs of low blood pressure. Ageing can also cause a reduction in blood pressure levels in some people. 

There are many other possible causes of low blood pressure, including:

• medical conditions — like heart failure, abnormal heart rhythm (arrhythmias), conditions affecting your nervous system, hormonal imbalances, anaemia, diabetes, severe allergic reactions, and infections
• pregnancy — as your blood vessels expand to allow blood to flow to your uterus 
• dehydration — as your blood volume decreases
• blood loss — following severe injuries
• standing up too quickly (orthostatic hypotension) 
• after eating (postprandial hypotension) — blood travels to your abdominal organs during digestion, which doesn’t allow enough blood to return to your brain
• some medications — painkillers like aspirin, antidepressants, and medication used to treat heart disease

Low blood pressure symptoms

If your blood pressure is low, your brain and organs might not be receiving enough blood. As a result, common signs of low blood pressure include:

• feeling dizzy and tired
• nausea (feeling sick)
• confusion and unsteadiness
• blurred vision
• heart palpitations — you might feel like your heart is fluttering or pounding in your chest
• fainting

If you have orthostatic or postprandial hypotension, these symptoms can specifically occur when you suddenly stand up or a few hours after eating respectively. In some cases, like extreme blood loss or severe allergic reactions (anaphylaxis), your blood pressure might drop so low that your whole body goes into shock. This is an example of when low blood pressure is an emergency condition, as not enough oxygen circulates in your body. This might lead to organ damage.

Low blood pressure symptoms can be unpleasant and vary in intensity. It’s important to speak to your doctor about them to rule out any serious underlying health problems — even if they only occur occasionally.

How to find out if your blood pressure is too low

Measuring your blood pressure can tell you if you have low blood pressure. You can do this through your GP, or you can buy a blood pressure monitor to check your blood pressure at home.

While low blood pressure is rarely an emergency, it’s good practice to have your blood pressure checked routinely. Especially if you experience any symptoms or you’ve been diagnosed with hypotension.

A tilt table test can also see how your blood pressure varies upon changing position, from lying to standing specifically. To find out more about what’s causing your low blood pressure, your GP might also recommend blood tests and an electrocardiogram (ECG) — a test that’s used to check your heart’s rhythm and electrical activity. 

Low blood pressure treatment options

Your treatment plan for low blood pressure depends on what’s causing it. If hypotension is a side effect of the medications you’re taking, your GP might decide to adjust doses or try alternative therapies. Or if it’s a heart, hormonal, or neurological condition, you might be given a specific treatment that will also improve your low blood pressure.

If the cause isn’t clear, the main goal is to raise your blood pressure to reduce the symptoms you’re experiencing. 

There are many lifestyle changes you can try to help to improve the symptoms of low blood pressure, including:

• stand up slowly, from sitting, and when getting out of bed — carefully proceed from a lying position to sitting and then to standing
• avoid suddenly bending down or changing your head posture 
• don’t sit or stand for long periods of time
• raise the head of your bed or use extra pillows under your head —increases blood flow  and helps you stand up more easily
• eat small and frequent meals (especially if you have postprandial hypotension) — lying down or sitting for some time after eating might also help
• wear supportive compression socks — their elasticity helps circulation in your legs and increase blood pressure
• drink more water — aim for 2 litres a day to prevent dehydration
• don’t consume caffeinated drinks close to bedtime
• limit your alcohol consumption

Having naturally low blood pressure doesn’t cause any problems in most people and might actually seem desirable. But if your blood pressure is abnormally low, it’s common to experience unpleasant symptoms. While these aren’t often life-threatening and can be reduced with some lifestyle changes, it’s important to understand when low blood pressure is an emergency or a sign of a more serious underlying health condition. Always speak to your GP if you’re concerned about your hypotensive symptoms.

Want to know more about heart health? Find out about the causes, symptoms, and treatment of high blood pressure (hypertension).