High blood pressure, or hypertension, is often referred to as “the silent killer” because it typically progresses without obvious symptoms.
It is generally defined as a persistent reading of 140/90 mmHg or higher. Though targets vary by age and gender.
Understanding the underlying causes is the first step toward effective management and prevention.
Here are the 10 most common causes (or groups of) of hypertension.
This remains the most common diagnosis, accounting for 90% of cases worldwide.
It is not caused by a single disease but rather a combination of genetics, natural ageing, and cumulative lifestyle factors.
Over time, these elements cause the arteries to lose elasticity and the heart to work harder to circulate blood.
Obesity and diabetes act as a “double threat” to cardiovascular health.
Excess body fat increases the total volume of blood the heart must pump, while high blood sugar levels from diabetes damage the lining of the blood vessels.
Together, they lead to atherosclerosis and fluid retention, both of which drive up arterial pressure.
Daily habits play a critical role in blood pressure regulation. High sodium (salt) intake forces the body to hold onto extra water, increasing blood volume.
Smoking causes immediate arterial constriction and long-term damage, while excessive alcohol consumption can disrupt the nervous system’s control of blood vessels.
These are exacerbating factors primarily in primary/essential hypertension.
Physical abnormalities in the heart can mechanically elevate blood pressure. Coarctation of the aorta is a narrowing of the body’s main artery that forces the heart to pump against extreme resistance.
Similarly, aortic regurgitation—where blood leaks backward through the heart valve—requires the heart to pump a higher volume of blood with each beat to compensate.
In pregnancy the BP is usually low (under 110/70). But gestational (pregnancy-related) hypertension also occurs, and usually needs treatment.
135/85 can be high blood pressure in pregnancy – and 140/90 requires action
Preclampsia is a serious condition that typically occurs after 20 weeks of pregnancy.
It is characterised by high blood pressure and often signs of damage to other organ systems, most often the liver and kidneys.
It is believed to be caused by issues with the development of placental blood vessels, leading to systemic inflammation in the mother.
Many common medications can inadvertently raise blood pressure. Oral contraceptives and HRT (containing oestrogen) can cause blood vessel constriction in some users.
Corticosteroids (like prednisone) cause the body to retain salt and water. Additionally, NSAIDs (like ibuprofen) can interfere with the kidneys’ ability to regulate blood flow.
Healthy kidneys filter out waste and excess water, and regulate blood pressure via the renin-angiotensin-aldosterone (RAS) system.
When the kidneys are damaged by disease, they cannot properly manage fluid or hormones, leading to hypertension that often further accelerates CKD.
Most causes of CKD can cause hypertension, but it is important to exclude renovascular disease (RVD), also called Renal Artery Stenosis (RAS).
Sleep apnoea involves repeated pauses in breathing during sleep. Each time breathing stops, oxygen levels in the blood drop, triggering a “fight or flight” response.
This releases stress hormones like adrenaline that cause blood pressure to spike during the night and, eventually, remain elevated during the day. CPAP at night is usually required.
The adrenal glands produce hormones that control salt balance and stress responses. Conditions like Conn’s Syndrome (excess aldosterone) or Cushing’s Syndrome (excess cortisol) lead to massive salt and water retention.
Additionally, a Phaeochromocytoma (a very rare adrenal tumour) can release surges of adrenaline, causing sudden, life-threatening blood pressure spikes.
Both an overactive thyroid (hyperthyroidism) and an underactive thyroid (hypothyroidism) can impact blood pressure.
Hyperthyroidism makes the heart beat faster and harder, raising systolic pressure, while hypothyroidism can lead to stiffened arteries and increased diastolic pressure.
Other issues, such as parathyroid disease, can also disrupt calcium levels and arterial tone.
| Cause Category | Primary Impact | Key Examples |
| Systemic | Gradual aging/genetics | Essential Hypertension |
| Metabolic | Arterial damage/Inflammation | Obesity, Diabetes |
| Hormonal | Fluid retention/Vessel tone | Adrenal & Thyroid Disorders |
| Cardiac | Mechanical resistance | Aortic Regurgitaion, Coarctation |
| Gestational | Placental inflammation | Preeclampsia, Gestational Hypertension |
| Pharmacological | Chemical-induced salt retention | OCPs, HRT, Steroids, NSAIDs |
Medical Warning: A blood pressure reading above 180/120 mmHg is considered a hypertensive crisis. If this is accompanied by chest pain, shortness of breath, or numbness, seek emergency medical care immediately.
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