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Causes - High blood pressure (hypertension)

High blood pressure (hypertension) rarely has noticeable symptoms. But if untreated, it increases your risk of serious problems such as heart attacks and strokes.

In most cases, it's not clear exactly what causes high blood pressure. But there are several things that can increase your risk.

Who's at risk of high blood pressure

Factors that can raise your risk of developing high blood pressure include:

  • age – the risk of developing high blood pressure increases as you get older
  • a family history of high blood pressure
  • a high amount of salt in your food
  • lack of exercise
  • being overweight
  • regularly drinking large amounts of alcohol
  • smoking
  • long-term sleep deprivation
  • obstructive sleep apnoea - very heavy snoring can be a sign of this

Making healthy lifestyle changes can help keep your blood pressure at a normal level.

Find out more about how to prevent high blood pressure

Known causes of high blood pressure

In about 1 in 20 cases, high blood pressure happens as the result of an underlying health condition or taking a certain medicine.

Health conditions that can cause high blood pressure include:

  • kidney disease
  • diabetes
  • long-term kidney infections
  • obstructive sleep apnoea - this where the walls of the throat relax and narrow during sleep, interrupting normal breathing
  • glomerulonephritis – damage to the tiny filters inside the kidneys
  • narrowing of the arteries supplying the kidneys
  • hormone problems - these could be an underactive thyroid, an overactive thyroid, Cushing's syndrome, or acromegaly
  • lupus – a condition in which the immune system attacks parts of the body, such as the skin, joints and organs
  • scleroderma - this is a condition that causes thickened skin, and sometimes problems with organs and blood vessels

Medicines that can increase your blood pressure include:

  • the contraceptive pill
  • steroids
  • non-steroidal anti-inflammatory drugs (NSAIDs) – such as ibuprofen and naproxen
  • some pharmacy cough and cold remedies
  • some herbal remedies – particularly those containing liquorice
  • some recreational drugs – such as cocaine and amphetamines
  • some selective serotonin-noradrenaline reuptake inhibitor (SSNRI) antidepressants

In these cases, your blood pressure may return to normal once you stop taking the medicine or drug.

Page last reviewed: 3 January 2022
Next review due: 3 January 2025

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.