Low blood pressure

Blood pressure is the force of your blood pushing against the walls of your arteries. When this pressure is low, you can feel unsteady, dizzy or faint.

Key points

  • Blood pressure measures the amount of pressure as your heart beats (systolic) and when it relaxes between beats (diastolic).
  • Blood pressure is considered low when the measure for systolic over diastolic is under 90/60; this is known as hypotension.
  • Some people naturally have low blood pressure, especially if they are very fit, and this is not a problem.
  • For others, if your blood pressure gets too low, it starts to reduce blood flow to your organs, which is when you might feel unsteady, dizzy or faint.
  • Blood pressure naturally varies, getting higher throughout the day, and lower when it is hot or you have just eaten.
  • Even though blood pressure tends to rise with age, you are more likely to experience low blood pressure from getting up quickly (called postural or orthostatic hypotension) as you get older.

What causes low blood pressure?

  • Being dehydrated (needing to drink more water).
  • Being pregnant, donating blood, bleeding a lot.
  • An infection or allergic reaction.
  • Having drugs or alcohol in your system.
  • Having an underlying illness such as a heart condition, anaemia, or a hormonal or nervous system disorder.
  • Some types of medication, such as medication to reduce high blood pressure or treat Parkinson’s Disease, as well as diuretics (water tablets) and some antidepressants.

What are the symptoms of low blood pressure?

Symptoms include:

  • feeling dizzy, lightheaded or unsteady
  • fainting
  • blurred vision
  • heartbeats that are more noticeable (palpitations)
  • feeling sick (nausea), weak or very tired.

How is low blood pressure diagnosed?

See your doctor if you often have the symptoms listed above. They will measure your blood pressure and ask you questions about your medical history and lifestyle. They might refer you for blood tests or an electrocardiogram (ECG) to see if there are any underlying conditions causing the low blood pressure.

How is low blood pressure treated?        

If you have an underlying condition, this needs to be treated, or if your medication is lowering your blood pressure, your doctor will discuss options.

Sometimes, if your low blood pressure is causing you to fall a lot and you are at risk, your doctor may refer you to a specialist. They will assess whether you need a medication called fludrocortisone to raise your blood pressure.

Otherwise, follow the self-care guidelines below.

Self-care for low blood pressure

  • Don’t stand up quickly.
  • Drink plenty of water.
  • Ask your doctor whether you need more salt in your diet.
  • Discuss your medication options with your doctor.
  • If you feel faint, dizzy or unsteady, stop what you are doing and sit or lie down, and drink some water.

If you want to track your blood pressure yourself, talk to your doctor about getting a device to do so at home. You can track your readings over time using an app (see below).

Support with low blood pressure

Healthline for free advice from trained registered nurses. Freephone 0800 611 116
Online Hypotension Support Forum an American-based online health community featuring member and doctor discussions.

How is low blood pressure prevented?

Drink plenty of water and stay hydrated, stand up carefully and tell your doctor if you start to have symptoms of low blood pressure when you start or change your medication.

Learn more about low blood pressure

Low Blood Pressure NHS Choices, UK, 2015
Orthostatic Hypotension Better Health, Australia, 2011

References

Arnold AC, Shibao C. Current Concepts in Orthostatic Hypotension Management C. Curr Hypertens Rep (2013) 15: 304
Out-of-clinic blood pressure testing in primary care BPAC, NZ, 2016