What Causes High Blood Pressure? Understanding Your Risk Factors

If you have recently used our Blood Pressure Chart to plot your readings, you might have noticed that your numbers fluctuate. But when those numbers consistently stay high, it is known as hypertension.

For over 90% of people with high blood pressure, there isn't one single clear cause. Instead, it is usually a combination of lifestyle factors, genetics, and age. This is what doctors call "primary hypertension." However, understanding what causes high blood pressure is the first step towards taking control of it.

Here is a breakdown of the most common causes and risk factors for high blood pressure.

1. Lifestyle Choices

Your daily habits have a direct impact on your heart health. The following are the most common lifestyle contributors to hypertension:

Too much salt: Salt forces your body to hold onto water, which puts extra fluid into your blood and increases pressure. In the UK, we often eat far more than the recommended 6g a day, mostly from processed foods.

Lack of exercise: A sedentary lifestyle means your heart has to work harder to pump blood.

Being overweight: Carrying extra weight requires more blood to supply oxygen and nutrients to your tissues, increasing the pressure on your vessel walls.

Alcohol and Smoking: Regularly drinking above the recommended 14 units a week raises blood pressure over time, while smoking causes immediate, temporary spikes and long-term vessel damage.

2. Age and Genetics

Some factors are unfortunately out of our control, but knowing them helps you stay vigilant.

Age: As you get older, the risk of high blood pressure increases because your blood vessels naturally lose some of their stretchiness and elasticity.

Family History: If your parents or siblings have high blood pressure, your risk is significantly higher.

Ethnicity: In the UK, people of Black African or Black Caribbean descent are more likely to develop high blood pressure, and often at a younger age.

3. Secondary Hypertension (Underlying Health Conditions)

For about 10% of people, high blood pressure is caused by a specific underlying condition. This is called "secondary hypertension." Common causes include:

Kidney disease: The kidneys play a vital role in regulating blood pressure; if they aren't working properly, pressure can rise.

Diabetes: High blood sugar can damage blood vessels, making them stiff and leading to hypertension.

Sleep Apnoea: This condition, where breathing stops and starts during sleep, causes drops in oxygen levels that strain the cardiovascular system.

4. What Causes a Sudden Increase in Blood Pressure?

Sometimes, you might see a "spike" on your blood pressure chart that doesn't match your usual trend. This can be caused by:

Stress or Anxiety: White Coat Syndrome (fear of doctors) or general stress can cause temporary spikes.

Caffeine: A strong coffee right before a reading can skew the results.

Certain Medications: Some antidepressants, decongestants, and the contraceptive pill can raise blood pressure.

Summary: Knowledge is Power

You cannot change your genetics or your age, but you can control your lifestyle.

Because high blood pressure rarely has symptoms, the only way to know if these causes are affecting you is to check your numbers regularly. By using a home blood pressure monitor and plotting your results on our Blood Pressure Chart, you can spot trends early and share them with your GP.