In most cases, it's not clear exactly what causes high blood pressure. But there are things that can increase your risk.
You might be more at risk if you:
- are overweight
- eat too much salt and do not eat enough fruit and vegetables
- do not do enough exercise
- drink too much alcohol or coffee (or other caffeine-based drinks)
- do not get much sleep or have disturbed sleep
- are over 65
- have a relative with high blood pressure
- are of black African or black Caribbean descent
- live in a deprived area
Making healthy lifestyle changes can sometimes help reduce your chances of getting high blood pressure and help lower your blood pressure if it's already high.
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
- long-term kidney infections
- obstructive sleep apnoea – 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 – such as an underactive thyroid, an overactive thyroid, Cushing's syndrome, acromegaly, increased levels of the hormone aldosterone (hyperaldosteronism), and phaeochromocytoma
- lupus – a condition in which the immune system attacks parts of the body, such as the skin, joints and organs
- scleroderma – 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
- 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 – such as venlafaxine
In these cases, your blood pressure may return to normal once you stop taking the medicine or drug.